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According to the latest news, a new type of copper alloy material has been successfully developed in China recently. This material not only has excellent mechanical properties and corrosion resistance, but also has good plasticity and welding performance. It is known as the "dark horse" in the field of copper alloys. It is reported that this new type of copper alloy material is made of a variety of metal elements through special melting process. It has been verified by experiments that the strength and hardness of this material are much higher than that of traditional copper alloys, and it also has better corrosion resistance and can be used in harsh environments for a long time. The research and development team of the copper alloy material said that this material can not only be widely used in ships, automobiles, aerospace and other fields, but also can be used to manufacture high-end home appliances and electronic products. At present, the material has begun to be tested in some fields and has achieved good results. According to industry insiders, copper alloy, as an important engineering material, has always been widely concerned. The advent of this new type of copper alloy material will further expand the application field of copper alloy and provide new impetus for the development of related industries. It is understood that the R&D team is still exploring new application fields of copper alloy materials, and plans to further improve its performance and quality, so as to make greater contributions to the development of Chinese manufacturing.

According to the latest report, the application of high-resistance electric heating alloys in the field of electric heating is more and more extensive. High-resistance electric heating alloy is a special alloy material with high resistivity and high temperature coefficient, which can work stably in high temperature environment, so it is widely used in electric heaters, electric furnaces, water heaters and other fields. It is understood that the main components of high-resistance electric heating alloys are nickel, chromium, iron and other metal elements, of which nickel is the most important component. The resistivity of high-resistance electrothermal alloys is dozens or even hundreds of times that of ordinary metals, so they have been widely used in the field of electrothermal. At present, high-resistance electric heating alloy has become one of the important materials in the field of electric heating, and its application range covers electric heaters, electric furnaces, water heaters and other fields. In the field of electric heaters, high-resistance electric heating alloys can be used to manufacture electric heating wires, electric heating tubes and other components. In the field of electric furnaces, high-resistance electrothermal alloys can be used to manufacture heating elements, furnace cores and other components. In the field of water heaters, high-resistance electrothermal alloys can be used to manufacture elements such as heating pipes. The application of high-resistance electric heating alloy not only improves the performance of electric heating products, but also improves the safety of electric heating products. The high-resistance electric heating alloy can work stably in a high temperature environment and is not easy to burn out, thereby reducing the failure rate of electric heating products. At the same time, the use of high-resistance electrothermal alloys can also improve the energy-saving performance of electrothermal products and reduce electricity bills. To sum up, high-resistance electric heating alloys have broad application prospects and will play an increasingly important role in the field of electric heating. In the future, the development and application of high-resistance electrothermal alloys will be further deepened, bringing more opportunities and challenges to the development of the electrothermal field.

It is reported that a new type of welding wire has recently received widespread attention in the market. This welding wire adopts advanced technology, which has higher welding efficiency and better welding quality. According to the welding wire manufacturer, the welding wire uses a new type of welding material, which can be welded at a lower temperature, thereby reducing energy consumption during the welding process. At the same time, the welding wire also has better oxidation resistance and corrosion resistance, and can be welded in more harsh environments. The welding wire has a wide range of applications and can be used for welding in steel structures, ships, automobiles, machinery, electric power and other fields. At the same time, the welding wire can also be used to weld the interface between different materials, such as steel-aluminum, copper-aluminum, etc. It is reported that the welding wire has passed a number of international certifications, such as CE certification, ISO9001 quality management system certification and so on. The introduction of this welding wire will have a positive impact on the welding industry, improve welding efficiency and quality, and provide better support for the development of all walks of life.

Recently, Inconel Bars And Rods has become a hot topic in aviation, aerospace, petrochemical, energy and other fields. Inconel Bars And Rods is a superalloy that offers extremely high corrosion resistance, high temperature strength, and excellent mechanical properties for long-term service in extreme environments. Inconel Bars And Rods have a wide range of applications, and can be used to manufacture high-temperature, high-pressure, and highly corrosive equipment and components such as aero engines, gas turbines, nuclear reactors, chemical reactors, and oil drilling rigs. Inconel Bars And Rods can also manufacture high-temperature alloy steel wire, high-temperature alloy electrode, high-temperature alloy plate and other materials, which are widely used in aviation, aerospace, petrochemical, energy and other fields. The advantages of Inconel Bars And Rods are not only its high strength, high corrosion resistance and high temperature performance, but also its good machinability, good weldability and good heat treatability. The production process of Inconel Bars And Rods is also very mature, and high-quality Inconel Bars And Rods can be produced by forging, hot rolling, cold drawing, etc. At present, many companies at home and abroad are actively developing and producing Inconel Bars And Rods, including Inconel in the United States, Aubert & Duval in France, VDM Metals in Germany, and Nippon Bars and Rods in Japan. These enterprises have continuously improved the quality and performance of Inconel Bars And Rods, providing high-quality material support for high temperature, high pressure, strong corrosive equipment and components in various fields. In short, the application prospect of Inconel Bars And Rods is very broad, and it will play an increasingly important role in the fields of aviation, aerospace, petrochemical, energy and other fields in the future.

