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1·The surface tiny crack generating by sample hardening were found in test, and some surface fracture caused by inclusion and gas pocket, and these appearance should be correctly analyzed and judged.

飞机发动机减速器支撑杆在加工过程中易产生微裂纹，通过显微组织检验、断口形貌观察、微区成分分析以及含氢量测定和模拟焊接试验等方法对其裂纹产生的原因进行了分析。

2·Making use of the principle that the sonic wave made by the rock open fracture spread in the rock, can accurately test the crack's appearance directions and extend length.

利用岩石张裂时发出的声波在岩石中的传播原理，可准确测出裂缝的形态方位和延伸长度。