Common methods for quality inspection of steel forgings
Nov. 30, 2020
(1) Chemical composition inspection
Generally, the chemical composition of the forging blank is not inspected, and its chemical composition is subject to the sampling and analysis in front of the furnace during smelting. But for important or questionable forgings, some chips can be cut from the forgings, and chemical analysis or spectral analysis can be used to check the chemical composition.
(2) Appearance shape and size inspection
Use visual inspection, template or marking methods to check the surface defects, shape errors and size of the forgings to determine whether the forgings meet the requirements of the pattern size.
3) Macro organization inspection
Macroscopic structure inspection is also called low magnification inspection. It uses the naked eye or a magnifying glass not greater than 10 times to inspect the macroscopic structure of the surface or section of the forging. The main methods include sulfur marking, hot acid leaching, cold acid leaching and fracture.
(4) Microstructure examination
Microstructure inspection, or metallographic inspection, is to observe, identify and analyze the microstructure state and distribution of forgings under an optical microscope, thereby helping to understand the relationship between microstructure and forging properties. Metallographic inspection can also show segregation and the distribution of some compounds in addition to the microstructure, and can be used to grade grain size and non-metallic inclusions.
(5) Ultrasonic flaw detection
Ultrasonic inspection is a non-destructive inspection, which is to check the internal or surface defects of the forging without damaging the forging. In addition to ultrasonic testing, there are magnetic testing, radiographic testing, etc. Because ultrasonic flaw detection has the advantages of high penetration, high sensitivity, simple operation, fast speed, and harmless to human body, it has become the main method for checking internal defects of large forgings.