2.4611 high-temperature alloy is a high-temperature alloy of 760℃800MPa grade high-temperature material. Casting high-temperature alloy refers to a type of high-temperature alloy that can or can only be formed by casting methods. Its main features are: 1. It has a wider range of composition. Since it is not necessary to take into account its deformation processing performance, the design of the alloy can focus on optimizing its use performance. For example, for nickel-based superalloys, the content of γ'can be adjusted to 60% or higher by adjusting the composition, so that the alloy can still maintain excellent performance at a temperature as high as 85% of the melting point of the alloy. 2. It has a broader application field. Due to the special advantages of the casting method, it is possible to design and manufacture near-net shape or no margin high-temperature alloy castings with arbitrary complex structures and shapes according to the use needs of the parts. According to the service temperature of the casting alloy, it can be divided into the following three categories: Type 1: Equiaxed crystal casting superalloys used at -253~650℃. These alloys have good comprehensive properties in a wide range of temperatures, and they can maintain strength and plasticity at low temperatures without decreasing. For example, the Monel K500 alloy, which is used in aerospace and aerospace engines, has a tensile strength of 1000 MPa, a yield strength of 850 MPa, and a tensile plasticity of 15% at 650°C; its endurance life under stress at 650°C and 620 MPa is 200 hours. It has been used in the manufacture of diffuser casings in aero-engines and various complex structural parts for pumps in aerospace engines. Type 2: Equiaxed crystal casting superalloys used at 650~950℃. These alloys have higher mechanical properties and thermal corrosion resistance at high temperatures. For example, K419 alloy, at 950°C, the tensile strength is greater than 700MPa, and the tensile ductility is greater than 6%; at 950°C, the endurance strength limit for 200 hours is greater than 230MPa. This type of alloy is suitable for use as aero-engine turbine blades, guide vanes and cast turbines. Type 3: Directionally solidified columnar crystals and single crystal superalloys used at 950~1100℃ have excellent comprehensive performance and thermal corrosion resistance in this temperature range. For example, DD402 single crystal alloy has a durability life of more than 100 hours under a stress of 1100°C and 130MPa. This is a turbine blade material of domestic use temperature, which is suitable for making the first-stage turbine blade of a new high-performance engine. With the continuous improvement of precision casting technology, new special processes are also emerging. Fine-grain casting technology, directional solidification technology, CA technology of complex thin-walled structural parts, etc. have greatly improved the level of casting high-temperature alloys, and the scope of application has continued to increase.

1. Different definitions Nickel-based alloy is a special kind of stainless steel, a kind of high-alloy stainless steel containing high nickel, high chromium and high molybdenum. Stainless steel is the abbreviation of stainless and acid-resistant steel. Steels that are resistant to weak corrosive media such as air, steam, and water or have rust resistance are called stainless steels. 2. High performance Nickel-based alloys have very good local corrosion resistance. They have good pitting corrosion resistance and good stress corrosion resistance under seawater, air-filled, crevices, and low-speed erosion conditions. It is a substitute for Ni-based alloys and titanium alloys. Material. At the same time, it has better high temperature or corrosion resistance. And stainless steel is almost in this respect. 3. Different classification The phase structure of nickel-based alloys is a stable austenitic metallurgical structure. Stainless steel is often divided into martensitic steel, ferritic steel, austenitic steel, austenitic-ferritic (duplex) stainless steel and precipitation hardening stainless steel according to the state of organization. Extended information Precision alloys, including nickel-based soft magnetic alloys, nickel-based precision resistance alloys, and nickel-based electric heating alloys. The most commonly used soft magnetic alloy is Permalloy with about 80% nickel. Its maximum permeability and initial permeability are high, and its coercivity is low. It is an important core material in the electronics industry. The main alloying elements of nickel-based precision resistance alloys are chromium, aluminum, and copper. This alloy has high resistivity, low temperature coefficient of resistivity and good corrosion resistance, and is used to make resistors. Nickel-based electric heating alloy is a nickel alloy with 20% chromium, which has good oxidation resistance and corrosion resistance, and can be used for a long time at a temperature of 1000 to 1100 ℃.

