1. physical properties of stainless steel
The specific resistance of austenitic stainless steel can reach 5 times that of carbon steel, and the linear expansion coefficient is about 50% larger than that of carbon steel. The linear expansion coefficient of martensitic stainless steel and ferritic stainless steel is roughly equal to that of carbon steel. The thermal conductivity of austenitic stainless steel is about 1/2 that of carbon steel. Austenitic stainless steels are usually non-magnetic. Austenitic stainless steel with low Cr equivalent and Ni equivalent will produce deformation induced martensite and thus produce magnetism when cold working deformation is large. The martensite and magnetism can be eliminated by heat treatment.
2. Mechanical properties of stainless steel
Martensitic stainless steel has the lowest hardness in the annealed state and can be quenched and hardened. The hardness in the tempered state in normal use decreases slightly. Ferritic steels are characterized by low impact toughness at room temperature. When heated at high temperature for a long time, the mechanical properties will further deteriorate, which may lead to 475 ℃ embrittlement σ Brittle or coarse grain, etc. Austenitic stainless steel has low yield ratio (40% ~ 50%) at room temperature, high elongation, reduction of area and impact absorption energy, and high cold work hardening. Some austenitic stainless steels will produce σ The embrittlement phenomenon caused by chromium carbide precipitated from phase and grain boundary. At low temperature, both Ferritic and martensitic stainless steels have low Charpy impact energy, while austenitic stainless steels have good low temperature toughness. For austenitic stainless steel containing a few percent ferrite, attention should be paid to the reduction of plasticity and toughness at low temperature.