应力环加载装置对抗SSC试验结果的影响分析

Analysis of Influence on Result of SSC Test by Stress Ring Loading Device

抗硫化物应力腐蚀试验使用应力环对腐蚀试样轴向施加一个恒定的载荷,试验中发生试样未到规定时间就发生断裂的现象,观察断口的宏观特征为脆性断裂,断口平直,属于拉伸断裂。分析原因是应力环环体没有固定,加载时试样夹持装置的上下夹具中心线与试样轴线存在重合度偏差,同轴度误差使试样加载产生扭转载荷,导致试样早期断裂失效。建议在应力环加载试验中,固定应力环环体底座,设置调节螺栓专用卡槽,采取数字显示百分表准确显示加载位移,降低试验因素引起的试样断裂失效。

During the SSC test,when a constant load is imposed by the stress ring on the specimen,afterwards the specimen fails before the specified time.The macro characteristics of the specimen fracture as observed is of the kind of brittle fracture,and the fracture proper is flat,and is regarded as tensile fracture.The reasons as follows for such failure are identified via the analysis.The stress ring proper is not fixed,and thus when loading,there exists coincidence deviation between the centerline of the upper and lower fixtures of the specimen clamping device and the axis of the specimen,and then the coaxiality error gets torsional load produced when the specimen is loaded,which inevitably leads to the early stage fracture of the specimen.Accordingly in order to reduce the frequency of the specimen failure as caused by relevant test involved factors,it is suggested to take such actions as fixing the stress ring base,setting the special adjusting bolt clamping groove,and using the digital display dial indicator to accurately show the loading displacement.