300 series (chromium-nickel series): representative of the steel grade 304
300 series stainless steel use
301: The content of Cr and Ni is lower than 304, the tensile strength and hardness are increased by cold rolling, and it has certain magnetic properties after cold rolling. Mainly used in trains, aircraft, vehicles, springs, conveyor belts, screens, etc.
304: The most commonly used steel grade. Good corrosion resistance, heat resistance, low-temperature strength, and mechanical properties. Good processing performance at room temperatures such as deep drawing and bending. No hardening occurs after heat treatment. (Non-magnetic, operating temperature -196~800℃), widely used in various industries, such as household products (tableware, indoor pipes, water heaters, boilers, bathtubs), auto parts, medical equipment, building materials, chemicals, food industry, agriculture, Ship parts, etc.
304J1: Because of the addition of Cu, its formability, especially wire drawing, and anti-aging cracking properties are better, so it can be formed into products with complex shapes; its corrosion resistance is basically the same as 304. Mainly used in vacuum flasks, kitchen sinks, pots, pots, insulated lunch boxes, door handles, textile processing machines, etc.
304L: Low carbon 304 steel, corrosion resistance is similar to 304 in a normal state, but good intergranular corrosion resistance after welding or stress relief, corrosion resistance is retained without annealing after processing, generally below 400℃ Use (non-magnetic, use temperature -196℃~800℃). It can be applied to machinery, building materials, heat-resistant parts, and products with high requirements for intergranular corrosion resistance in the chemical, coal, and petroleum industries.
304/DQ/DDQ: DDQ refers to materials used for deep drawing (punching) purposes. Compared with 304, the other elements of 304/DDQ have not changed, but the content of Ni is increased by half to one, and the deep drawing and deep drawing are better. , Which is what we call “soft material”, but the polishing performance is slightly worse. Compared with 304, the content of Cr in 304/DQ is increased by half to one, and the polishing performance is better. Compared with DDQ, DQ has relatively poor deep drawing performance. It is mainly used for products that can be obtained without stretching, such as spoons, spoons, forks, electrical appliances, steel pipes, and so on. But it has an advantage compared with DDQ material, that is, BQ (polishing performance) is relatively better, which is mainly due to its slightly higher hardness. DQ is generally mainly used for materials other than DDQ purposes.
309S, 310S, 316L, 321: commonly known as heat-resistant steel, mainly used for the production of boilers, steam turbines, industrial furnaces, aviation, petrochemical, and other industrial sectors that work at high temperatures.
321: Ti is added to 304 steel, so it has excellent intergranular corrosion resistance, high-temperature strength and high-temperature oxidation resistance, high cost, and processing performance are worse than 304. Used in heat-resistant materials, automotive aircraft exhaust pipes, boiler cover chemical devices, heat exchangers, etc.
316L: Adding molybdenum to stainless steel, the overall performance is better than 304 and 310. Under high-temperature conditions, when the acid concentration is lower than 15% or higher than 85%, 316L has a wide range of uses. In intermittent use below 1600 degrees and continuous use below 1700 degrees, 316L has good oxidation resistance. Used in heat exchangers for pulp and papermaking equipment, dyeing equipment, film washing equipment, pipelines, and exterior materials for buildings in coastal areas, etc.
309S: It can withstand repeated heating below 980 degrees, has high-temperature strength, oxidation resistance, and carburization resistance, and is generally used for furnace materials.
310S: Suitable for making various furnace components, the highest temperature is 1200 degrees, the continuous use temperature is 1150 degrees, and it can be used for furnace materials, automotive purification equipment materials, etc.