Quenching of forged gears is the main link that causes distortion. The basic method to control quenching distortion is to cool all parts of the gear as uniformly as possible. In addition, there are some noteworthy issues: 1. The influence of the hardenability of the steel itself on distortion. The higher the hardenability of the steel, the larger the volume involved in the transformation of the structure. When the workpiece is fully hardened and the whole is martensite, the volume difference between before and after quenching reaches the maximum, and the volume change of the steel with 1% carbon content is about 1%; if only half of the hardened, that is, half of the volume is quenched into martensite , The volume difference before and after quenching will be twice as small as the former. Therefore, the smaller the hardenability, the smaller the quenching distortion. On the contrary, the quenching distortion of the forged gear is greater. In many forged gears, in order to solve the distortion problem, the method of reducing the hardness of the core is often adopted. However, considering the strength of the gear, the hardness of the core cannot be too low, because an important reason for the fatigue failure of many gears is the deviation of the core hardness. Therefore, this has become a major contradiction in gear production. In order to solve the contradiction between gear strength and heat treatment distortion on the hardness requirements of the gear core, the hardenability of steel must be reasonably limited. Experiments show that as long as the hardenability (or core hardness) of the steel is similar, the distortion is also similar, which provides favorable conditions for controlling the distortion. For gear quenching distortion, the level of hardenability of steel is important, but more important is the bandwidth of steel hardenability, that is, the degree of fluctuation of hardenability. It is precisely because the hardenability of steel is of great significance to the quenching distortion of gears, all countries have included hardenability into steel standards. In recent years, the width of hardenable bands has been further narrowed. For example, the German "Technical Conditions for Delivery of Carburized and Hardened Steels" newly stipulated narrow hardenable steels, and the bandwidth has been reduced from 8 HRC of ordinary hardenable steels to 5 HRC. The new standard issued by our country in 2004 also reduced the width of the hardenable band compared with the original standard. 2. Forced pressure quenching. Many domestic forged gear manufacturers advocate free quenching in concept, in order to simplify the process, facilitate operation, and reduce costs. The development of pressure forced quenching technology and equipment has also been greatly affected. Unfortunately, it is difficult to control the distortion of gears with special structures like bevel gears by free quenching. For decades, the distortion of bevel gears has plagued my country's forging gear industry. In fact, in heat treatment production, for the bending distortion of workpieces such as small twist drills and slender rods, everyone recognizes the use of pressure straightening to achieve stable mass production; and for the thin-walled and large-walled gear manufacturing in forged gears. For parts such as disc bevel gears and auto synchronizer gear sleeves, the use of press quenching can also eliminate or reduce the influence of various potential distortion factors existing in the production process and heat treatment process under strong pressure. The price paid for free quenching is much lower. Therefore, press forced quenching should be an important and indispensable process. Recently, a moulded induction hardening process has been developed abroad for the hardening of special gears, especially bevel gears and synchronizer gear sleeves, and has achieved significant results. This new process combines the advantages of induction hardening and compression hardening, which can greatly reduce distortion, and can reduce or eliminate subsequent processes. Moreover, since induction hardening is quenched with water-based coolant, the gear after heat treatment does not need to be cleaned. At the same time, the built-in inductor can not only be used for heating and quenching, but also for heating and tempering parts without additional equipment, so the production cost is greatly reduced. We provide Nickel Alloys & Special Alloys High Precision Forgings, Top 10 Manufacture Specializing In Aerospace Forgings in China. Our advantages: ● 25 years experience in high-temperature alloy manufacturer. ● Professional technical team. ● 8 tons VIM +X tons VAR. ● Top 10 aerospace forgings manufacturer. ● Forged engine components supplier of Rolls-Royce.

