Chemical analysis terms for steel pipes
 
This article introduces the third part of common terms in the technical requirements of steel pipes --- Chemical analysis terms for steel pipes
 
 
Chemical Analysis Terms
The chemical composition of steel is one of the important factors related to the quality of steel and end-use performance. It is also the main basis for formulating heat treatment systems for steel and even final products. Therefore, in the technical requirements of steel standards, the first item often specifies the grade (steel grade) and chemical composition applicable to steel, and is listed in the standard in the form of a table. It is the acceptance of steel and steel chemical composition by manufacturers and customers. Important basis.
 
1.Smelting 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 in the middle of pouring. In order to make it representative, that is, to represent the average composition of the furnace or tank, it is stipulated in the sampling standard method that the molten steel is cast into small ingots in a sample mold, and the sampling scraps are planed or drilled on the basis of the specified standards. The method (GB / T223) is used for analysis, and the results must conform to the standard chemical composition range, which is also the basis for customer acceptance.
 
 
2.Composition of finished product
The composition of the finished product is also called the verification analysis composition. It is a chemical composition obtained by drilling or planing the sampling scraps from the finished steel according to the prescribed method (GB / T222) and analyzing it according to the prescribed standard method (GB / T223). During the crystallization and subsequent plastic deformation of the steel, due to the uneven distribution (segregation) of the alloying elements in the steel, there is a deviation between the final product composition and the standard composition range (smelting composition). The deviation value should meet the requirements of GB / T222 .
 
 
3. Arbitration analysis
When the results of the analysis of the same sample by the two laboratories are significantly different and exceed the allowable analysis error of the two laboratories, or when the manufacturer and the user department, the demander and the supplier have different opinions on the analysis of the finished product of the same sample or the same batch of steel , Can be re-analyzed by a third-party authority with rich analysis experience, which is called arbitration analysis. The result of the arbitration analysis is the basis for the final judgment.