Note: 304DQ/DDQ deep drawing material/super deep drawing material
200 series (chromium manganese nitrogen series):
representative steel grade 201 201: the previous national standard grade 12Cr17Mn6Ni5N, its appearance is mainly used to replace 304, but with the advancement of technology and further reduction of costs, steel mills continue to reduce the nickel content. 200 series stainless steel is widely used in the market at present, and the common products are LA, LH, L1, L4, etc. mainly produced by Guangzhou Lianzhong. The specific composition of these steel grades is as follows:
| Steel Grades | Ni | Mn | N | C | Si | P | S | Cr | Cu | Remarks |
|---|---|---|---|---|---|---|---|---|---|---|
| LH | 0.35 | 9.95 | 0.154 | 0.088 | 0.51 | 0.041 | 0.002 | 14.45 | 1.37 | Lianzhong |
| LA | 0.67 | 9.94 | 0.144 | 0.077 | 0.49 | 0.035 | 0.001 | 14.56 | 1.1 | Lianzhong |
| L1 | 1.12 | 9.3 | 0.148 | 0.073 | 0.61 | 0.046 | 0.002 | 14.41 | 1.43 | Lianzhong |
| L4 | 4.12 | 7.93 | 0.065 | 0.045 | 0.5 | 0.035 | 0.002 | 14.65 | 1.45 | Lianzhong |
The use of Lianzhong 200 series stainless steel: According to the above analysis, 200 series stainless steel can be formed through deep processing and can be widely used. Combined with the corrosion resistance of 200 series stainless steel, it is mainly used in decorative pipes, kitchenware, tableware, home appliances, food machinery, computer accessories, containers, etc.
Due to the poor recyclability of the 200 series products and a great waste of resources, many countries have halted the production of the 200 series. China has also canceled the 200-series national standard, and it is only a matter of time before the production of the 200-series is banned. In addition, the 200 series contains manganese, which is a heavy metal that is toxic to the human body.
After long-term use, it is enriched in the human body and causes chronic poisoning. The corrosion resistance of the 200 series is worse than that of the 300 series and 400 series, but the formability is better. The 200 series is still widely used, mainly because the 200 series is well-formed, does not contain magnets, and is cheap.
3. 400 series (chromium series):
The most obvious feature of the 430 400 series stainless steel representing the steel grade is that it does not contain nickel. Among them, ferritic stainless steel is also magnetic, so it is also called stainless steel. The 400 series stainless steel includes ferritic stainless steel and martensitic stainless steel. Ferritic stainless steel refers to low-carbon chromium stainless steel with more than 14% chromium and any chromium stainless steel with 27% chromium.
Because of its high chromium content, ferritic stainless steel has good corrosion resistance and oxidation resistance, but its mechanical properties and process properties are poor. It is mostly used for acid-resistant structures with little stress and as anti-oxidation steel. Martensitic stainless steel refers to chromium stainless steel with a chromium content of about 12%.
Because there is no free ferrite in the structure, the mechanical properties are higher than the above-mentioned steels, but the overheat sensitivity during heat treatment is lower. 400 series stainless steel also appeared to replace 300 series stainless steel. With people’s in-depth research on ferrite stainless steel and continuous improvement and perfection of technology in production and application, the use of modern stainless steel technology to produce low-carbon, ultra-low-carbon, and Modern ferritic stainless steels such as high-purity and ultra-pure ferritic stainless steels have been greatly improved and improved in quality.
Therefore, modern ferritic stainless steel is widely used in various fields closely related to people’s lives, such as household appliances, kitchen equipment, transportation, environmental protection, and municipal construction.
Uses of 400 series stainless steel:
Since 400 series stainless steel was developed to replace 300 series stainless steel, 400 series steel grades have been developed in a targeted manner. Examples: 409L, 439: It is the heat-resistant steel in the 400 series, which can be used in higher temperatures, such as low-temperature boilers and automobile exhaust pipes. In addition, 409L is also widely used in elevator cars to replace 304.
410 series: 410S (0Cr13), 410 (1Cr13), 420J1 (2Cr13), 420J2 (3Cr13) because of its low cost, machinability, and excellent mechanical properties, it is widely used in place of 304 and used in tableware and kitchen utensils.
443, 444: 443 stainless steel improves the high temperature pitting corrosion resistance by increasing Cr, reducing C, and adding Ti. At present, the corrosion resistance, processing performance, and welding performance of TTS443 have reached the level of 304. 444 by adding Mo, so the steel has good resistance to pitting, crevice corrosion, and stress corrosion, and is even better than SUS304 and SUS316 in some areas. The addition of Ti makes the steel have good intergranular corrosion resistance and high-temperature oxidation resistance. 444 is mainly used to manufacture water tanks, solar water heaters, heat exchangers, stress corrosion resistance equipment, etc.