What is die forging? Die forging refers to a forging method that uses a mold to form a blank on a dedicated die forging equipment to obtain a forging. The forgings produced by this method have precise dimensions, small machining allowances, complex structures and high productivity. What are the classifications of die forging? Die forging is divided into open die forging and closed die forging. The metal blank is compressed and deformed in a forging die cavity with a certain shape to obtain forgings. Die forging is generally used to produce parts with low weight and large batches. Die forging can be divided into hot die forging, warm forging and cold forging. Warm forging and cold forging are the future development direction of die forging, and also represent the level of forging technology. According to materials, die forging can be divided into ferrous metal die forging, non-ferrous metal die forging and powder product forming. As the name suggests, the materials are carbon steel and other ferrous metals, copper and aluminum and other non-ferrous metals and powder metallurgy materials. Extrusion should belong to die forging, which can be divided into heavy metal extrusion and light metal extrusion. Closed die forging and closed upsetting are two advanced processes of die forging. Because there is no flash, the utilization rate of materials is high. It is possible to complete the finishing of complex forgings with one process or several processes. Because there is no flash, the force-bearing area of the forging is reduced, and the required load is also reduced. However, it should be noted that the blanks cannot be completely restricted. For this reason, the volume of the blanks should be strictly controlled, the relative position of the forging dies and the measurement of the forgings should be controlled, and efforts should be made to reduce the wear of the forging dies.

What is the difference between nickel-based alloy materials and stainless steel? 1. Different definitions Nickel-based alloy is a special stainless steel, a high-alloy steel containing high nickel, high chromium, and high molybdenum. Stainless steel is the abbreviation for stainless steel and acid-resistant steel. Steel that is resistant to weakly corrosive media (such as air, steam, and water) or has anti-rust properties is called stainless steel. 2. High performance Nickel-based alloys have good local corrosion resistance. They have good pitting corrosion resistance and stress corrosion resistance under conditions of seawater, aeration, cracks and low-speed erosion. It is a substitute for nickel-based alloys and titanium alloys. At the same time, it has better high temperature resistance or corrosion resistance. In this regard, stainless steel is almost the best. 3. Different categories The phase structure of nickel-based alloys is a stable austenitic metallurgical structure. According to the state of organization, stainless steel is usually divided into martensitic steel, ferritic steel, austenitic steel, austenitic-ferritic (duplex) stainless steel and precipitation hardening stainless steel. Extended Information Precision alloys, including nickel-based soft magnetic alloys, nickel-based precision resistance alloys, and nickel-based electric heating alloys. The most commonly used soft magnetic alloy is Permalloy with a nickel content of approximately 80%. Its maximum permeability and initial permeability are high, and its coercivity is low. It is an important core material in the electronics industry. The main alloying elements of nickel-based precision resistance alloys are chromium, aluminum and copper. The alloy has high resistivity, low temperature coefficient of resistivity, and good corrosion resistance, and is used to manufacture resistors. Nickel-based electric heating alloy is a nickel alloy with a chromium content of 20%. It has good oxidation resistance and corrosion resistance and can be used for a long time at a temperature of 1000 to 1100 ℃.

Drainage system plays an important role in food safety when it comes to food production, processing and storage. Firstly, drainage is an integral part of the food processing and storage environment. Since drainage facilities, such as drainage floor drains or drainage channels keep open in the indoor environment, even though water traps or pipe traps are installed before the subsequent pipes are connected to block the odor in the pipes, can the accommodation capacity for the dirty material in the open space before blocking be ignored? What about the microbial bacteria or virus that can`t be seen in naked eyes? We have to profess that it is a serious issue neglected by people. As a matter of fact, the impact on the whole clean area that drainage system can have is not totally neglected. In early years, many academia or official organizations in Europe have already questioned the issue and standards for this field have been established for a while, such as: -Chartered institute of environmental health (CIEH) -ChampdenBRI -Foodservice Consultants Society International (FCSI) -European hygienic engineering & design group(EHEDG) For the clean anti-corrosion performance, stainless steel is no doubt the most ideal choice to a clean drainage system. Moreover, the durability of stainless steel is also one of the most basic elements in cleanliness aspects. The smoothness of the surface and easy cleaning performance of stainless steel material cannot be matched by other metal materials. When it comes to commercial kitchen or food processing industry, austenitic stainless steel 304 or 316 grade are generally used. Except the correct selection of the material itself, the thickness of the material also should be considered. For ground leakage body and drainage channels, 1.5-2.0mm stainless steel sheet is usually used for manufacturing. The cover plate need to be designed separately considering its loading capacity Since stainless steel products need to be cut and welded in machining process, the original anticorrosion layer of its surface will be damaged. On this ground, the final anti-corrosion treatment on its surface will be done on finished products. The most economical and effective treatment method is passivation immersion processing, which means putting the processed products into pickling pool of different types and concentrations in sequential order and soaking for a certain amount of time. In this way, a continuous layer of dense oxide film will be generated on the surface of stainless steel to barrier some harmful materials in the air or drainage that can corroded the stainless steel protected by the oxide film. Another common method is electrical polishing. Using this preservative treatment method, the stainless steel surface can become bright, and it is more applied for the cover plate and decoration purpose.

