Mechanical property is an important index to ensure the final performance of steel, which depends on the chemical composition and heat treatment system. In the steel pipe standards, according to the different requirements, the tensile properties and hardness, toughness index, as well as user requirements of high and low temperature performance, etc..

Tensile strength. The sample in the stretching process, the maximum force in  breaking the sample divided by the original cross-sectional area, the stress, known as tensile strength. It represents the maximum capacity of a metal material to withstand failure under tension.

Yield point. A metallic material having a yield phenomenon, the stress of the specimen in the course of stretching without increasing the force that can continue to extend, called the yield point. If the force decreases, the upper and lower yield points should be distinguished.

Elongation. In a tensile test specimen, the percentage of breaking from the standard after the increase in the length of the original gauge length, called elongation.

Section shrinkage. In the tensile test, the samples were broken after the reduction of shrinkage is the largest diameter and cross-sectional area of the original cross-sectional area percentage, known as shrinkage on cross section.

Hardness index. The ability of a metal material to resist the indentation of a hard object. According to the test method and the scope of application, hardness can be divided into Brinell hardness, Rockwell hardness, Vivtorinox hardness, shore hardness, micro hardness and high temperature hardness, etc..