Alloy Steel vs Stainless Steel: What’s the Difference?

Alloy steel and stainless steel are two common metal materials that are widely used in various fields, such as machinery, construction, chemical industry, and medical care. So, alloy steel vs stainless steel – what’s the difference? In this article, we will try to answer this question in detail.

Alloy Steel vs Stainless Steel: What’s the Difference?

Alloy Steel vs Stainless Steel – 1. Categories

According to the International Organization for Standardization (ISO), alloy steel and stainless steel can be classified into several categories based on their chemical composition and microstructure:

Alloy steel: mainly divided into low alloy steel and high alloy steel. Low alloy steel refers to the addition of a small amount of alloying elements such as manganese, silicon, copper, nickel, etc. to the ordinary carbon steel to improve its strength, toughness, and corrosion resistance. High alloy steel refers to the addition of more alloying elements such as chromium, nickel, molybdenum, vanadium, etc. to the ordinary carbon steel to improve its heat resistance, wear resistance, and special properties.

Stainless steel: mainly divided into austenitic, martensitic, ferritic, duplex, and bainitic types. Austenitic stainless steel refers to stainless steel with a chromium content of more than 18%, a nickel content of more than 8%, and a carbon content of less than 0.08%. It has good corrosion resistance, plasticity, and weldability.

Martensitic stainless steel refers to stainless steel with a chromium content of 12%~18%, a carbon content of more than 0.1%. It has high strength, hardness, and wear resistance.

Ferritic stainless steel refers to stainless steel with a chromium content of 10.5%~30%, a carbon content of less than 0.2%. It has good oxidation resistance and stress corrosion resistance.

Duplex stainless steel refers to stainless steel with a chromium content of 18%~28%, a nickel content of 3%~10%, and a small amount of molybdenum (Mo) and other alloying elements. It has the dual characteristics of austenite and ferrite.

Bainitic stainless steel refers to stainless steel with a chromium content of about 17%, a nickel content of about 4%, and alloying elements such as copper, aluminum, titanium, etc. It has adjustable strength and hardness.

Alloy Steel vs Stainless Steel – 2. Production Process

The production process of alloy steel and stainless steel is as follows:

Alloy steel: The process flow of steelmaking-rolling-heat treatment is mainly used, which involves melting iron and alloy elements in a converter or electric furnace, casting the molten steel into ingots or continuous casting billets, and then shaping it through plastic processing such as rolling or forging. Finally, subsequent processes such as heat treatment or surface treatment are carried out to improve its organizational structure and properties.

Stainless steel: The process flow of smelting-rolling-annealing-pickling is mainly used, which involves smelting iron and alloy elements in an electric furnace, casting the molten steel into continuous casting billets, then subjecting them to plastic processing such as rolling or drawing, and finally performing thermal treatment processes such as annealing or solid solution treatment to eliminate stress and homogenize the structure. Surface treatment processes such as pickling or polishing are then performed to remove oxide scales and enhance gloss.

Alloy Steel vs Stainless Steel – 3. Applications

The application scope of alloy steel and stainless steel is as follows:

Alloy steel: mainly applicable to fields with high requirements for material strength, toughness, corrosion resistance, heat resistance, wear resistance, etc., such as machinery manufacturing, automotive manufacturing, aerospace, nuclear industry, military industry, etc.

Stainless steel: mainly suitable for applications that have high requirements for material corrosion resistance, high-temperature resistance, aesthetics, etc., such as architectural decoration, food processing, medical equipment, chemical equipment, household appliances, etc.

Alloy Steel vs Stainless Steel – 4. Product Usage Scenarios

Typical product use scenarios for alloy steel and stainless steel are as follows:

Alloy steel: In automotive manufacturing, alloy steel can be used as the material for important components such as engine blocks, crankshafts, and connecting rods to improve their high-temperature resistance and wear resistance. In aerospace, alloy steel can be used as the material for key components such as rocket engines and spacecraft structural components to improve their high-temperature resistance and oxidation resistance. In the nuclear industry, alloy steel can be used as the material for core components such as nuclear reactor pressure vessels and control rods to improve their radiation resistance and corrosion resistance.

Stainless steel: In architectural decoration, stainless steel can be used as a beautiful and durable material for exterior walls, railings, doors, and windows. In food processing, stainless steel can be used as a hygienic and safe material for food containers, tableware, kitchenware, etc. In medical equipment, stainless steel can be used as a bio-inert material for surgical knives, scissors, forceps, bone nails, brackets, etc. In chemical equipment, stainless steel can be used as a material for reactors, heat exchangers, storage tanks, etc. that are resistant to acid and alkali organic compounds.

Conclusion

Thank you for reading our article and we hope it can help you have a better understanding of the difference between alloy steel vs stainless steel. If you want to learn more about stainless steel, we would advise you to visit Sino Stainless Steel for more information.

As a leading supplier of stainless steel products across the world, Sino Stainless Steel provides customers with high-quality stainless steel strips, stainless steel coils, stainless steel plates, stainless steel sheets, stainless steel bars, and stainless steel tubes at an extremely competitive price.