Equipment Corrosion During Urea Production In industrial production, urea is synthesized by liquid ammonia and carbon dioxide, following the below reaction formula under a pressure level of 14-25MPa and temperature of 180~210℃. Pre-reaction raw materials like carbon dioxide and ammonia have weak corrosion, so do post-reaction products urea and water. However, reaction intermediate products like ammonium carbamates can exert strong corrosive effects under high temperatures. Meanwhile, urea produced during synthesis reaction can generate cyanic acid and ammonium cyanate. In water, CNO- ionized from cyanic acid and ammonium cyanate have strong reducibility like chloride ions, damaging the oxidation film on the stainless steel surface. Due to the strong depassivation effect, even stainless steel containing Molybdenum can hardly resist its corrosion. Hence, it is not until the addition of corrosion inhibitor to the corrosive medium does stainless steel have wide application in urea production. Stainless Steel Application in Urea Production Stainless steel is generally selected as the material to make ammonia production equipment, ammonium nitrate production equipment, and urea production equipment. In some manufacturers` practical applications, different parts are using distinct stainless steel materials to achieve cost efficiency. Austenitic stainless steel 06Cr19Ni10 (304) is applied in the inside of ammonia converter, nitric acid preheater, low-pressure neutralizing tower, and inspissator. Austenitic stainless steel 022Cr17Ni12Mo2 (316L) is used for synthetic tower, high-pressure condenser and syringe. Austenitic stainless steel 022Cr25Ni22Mo2N(310MoLN) is chosen for the distributing pipes of stripping tower. 06Cr19Ni10(304) or 022Cr17Ni12Mo2(316L) is employed in prilling tower. 022Cr25Ni7Mo4N(2507) is harnessed in the body of ammonium carbamate pumps. Duplex stainless steel 03Cr25Ni6Mo3Cu2N(255) is used in valves; Austenite 12Cr18Mn9Ni5N(202) or 12Cr18Mn10Ni5Mo3N is leveraged for inner parts of urea synthesis tower, evaporator, nitric acid underground storage tank and ammonium nitride vacuum evaporator. Stainless steel 022Cr14Ni14Si4 is used to make concentrated nitric acid equipment such as evaporator and storage tanks. 022Cr17Ni5Si4N is used for manufacturing fuming nitric acid absorption tower, tankers, etc.

Definition: Super duplex stainless steel refers to those duplex steel with PREN >40 ( PREN is abbreviated from [Pitting Resistance Equivalent Number", a measurement of the corrosion resistance of stainless steel containing nickel), Cr 25%, (high) molybdenum >3.5%, and (high) nitrogen ranging 0.22%~0.30%. Features: Super duplex features higher corrosion resistance and better mechanical properties than duplex stainless steel 2205 (S31803). The main grades/types are UNS S32550 (UR52N+), S32750 (SAF 2507) and S32760 (Zeron 100), developed by CLI from French, SANDVIK from Swedish and MATER+PLATT from UK respectively. The deformed materials of these super duplex were invented in 1990 and 1991 sequentially, and launched into market in recent years. The chemical compositions of these three steels are quite similar; the main difference lies in the content of tungsten and copper. Chemical properties of super duplex stainless steel: Mechanical properties of super duplex stainless steel: Application: · 1) Offshore oil platform (heat exchanger tubes, water treatment and water supply systems, fire protection systems, water spray systems, water stabilization systems) · 2) Special chemical environmental equipment such as desalting (desalination) equipment (high pressure pipe in Ro equipment, seawater pipe) · 3) Oil and gas industry equipment · 4) Chemical processing industry, utensils and pipeline industry · 5) Desalting plants, submarine pipelines · 6) Mechanical components (high-strength and corrosion-resistant components), energy industry FGD systems, industrial scrubbing systems and absorption towers · 7) Others.

