Stainless steel knowledge

Release Time:

Jul 11,2024

Magnetic properties of austenitic stainless steel (standards: ISO 3506, GB/T3098.6) All austenitic stainless steel fasteners are usually non-magnetic; After cold processing, some magnetism may become apparent. The magnetization ability of various materials is also applicable to stainless steel. It is only possible to be completely non-magnetic in a vacuum state. The measurement of the magnetic permeability of materials in a magnetic field is equivalent to the magnetic permeability μ r of materials in vacuum. If μ r is close to 1, the material has low magnetic permeability. For example: A2:μr≈1.8 A4:μr≈1.015 A4L:μr≈1.005 F1:μr≈5 The strength of magnetism is closely related to the alloy composition of steel: Magnetic formula: MD30=551-462x (C+N) -9.2xSi-8.1xMn-13.7xCr-29x (Ni+Cu) -18.5xMo. The smaller the value, the smaller the magnetic properties.

Definition of stainless steel

Stainless steel usually refers to steel that has the ability to resist corrosion by air, water, acid, alkali salts or media. Depending on the alloy composition, stainless steel and acid resistance are respectively emphasized. Although some steels are stainless, they are not necessarily acid-resistant, while acid-resistant steels are usually stainless.

Classification of stainless steel

According to organizational structure: austenitic stainless steel, martensitic stainless steel, ferritic stainless steel, duplex stainless steel; According to the main chemical components of steel: chromium stainless steel, chromium-nickel stainless steel, chromium-nickel-molybdenum stainless steel, ultra-low carbon stainless steel. (Austenitic stainless steel is mainly used to produce fasteners. In people's daily life, the stainless steel often referred to is also austenitic stainless steel)

Austenitic stainless steel steel types and characteristics

It is non-magnetic under normal conditions and slightly magnetic after cold working. It can maintain its Ostian structure at various temperatures without phase change, so it cannot be hardened by heat treatment. However, cold working can harden it and increase its strength.

Austenitic stainless steel mainly includes the following steel types

Breaking torque of austenitic steel bolts and screws M1.6-M16 (coarse thread)（standard：ISO 3506，GB/T3098.6)

Mechanical properties of austenitic stainless steels at high temperatures and adaptability at low temperatures

If the bolt, screw or stud is calculated to be suitable, the matching nut will also meet the requirements. (The following data is for guidance only)

1. Mechanical properties at high temperatures:

Ratio of the values of the yield point σs and the specified non-proportional elongation stress σs at high temperature to the values at room temperature (expressed in %)

See Table 1:

Table 1: Temperature-affected σs and σs