Views: 118 Author: Good Du Publish Time: 2023-03-31 Origin: Site
ASTM A403 butt weld pipe fittings is made by stainless steels with austenitic structure at room temperature. Steady austenite structure exists in steels containing about 18% Cr, 8%~25% Ni and 0.1% C. Austenitic chromium-nickel stainless steels include the well-known 18Cr-8Ni steel and the high Cr-Ni series steel developed on this basis by adding elements such as Mo, Cu, Si, Nb and Ti. Austenitic stainless steels are non-magnetic and have high toughness and plasticity, but have low strength and cannot be strengthened by phase transformation, they can only be strengthened by cold working. Austenitic stainless steel is the most popular and widely used around the world.
Type of Stainless Steels
Austenitic Stainless Steels
Ferritic Stainless Steels
Duplex Stainless Steels
Martensitic Stainless Steels
Precipitation Hardening
Comparison of Properties of Different Types of Stainless Steel
| Alloy Group | Magnetic Response | Work Hardening Rate | Corrosion Resistance | Hardenable | Ductility | High Temperature Resistance | Low Temperature Resistance | Weldability |
| Austenitic | Generally No | Very High | High | By Cold Work | Very High | Very High | Very High | Very High |
| Duplex | Yes | Medium | Very High | No | Medium | Low | Medium | High |
| Ferritic | Yes | Medium | Medium | No | Medium | High | Low | Low |
| Martensitic | Yes | Medium | Medium | Quench & Temper | Low | Low | Low | Low |
| Precipitation Hardening | Yes | Medium | Medium | Age Harden | Medium | Low | Low | High |
Characteristics of Austenitic Stainless Steel Butt Weld Fittings
Corrosion Resistance
Chromium in the alloy forms a self-repairing protective transparent oxide layer. This oxidation layer makes stainless steel corrosion resistant. Even if the material surface is cut or damaged, it will repair itself and maintain corrosion resistance. Corrosion of stainless steel butt weld pipe fittings of different grades varies with the environment. Select the appropriate austenitic stainless steel grade according to the service environment. Increasing some elements reduces the corrosion resistance of stainless steels. Chloride especially adversely affects the corrosion resistance of austenitic stainless steels.
Cryogenic Toughness
Cryogenic toughness is measured by ductility or toughness at temperatures below zero. At low temperatures, the tensile strength of austenitic stainless steel is much higher than that of normal temperature and maintains good toughness.
Work Hardening Rate
Austenitic stainless steel can significantly improve the metal strength by cold working. It can be cold worked and annealed to increase the strength of specific components manufactured.
Hot Strength
Austenitic stainless steels retain high strength at high temperatures, especially the grades containing high levels of chromium, silicon, nitrogen and rare earth elements.
Improve Performance by Chemical Composition
Mo is added to improve pitting and crevice corrosion resistance;
Decrease C or add Ti or Nb to reduce the tendency of intergranular corrosion;
The addition of Ni and Cr improves the high temperature oxidation resistance and strength;
The stress corrosion resistance is improved by adding Ni.
Adding S and Se to improve cutability and surface accuracy of components
Austenitic Stainless Steel GradeS Promotion Relationship
