Tensile test (tensile test) is a test method for measuring material properties under axial tensile load. The elastic limit, elongation, modulus of elasticity, modulus of elasticity, ratio limit, area shrinkage, tensile strength, yield point, yield strength and other tensile properties can be determined by the data obtained by tensile test. Tests to determine a series of properties of materials under tensile loading, also known as tensile tests. It is one of the basic methods for testing the mechanical properties of materials, mainly used to check whether the materials meet the required standards and study the properties of materials. A series of strength and plasticity indexes can be determined by tensile test. Strength usually refers to the ability of a material to resist elastic deformation, plastic deformation and fracture under external forces. When a material is subjected to tensile loading, the phenomenon that plastic deformation continues to occur without increasing the load is called yield. The stress at the time of yielding is called the yield point or the physical yield strength, expressed by_S (Pa). In engineering, many materials have no obvious yield points, and the residual plastic deformation of the material is usually deformed into 0.2% stress values as yield strength, which is called the conditional yield limit or conditional yield strength, and is expressed in sigma 0.2. The maximum stress of a material before fracture, called tensile strength or strength limit, is expressed by_b (Pa). Plasticity refers to the ability of metal materials to produce plastic deformation without failure under load. The commonly used plastic indexes are elongation and section shrinkage. Elongation, also known as elongation, is the percentage of the total elongation to the original length ratio of the material sample after tensile load fracture, expressed in delta. The section shrinkage ratio is the percentage of the area reduced by the section to the area of the original section after the specimen is pulled apart under tensile load, expressed by_. The conditional yield limit_0.2, strength limit_b, elongation Delta and section shrinkage_are the four performance indexes which are often measured in tensile tests. In addition, the elastic modulus E, proportional limit_p and elastic limit_e of the material can also be measured.