Introduction & Features S32750 (2507) is a duplex stainless steel that combines many excellent features of ferritic and austenitic steels. Due to its high chromium and molybdenum content, it embodies excellent resistance to pitting corrosion, crevice corrosion and uniform corrosion. The two-phase microstructure ensures that the steel has high resistance to stress corrosion cracking and high mechanical strength. Besides, it features strong resistance to chloride pitting, high thermal conductivity and low coefficient of thermal expansion. In comparison with S32205 duplex steel, S32750 features higher strength and corrosion resistance. Compared to 904L, it is more resistant to corrosion caused by dilute sulfuric acid mixed with chloride ions. In contrast with austenitic stainless steel, it features higher yield strength and lower ductility. S32750 super duplex steel also features high impact strength, not suitable for use under temperatures above 570 °F or 300 °C, in that long exposure to such environment will lead to reduced toughness. Workability S32750 needs to be solution annealed and quenched after hot forming or cold forming. When it is done with solution annealing, the temperature should not be lower than 1925 °F, and air or water quenching should be carried out immediately. In order to secure the desired corrosion resistance, the heat treated steel needs to be subjected to pickling and rinsing. S32750 features good weldability. Many common stainless steel forming methods are also suitable for S32750. It can be welded by a series of methods such as SMAW, GTAW, PAW, FCW, or SAW. When soldering S32750, it is advisable to use 2507/P100 metal, which will form a suitable two-phase structure. Chemical Compositions of S32750 Stainless Steel Mechanical Properties of S32750 Stainless Steel Application · 1) Desalted plants, high pressure RO plants and submarine pipelines; · 2) Offshore platforms, heat exchangers, underwater equipment, firefighting equipment and seawater treatment equipment; · 3) Chemical processing industry, utensils and pipeline industry; · 4) Mechanical parts (high-strength, corrosion-resistant parts); · 5) Oil and gas industry equipment; · 6) Corrosion resistant parts of chemical tankers; · 7) Energy industry FGD system, industrial scrubbing system, absorption tower; · 8) Refining, fertilizer and paper;

1. Color identification After pickling, the surface color of stainless steel is white and bright. The color of chromium-nickel stainless steel is white and like a jade; The color of chrome stainless steel is white and a bit gray, it also have a weak luster; The color of chromium-manganese-nitrogen stainless steel is similar to that of chromium-nickel stainless steel, but it is lighter. The surface color of unpickled stainless steel: Chromium-nickel steel is brown-white, chromium steel is brown-black, and chromium-chromium-manganese is black (these three colors refer to the heavier oxidized color). The surface color of cold-rolled unannealed chromium-nickel stainless steel is silver-white and reflective. 2. Identification with magnets Magnets can be leveraged to distinguish between two types of stainless steel. Because the chromium stainless steel can be attracted by the magnet in any state. The chromium nickel stainless steel is generally non-magnetic in the annealed state; after the cold working, some of them will be magnetic. However, manganese-rich steels with higher manganese content are non-magnetic. Chromium-nickel-nitrogen stainless steels have more complex magnetic properties: some are non-magnetic, some are magnetic, and some have a non-magnetic vertical surface and a magnetic transversal surface. Therefore, although magnets can basically distinguish between chromium stainless steel and chromium-nickel stainless steel, they cannot correctly distinguish some special-property steel grades, let alone distinguish specific grades or types of stainless steel. 3. Identification with copper sulfate Remove the oxide layer on the steel, put a drop of water and rub with copper sulfate. If it is not discolored after rubbing, it is generally stainless steel; If it turns purple, it can be one of the two results: 1) if it is non-magnetic, it is high manganese steel; 2) if it is magnetic, it is generally ordinary steel or low alloy steel. For steel grades of special property, we can adopt the following three methods for identification. 4. Grinding spark identification Grinding spark identification is to grind the stainless steel on the grinder and observe the spark. For example, if the spark is streamlined and has more dense knots, it is high manganese or manganese nitrogen steel with higher manganese content; if there is no knot, it is chrome steel or chrome nickel stainless steel. 5. Annealing identification If the cold-worked chromium-nickel stainless steel is magnetic, two methods can be used to verify it: take a small piece and burn it to red, then 1) let it cool naturally; 2) put it into water. In general, the magnetism will be significantly reduced or completely disappear after annealing. However, some chromium-nickel stainless steels, such as Cr18Ni11Si4AlTi steel and Cr21Ni5Ti steel are magnetic even in the hot working state, because they contain more ferrite elements and a considerable part in their internal structure are ferrite. 6. Chemical qualitative identification Chemical qualitative identification is a method of identifying whether magnetic stainless steels contains nickel. The method is to dissolve small pieces of stainless steel in aqua regia, dilute the acid solution with clean water, add ammonia water, and then gently inject the nickel reagent. If a red fluffy substance floats on the liquid surface, it means that the stainless steel contains nickel. If there is no red fluffy material, it proves lack of nickel in the stainless steel. Since the nickel content in stainless steel is relatively low with only a few percent, it may not be easy to perceive or determine the content. Generally, many times of standard sample experiments need to be done to determine the content.

