How to check the Machinery Castings defects
To ensure the quality of Machinery Castingss, Machinery Castingss should be based on different uses and requirements, using different inspection methods, the timely detection of defects that are not allowed. Defect inspection generally adopted the following methods.
(A) the appearance of the inspection of the surface roughness of the inspection should be in the appropriate light conditions to visual – hand touch block, with the sense of the surface condition of the identification, with the measurement tool to obtain the Machinery Castings size data, statistical methods to determine the accuracy of the Machinery Castings Defect rate.
(B) chemical analysis of all Machinery Castingss, chemical composition is very important, so in most cases, the chemical composition is the acceptance index. Chemical composition also indirectly determines the mechanical properties of the Machinery Castings and the occurrence of defects or not.
(3) mechanical performance test Hardness test is the first to test whether the defect occurred in the Machinery Castings means, the beginning of this century, the United States was in the sand section of the test piece of Machinery Castings Machinery Castings cylinder head, such as hardness exceeds a certain value that is inevitable cracks To be scrapped. This method is simple and unusual.
(4) metallographic examination (metallographic microscope test) with an optical microscope and then magnified 50 ~ 2000 times to observe the polished metal surface, the sample in the absence of erosion under the conditions of inclusions (using bright, dark and polarized, interference And micro hardness and other functions with reference to GB10561-89 rating), after erosion of the organization and grain size inspection. This method is widely used to check microscopic defects, but also commonly used to study the microscopic characteristics of macroscopic defects.
(5) Non-destructive testing (non-destructive testing) Among them, the osmotic testing method (ISO3452), magnetic particle testing method, eddy current testing method, can only be used for Machinery Castings surface or surface part of the defect inspection, inspection of deep defects in the Machinery Castings, Line transmission method (ISO5579), tomography and ultrasonic flaw detection method. Nondestructive testing has developed rapidly in recent years, thanks to data processing and hardware tends to be portable, greatly improving the reliability and flexibility of inspection.