Knowledge of stainless steel

1. In materials science, a series of iron based alloys with C<1.2%, Cr>10.5%, and corrosion resistance and rust resistance as the main performance are commonly referred to as stainless steel.

2. The main uses of stainless steel wire are: fasteners, welding rods, wire mesh, tableware, shafts, hardware, etc.

3. The structural classification of stainless steel can be divided into austenitic stainless steel, martensitic stainless steel, ferritic stainless steel, duplex stainless steel, and precipitation hardening stainless steel.

4. Non destructive testing methods for stainless steel include ultrasonic testing, liquid penetrant testing, eddy current testing, magnetic particle testing, etc.

5. Iron, chromium, and nickel are the three basic elements of austenitic stainless steel.

6. Ultra low carbon stainless steel refers to stainless steel with C ≤ 0.03%.

7. Regarding the surface treatment of stainless steel, it is called No.1 after hot rolling, heat treatment, and pickling; After cold rolling, heat treatment, acid pickling, and then finishing to make the surface moderately bright is called 2B; The bright annealed stainless steel surface is commonly referred to as BA.

8. The rust resistance and corrosion resistance of stainless steel are due to the formation of chromium rich oxide films on its surface.

9. There are two main forms of corrosion of stainless steel: uniform corrosion and local corrosion. The main types of common local corrosion are: intergranular corrosion, pitting corrosion, stress corrosion, and so on.

10. Stress corrosion cracking refers to the cracking caused by the combined action of stress and corrosion under specific media conditions.

11. Spot corrosion refers to the corrosion damage of local areas on the metal surface, which first forms corrosion pits, then develops internally, even throughout the entire section. It is a common corrosion state of stainless steel.

12. With the decrease of carbon content, the sensitivity of austenitic stainless steel to intergranular corrosion decreases, and the effect is most obvious when the carbon content is below 0.02%.

13. Sulfur is generally considered a harmful element in stainless steel, and can improve the cutting performance of free-cutting steels.

14. There are two process modes for casting stainless steel: mold casting and continuous casting.

15. In stainless steel smelting, the main metallurgical functions undertaken by the LF furnace are: adjusting temperature, adjusting composition, deoxidation, and desulfurization to make the molten steel meet the pouring requirements.

16. The main metallurgical functions of stainless steel continuous casting mold powder include thermal insulation, adsorption of inclusions, prevention of oxidation, lubrication, and heat transfer.

17. The five most common and harmful elements in stainless steel are lead, tin, antimony, bismuth, and arsenic.

18. The non-metallic inclusions in stainless steel mainly include sulfide, oxide, silicate, and nitride.

19. The main purpose of heating stainless steel before rolling is to improve plasticity and reduce deformation resistance to facilitate rolling.

20. During cold rolling, metal deformation resistance increases and rolling pressure increases. This phenomenon is known as work hardening.