Standards of Surface Processing Many surface processing technologies, classified by numbering or other methodologies, have been incorporated into relevant standards, such as the American Standard ASTM A484, the British Standard BS1449 and the European Standard EN10221. Rolling surface processing Basically, there are three rolling finishes for sheets and strips, expressed by their production processes. No.1 Finish Finish: The finishes of the treated sheets are dull and somewhat rough. Production Process: The sheets are hot rolled, annealed, pickled, and descaled. No.2D Finish Finish: No.2D is better than N0.1 finish, but it also presents a dull surface. Production Process: The sheets and strips are subjected to cold rolling, annealing, descaling, and finally light rolling with a matte roller. No.2B Finish Finish: The surface is slightly illuminated and allows for polishing treatment. Production Process: It is the most commonly used for architectural applications. The production process is similar to 2D finish; only No. 2B entails light cold rolling with a polishing roller after annealing and descaling for its last process. No. 2B Bright Annealing Finish Finish: This is a reflective surface. Bright annealing still maintains its reflective surface and does not produce oxide skin. Production Process: The sheet is rolled by a polishing roll and subjected to final annealing in a controlled atmosphere. Since the oxidation reaction does not occur during the bright annealing process, it eliminates the necessity to perform pickling and passivation treatment. Polished surface processing No. 3 Finish No.3 is represented by 3A and 3B. 3A finish is uniformly ground with the abrasive grain size at 80 to 100. 3B Finish Finish: The mill finish is polished, with uniform straight lines on the surface. Production Process: Usually, it is polished on the 2A or 2B sheet by the abrasive belt with grain size at 180-200 to get 3B finish. No.4 Finish Finish: No.4 or 4K finish is unidirectional and of low reflectivity, with the widest use for architectural applications. Production Process: The sheets are first polished with coarse abrasive and finally with abrasive grain size at 180. No.6 Finish Finish: No.6 Finish is a further improvement of No. 4, which is polished with a Tampico polishing brush in abrasive and oil media. No.4 finish is not available in British Standard 1449 but can be found in the US standard. No.7 Finish Finish: No.7 is known as bright polishing on the surface that has been ground very fine but still has scratch marks. Production Process: 2A or 2B plates are commonly used, with fiber or cloth polishing wheels and corresponding polishing pastes. No.8 Finish Finish: No.8, or 8K finish is often referred as mirror finish, because the image it reflects is sharp. Production Process: The stainless steel is usually polished continuously with fine abrasives and then polished with polishing pastes. Care should be taken when it is designed for architectural applications. Such stainless steel with 8K finish, if used in places where people are heavily mobile or where people often touch them, can be left handprints. Though the fingerprints can be erased easily, but sometimes it affects the appearance. Note The surface processing described in official standards and literature is quite general; only the sample can best show the type of surface processing. Polishing or metal finishing mills can provide samples of a variety of finishes for straightforward communications with their users. Surface roughness The classification of rolling surface processing and polishing surface processing is to illustrate the extent to which a surface can be processed; another effective method is to measure surface roughness. The standard measurement method is called CLA (center line average). Move the gauge laterally on the surface of the steel sheet to record the change in the peaks and valleys. The smaller the CLA number, the smoother the surface.

