工程机械结构庞大，有些部件的壳体在铸造过程中常存在气孔、疏松和夹砂等质量缺陷，虽然在使用前经过探伤检查和耐压试验，但在使用过程中，由于腐蚀及交变荷载的作用，缺陷处产生应力集中，会使铸件缺陷逐渐扩大，从而导致渗漏，如柴油机油底壳、水箱、变速器壳等。经过实践 Large construction machinery, some parts of the shell in the casting process often exist porosity, porosity and sand and other quality defects, although after the use of flaw detection and pressure test, but in the course of use, due to corrosion and alternating load Role, defects at the stress concentration, casting defects will gradually expand, resulting in leakage, such as diesel oil pan, water tank, transmission shell. After practice