An important basis for the acceptance of seamless pipes - chemical composition

The chemical composition of the seamless pipe ultimately determines the performance of the product, and it is also an important indicator when customers choose seamless steel pipes, and it is also an important basis for customers to accept products. The chemical composition of seamless steel pipe consists of two parts: smelting composition and finished product composition. The chemical composition of seamless steel pipe mainly includes: C, Si, Mn, P, S, Cr, Mo, Ni, Cn, Al, W, V, Ti, B, Nb, As, Sn, Sb, Pb, Bi.

The chemical composition also determines the performance of the seamless pipe, and there are three main methods for testing the performance: tensile test, impact test, hardness test and hydraulic test.

①Smelting composition of steel
The chemical composition specified in the general standard refers to the smelting composition. It refers to the chemical composition of steel after smelting and mid-casting. In order to make it representative, the analysis is carried out according to the specified standard method, and the result must meet the standard chemical composition range, which is also the basis for customer acceptance.

②Product composition
The composition of the finished product is also called the verification analysis composition, which is the chemical composition obtained by drilling or planing the sample chips from the finished steel according to the prescribed method, and analyzing it according to the prescribed standard method. During the crystallization and subsequent plastic deformation of steel, due to the uneven distribution (segregation) of alloying elements in the steel.

The composition of finished steel products is mainly used by the user department or quality inspection department to check and accept the quality of steel products. Manufacturers generally do not conduct finished product analysis (except for those required by users), but they should ensure that the finished product analysis meets the standards.

③ Arbitration Analysis

When there are significant differences in the results of the analysis of the same sample by two laboratories and exceed the allowable analysis error of the two laboratories, or when the manufacturer and the user department, the buyer and the supplier have different opinions on the analysis of the same sample or the finished product of the same batch of steel , can be re-analyzed by a third-party unit with rich analysis experience, which is called arbitration analysis. The results of the arbitration analysis shall be the basis for the final judgment.