The strength of stainless steel including tensile strength and yield strength is determined by various factors, but the most important and the most basic factor is the addition of different chemical elements, mainly metal elements. Different types of stainless steel due to the differences in their chemical composition, there are different strength characteristics.
1.Martensitic stainless steel
The martensitic stainless steel is the same as that of ordinary alloy steel, which can be hardened by quenching, so the mechanical properties can be achieved by selecting the grade and heat treatment conditions.
The variation of Cr, C, Mo and other elements in the martensitic CR system is described, and the strength characteristics of the elements such as carbon and molybdenum are added.Under the condition of quenching and tempering, the content of Cr increases with the increase of the content of Cr, which can decrease the hardness and tensile strength. Low carbon martensite chromium stainless steel in the annealing conditions, when the chromium content increased hardness increased, while the elongation rate decreased slightly. Under certain conditions of chromium content, the increase of the carbon content increases the hardness of the steel after quenching, and the plasticity decreases. The main purpose of adding molybdenum is to improve the strength and hardness of the steel and the effect of the two hardening. After low temperature quenching, the effect of molybdenum is very obvious. Content is usually less than 1%.
2.Ferritic stainless steel
According to the research results, when the chromium content is less than 25%, Ferrite microstructure will inhibit martensite, thus its strength decreased with increasing of Cr content; more than 25% of the solid solutions trengthening alloy, the strength was increased slightly. The increase of Mo content can make it easier to obtain ferrite, can promote the “alpha phase, and the precipitation of sigma Chi, and after the solution to improve its strength after reinforcement. But at the same time, the notch sensitivity is improved, so that the toughness is reduced. The effect of molybdenum on the strength of ferritic stainless steel is greater than chromium.
3.Austenitic stainless steel
Increased carbon content, solid solution strengthening improves the strength of austenitic stainless steel.
4..Duplex stainless steel
Mechanical properties research shows that the gamma phase also increases with increasing Ni content in the alpha + gamma dual phase region. When the chromium content in the steel is 5%, the yield strength of the steel reaches the highest value. When the nickel content is 10%, the strength of the steel reaches the maximum value.