Stainless steel can be divided into three categories - austenite, ferrite, and martensite
Austenite grade
Suncor stainless steel mainly uses 304 series 316 and 300 grade stainless steel. 304 and 316 grades are the most important and widely used members of the austenite family. Austenite grades are usually non-magnetic and can only be hardened through cold work. However, they can have magnetism to a small extent, especially in molded parts. They can be softened by annealing heat treatment.
Ferrite grade
Suncor stainless steel typically does not use ferritic grade stainless steel. The ferrite grade has magnetism and is not hardenable.
Martensite grade
The martensite grade can be hardened by heat treatment and has magnetism. The main applications of varieties such as 440 are products that must resist atmospheric oxidation, mild corrosive chemicals, and wet or dry corrosion. This type contains up to 1% carbon. Suncor uses this type in certain products, such as quick connect wedges, but these components are coated to prevent further corrosion.
Typical content of stainless steel
Nickel - stabilizes the austenite structure, improves formability, enhances ductility, high-temperature strength, and corrosion resistance (especially in industrial and marine atmospheres, chemicals, food, and textile processing industries).
Silicon - improves anti scaling properties and prevents high-temperature carburization.
Manganese - improves hot working performance, increases yield rate and tensile strength (over 2%), partially replaces nickel, and stabilizes austenite structure.
Molybdenum - improves corrosion resistance (especially in sulfite, sulfate, acetic acid and acetate solutions, as well as salt water atmospheres), increases creep resistance, increases strength at high temperatures, expands passivation range, and counteracts pitting tendency.
Titanium, niobium, and tantalum - prevent intergranular corrosion by stabilizing carbon into titanium or niobium carbide instead of chromium carbide, resulting in finer grain size and reducing tensile strain during 430 type stretching and forming.
Sulfur, phosphorus, and selenium - improve processability.
Extra chromium - increases scaling, wear resistance, corrosion resistance, and enhances tensile strength.
Types and grades of stainless steel
Austenitic
301 type: contains less chromium and nickel than 302, used for more work hardening.
Type 302: It is the basic type of the 300 series, 18% chromium -8% nickel family. It is the famous 188 stainless steel, which is the most widely used among chromium nickel stainless steel and heat-resistant steel.
Type 303: Contains added phosphorus and sulfur for better processing characteristics. The corrosion resistance is slightly less than 302/304.
303Se type: containing Se and P to improve machinability.
304/304L type: Increase chromium and nickel, reduce carbon to reduce carbide precipitation and increase corrosion resistance. In welding applications, 304L has the lowest carbon content.
Model 305: Added nickel, reduced work hardening performance.
309/309S type: With the addition of chromium and nickel, it has stronger corrosion resistance and high-temperature scaling resistance. 309S contains less carbon, which can minimize the precipitation of carbides.
310S type: The nickel content is higher than 309/309S, which can further improve the anti scaling performance. The carbon content of 310S is lower than 310, which can minimize the precipitation of carbides.
316 type (casting 316 referred to as CF8M) and 316L type (casting 316L referred to as CF3M): contain a large amount of molybdenum additives to improve corrosion resistance (especially pit corrosion), creep resistance, and high-temperature strength. The carbon content in 316L is low, making it suitable for welding and also reducing corrosion.
321 type: contains titanium, which can stick carbon and avoid chromium carbide precipitation during welding.
330 type: The ultra-high nickel content can provide the best corrosion resistance for most furnace atmospheres. This brand has low coefficient of expansion, excellent ductility, and high strength.
Type 347-348: Add niobium tantalum to bind carbon and avoid chromium carbide precipitation during welding. Suitable for temperatures ranging from 800 to 1650 degrees Fahrenheit.
Ferrite
Type 405: Contains 12% chromium and added aluminum to prevent hardening.
430 type: It is the basic type in the ferrite family, with good ductility and excellent resistance to atmospheric corrosion. In intermittent use, its anti scaling performance is higher than 302, and slightly lower during continuous use.
430F/430Se type: sulfur and selenium are added separately to improve processability.
Type 442: Added chromium to improve anti scaling performance.
Type 446: has a higher chromium content (27%) to increase anti scaling properties, making it the highest among standard pure chromium types. Alloys with chromium content exceeding 30% become too brittle to be processed.
Martensite
410 type: It is a basic martensitic type. It is a universal corrosion-resistant and heat-resistant chromium stainless steel. It can harden to a wide range of mechanical properties through heat treatment. It can be soft annealed for cold drawing and forming. This level always has magnetism.
403 type: It is a special high-quality steel used for blades and buckets of compressors in steam turbines and jet engines. This brand is particularly suitable for parts with very high stress. This material is magnetic under all conditions.
416/416Se type: It is an improved version of 410 type and is a free machining, non jamming, and non wear alloy. These characteristics are obtained by adding sulfur or selenium to the 410 type. This is a heat-treatable grade with corrosion resistance and other characteristics, very close to the 410 type.
420 type: It is a chromium stainless steel that can undergo heat treatment, with a maximum hardness of about 500 Brinell. It only has maximum corrosion resistance under completely hardened conditions. The 420 model is magnetic under all conditions.
Type 431: It is a nickel bearing (1.252.00%) chromium stainless steel that can be heat treated to high mechanical properties. It is magnetic under all conditions of use. It has excellent corrosion resistance to types 410, 416, 420, 430, and 440 stainless steels.
440C type: It is a type of stainless steel that can be heat treated to the highest hardness of any stainless steel.