As stainless steel is one of the most widely used metal materials and comes in a variety of grades, buyers often face the challenge of selecting the appropriate grade. Below is a detailed explanation of the properties and applications of various stainless steel grades to help guide the selection process.
200 series: This series has poor corrosion resistance and is widely used as a cheaper alternative to the 300 series.
300 series
301: Has good ductility and is used for molded products. It can also be hardened quickly by machining. It has good weldability, and its wear resistance and fatigue strength are better than those of 304 stainless steel. It offers high strength and corrosion resistance and is used for molded products such as springs and electronic components.
302: Its corrosion resistance is similar to 304, but due to its relatively higher carbon content, it has better strength and is often used for architectural decorative parts.
303: By adding small amounts of sulfur and phosphorus, it is easier to cut than 304 and is most suitable for turning on lathes, and for bolts and nuts.
304: The general model and food-grade stainless steel, also known as 18/8 stainless steel. It is widely used across various industries, can directly contact food and water, and is used for water supply pipes.
309: Offers better temperature resistance than 304, withstanding temperatures up to 980°C. It is mainly used in boilers, chemical industries, etc.
316: A medical-grade stainless steel with better corrosion resistance than 304. It is the second most widely used steel grade, primarily in the food industry and surgical equipment. Molybdenum is added to give it a special corrosion-resistant structure. It is also known as "marine steel" due to its better chloride corrosion resistance compared to 304. SS316 is often used in nuclear fuel recovery devices. The 18/10 stainless steel grade typically meets this level of application.
316L: Has even better corrosion resistance and is mainly used in chemical processing equipment, refrigerant tanks, water supply pipes, etc.
321: Similar to 304, but with the addition of titanium to reduce the risk of weld rust, while maintaining other properties similar to 304.
400 series: Ferritic and martensitic stainless steel
408: Good heat resistance but weak corrosion resistance. It contains 11% Cr and 8% Ni.
409: The cheapest model (British and American standards), usually used for automobile exhaust pipes. It belongs to ferritic stainless steel (chrome steel).
410: A martensitic (high-strength chromium steel) with good wear resistance but poor corrosion resistance.
416: The addition of sulfur improves the processing properties of the material.
420: "Tool grade" martensitic steel, similar to high-chromium Brinell steel, and one of the earliest types of stainless steel. It is also used for surgical knives and can be polished to a high shine.
430: A ferritic stainless steel used for decorative purposes such as automotive accessories, kitchens, bathrooms, and household items. It has good formability but poor temperature and corrosion resistance.
440: A high-strength tool steel with a slightly higher carbon content, which can achieve higher yield strength after proper heat treatment. Its hardness can reach 58HRC, making it one of the hardest stainless steels. A common example of its application is "razor blades." There are three commonly used models: 440A, 440B, 440C, and 440F (easier to process).
500 series: Heat-resistant chromium alloy steel.
600 series: Martensitic precipitation hardening stainless steel.
630: The most commonly used precipitation-hardening stainless steel, also known as 17-4 (17% Cr, 4% Ni, and 18-20% chromium).
