Mechanical propertise of steel

Yield point (σs) -------- The phenomenon that the steel or sample continues to undergo significant plastic deformation when the stress exceeds the elastic limit during stretching, even if the stress is no longer increased, is called yield, and the minimum stress value at which the yield phenomenon occurs is the yield point. Set Ps as the external force at the yield point s and Fo as the specimen sectional area, then the yield point σs =Ps/Fo(MPa), MPa as MPa is equal to N (Newton) /mm2, (MPa =106Pa, Pa: PASCAL =N/m2 Yield strength (σ0.2) --------- The yield point of some metallic materials is not obvious and difficult to measure, so in order to measure the yield characteristics of the material, the stress when the permanent residual plastic deformation is equal to a certain value (generally 0.2% of the original length) is specified, called the conditional yield strength or yield strength σ0.2 Tensile strength (σb) ---------- The maximum stress reached by a material during the tensile process from the beginning to the time of fracture. It indicates the steel's ability to resist breaking. Corresponding to the tensile strength are compressive strength, bending strength and so on. Pb is the maximum tensile force achieved before the material is broken, Fo is the specimen cross-section area, then the tensile strength σb= Pb/Fo (MPa).