Requirements on Quality Inspection for Forged Parts of Carbon Structural Steel, Stainless Steel and Heat Resistant Steel
Forged parts are important components in mechanical manufacturing and have a wide range of applications. Therefore, the detection of forged parts is extremely important in the production process. The inspection requirements for forged parts are varied, depending on the material and process requirements of the forged parts. In this paper, the quality inspection requirements of carbon structural steel, stainless steel and heat-resistant steel forgings are discussed in detail.
Forged parts made of carbon structural steel, stainless steel and heat-resistant steel have many requirements for their material quality. Carbon structural steels are widely used in machinery manufacturing with a wide range of heat treatment performances. The material composition of carbon structural steels is expressed by chemical composition symbols or graphical symbols, and their mechanical properties and physical properties are expressed by specific performance parameters. For carbon structural steel forgings, when performing quality inspection, chemical composition analysis, mechanical properties test and steel grade identification test should be conducted according to relevant standards. Stainless steel and heat-resistant steel forgings generally have higher requirements for chemical composition and mechanical properties than carbon structural steel forgings, and surface characteristics should also be inspected. Chemical compositions such as C, Si, Mn, P, S, Cr, Ni, Mo, Nb, Ti, V, Al and B should be tested, and their content should meet the chemical composition requirements of the standard. The chemical element content of steel parts should be tested by spectroscopic analysis. The inspection items for the mechanical properties of stainless steel and heat-resistant steel forgings mainly include tensile strength, yield strength, elongation and reduction of area, impact test, hardness test, etc. Hardness testing is an important test method for detecting the surface performance and core performance of stainless steel and heat-resistant steel parts after heat treatment. The hardness test results should meet the requirements of the standard.
The grain size of the stainless steel and heat-resistant steel forgings after heat treatment affects the performance of the parts. It is usually determined by measuring the grain size. The grain size of stainless steel forgings should meet the requirements of the standard. In addition, bubbles, slag inclusion, welding, residual stress and other tests should be carried out according to the standard requirements.
In the heat treatment process of carbon structural steel, stainless steel and heat-resistant steel forgings, the surface characteristics such as decarburization, subcutaneous folding and filling welding should be checked. These surface characteristics affect the integrity and strength of the parts. During normal inspection, the surface characteristics are generally checked by manual or optical instruments to see if there is seepage, slag inclusion, cracks, folding and so on.
In addition to the two types of inspections mentioned above, non-destructive testing (NDT) should also be conducted to evaluate the internal quality of stainless steel, heat-resistant steel and carbon structural steel forgings. Such as magnetic particle testing, liquid penetrant testing, X-ray testing, ultrasonic testing, eddy current testing, etc. The aim is to detect the presence of internal structure defects such as shrinkage, shrinkage, inclusions, cracks, and assess the safety performance of the parts.
In summary, the quality inspection requirements of carbon structural steel, stainless steel and heat-resistant steel forgings are various, and they are both material performance and non-destructive detection. In the test process, qualified personnel should operate strictly according to the relevant standards and requirements to ensure the quality of the parts.
