通过化学成分分析、断口宏微观形貌观察以及金相组织检验等方法，对液压壳体的开裂性质和开裂原因进行了分析。结果表明：液压壳体的开裂性质为应力腐蚀开裂。液压壳体的开裂原因是开裂处孔壁设计不符合堵头安装标准，导致堵头压入后，孔壁较薄处发生应力集中，薄壁处产生较大拉应力。同时，液压壳体在海洋环境中工作，受到氯、硫等腐蚀性元素的腐蚀作用，从而导致应力腐蚀开裂。

By chemical component analysis, macro and micro observation of fracture, and metallographic structure testing, the cracking mode and causes of a hydraulic shell were analyzed. The results indicate that the cracking of hydraulic shell was stress corrosion cracking. The causes of the cracking were as the follwing:first, the design of the hole wall did not meet the standerds of istallation, which led to stress concentration in the thin part of the hole wall and produced tensile stress when the plug was pressed in.Meanwhile, the hydraulic shell worked in the sea and was affected by corrosive elements like Cl and S and thus stress corrosion cracking happened.