Introduction Quenching is a heat treatment process that involves heating steel to a temperature above the critical temperature Ac3 (hypoeutectoid steel) or Ac1 (hyper-eutectoid steel), preserving the heat for a period of time to allow for complete or partial austenitization of the steel, then cooling it off rapidly at a rate above the critical cooling rate, to a temperature below Ms for martensite (or bainite) transformation (or isothermal near Ms). From time to time, quenching also entails solution treatment of materials such as aluminum alloys, copper alloys, titanium alloys, tempered glass; or heat treatment involving rapid cooling processes. Purpose of quenching The purpose of quenching is to transform the undercooled austenite into martensite or bainite to obtain martensite or bainite structure; quenching associated with tempering at different temperatures can significantly improve the steel rigidity, hardness, wear resistance, fatigue strength, toughness etc., enabling the steel to meet various requirements of different mechanical parts and tools. Quenching can also give some special steels special physical and chemical properties such as ferromagnetism and corrosion resistance. Quenching is a metal heat treatment technology in which a metal workpiece is heated to a suitable temperature for a period of time and then immersed in a quenching medium for rapid cooling. Brine, water, mineral oil, air, and the like are the commonly used quenching media. As quenching can improve the hardness and wear resistance of metal workpieces, various tools, molds, measuring tools and parts that require surface wear resistance, such as gears, rolls, carburized parts, etc. will resort to this process. Through quenching and tempering at different temperatures, the strength, toughness and fatigue strength of the metal can be greatly improved. With these combined properties or enhanced comprehensive mechanical properties, the metal can meet different application requirements. In addition, through quenching, some special properties of steel can obtain certain physical and chemical properties, such as strengthened ferromagnetism for permanent magnet steel, and improved corrosion resistance for stainless steel. The quenching process is mainly used for steel parts. When the commonly used steel is heated above the critical temperature, the original structure at room temperature will undergo transformation that changes all or most of its microstructure into austenite. Then put the steel into the water or oil for rapid cooling and the austenite will be transformed into martensite. Martensite features the highest hardness compared to other steel structures. Keep noted that rapid cooling during quenching can cause internal stresses in the workpiece. If the stress is large enough, the workpiece will be distorted or even cracked. To avoid it, we must choose the right cooling method. Quenching application The quenching technology is widely used in the modern machinery manufacturing industry. Important parts in machinery, especially those used in automobiles, airplanes, and rockets, are all almost quenched. In order to meet the technical requirements of various parts, various quenching processes have been developed. For example, in light of the parts to be treated, there are integral quenching, partial quenching and surface quenching. Based on whether the phase transformation is complete under heating, there are complete quenching and incomplete quenching (for hypoeutectic steel, the method is also called subcritical quenching). According to the contents of phase change, there are step quenching, isothermal quenching and slack quenching.

Surface Treatment Methods and Effects on Stainless Steel Pipes Overview Stainless steel pipe finish varies with environments. Knowing how environment will affect stainless steel pipes can help us make the right choice on stainless steel types, otherwise stainless steel pipes will also suffer from rust and corrosion. Different stainless steel pipes call for distinct surface treatment, such as: • Pickled finish or sand blasting finish for stainless steel seamless pipe (industrial use); • Polished finish for stainless steel sanitary tubes (seamless); • Polished finish for small diameter stainless steel welded tubes; • Pickled finish or sand blasting for stainless steel welded pipes and tubes (industrial use); • Inside and outside polishing for stainless steel sanitary tubes (welded). Sand Blasted SS Seamless Pipe / Tube Polished SS Welded Pipe / Tube I & O Polished SS Sanitary Pipe / Tube Pre-treatments Pre-treatments like pickling, chemical brightening, electrochemical polishing, electroplate, passivation, black coating, color coating, chemical machining, are the important steps to do surface treatment on stainless steel pipes. Before stainless steel pipe taking shape, the surface is likely to have oils, burs, uneven surface and oxide, hence, these flaws should be removed before doing surface treatment. The dirt that needs to be removed from stainless steel pipe finish can be divided into organic matters and inorganic matters. Organic matters include mineral oil, such as diesel, machine oil, Vaseline, paraffin, animal oil and plant oil, such as bean oil, tea oil, colza oil, lard, and beef tallow. The greasy dirt is mainly lubricating oil, cutting oil, quenching oil, polishing oil, or fingerprints generated during stainless steel pipe processing. Inorganic matters include soil, dusts, compounds etc. generated during heat treatment. Stainless Steel Pipe Pre-treatment Procedures (1) Polishing: Removing the roughness of stainless steel surface, doing machine lapping and polishing to certain surface finish; (2) Degreasing: Removing the surface oil; (3) Pickling: Removing the oxide on the surface; (4) Weak corrosion: activate surfaces to be treated, remove the surface passivation film, exposing the metal crystal structure. Stainless Steel Pipe Surface-treatment Methods: Pickling Sand Blasting Polishing (1) Mechanical Method: use polishing machine or other machines to remove surface roughness. (2) Chemical Method: use alkaline solution to remove oil, acid solution to pickle, and organic solvent to dissolve grease and descaling. (3) Electrochemical Process: use electrochemical to remove oils and do electrochemical etching. (4) Roll finish, centrifugal roll finish, centrifugal pan brightening, rotation brightening, suitable for small pieces with effects of flattening and descaling. (5) Sand blasting: applying for large area treatment, with effects of decontamination and removing oxide skin. Hence, appropriate methods should be chosen as per the status of stainless steel pipe surface and the subsequent quality requirement.