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用表面残余压应力试样,U型弯曲试样(用其压缩区)和WOL恒位移缺口压缩试样对1Cr18Ni9不锈钢在沸腾MgCl_2溶液中进行了压应力条件下的应力腐蚀试验。结果表明,三种试样分别经110h,73—100h以及262—324h后都观察到了由压应力所产生的应力腐蚀裂纹,并获得了具有岩层状特征的准解理脆性断口。这和拉应力腐蚀时获得的解理断口明显不同。压应力条件下应力腐蚀裂纹的孕育期比拉应力要高1—2个数量级,而且裂纹扩展缓慢,加上裂纹不能张开而难于辨认,故当试样中同时存在拉应力时将不会观察到压应力所产生的应力腐蚀裂纹。
The stress corrosion tests of 1Cr18Ni9 stainless steel under compressive stress in boiling MgCl 2 solution were carried out by compressive specimens with surface residual stress, U-shaped specimens (with its compression zone) and WOL specimens with constant displacement. The results show that the stress corrosion cracking caused by compressive stress is observed after 110h, 73-100h and 262-324h, respectively, and the quasi-cleavage brittle fracture with rock strata is obtained. This is clearly different from the cleavage fracture obtained when tensile stress is eroded. The stress corrosion cracking stress period is one to two orders of magnitude higher than the tensile stress, and the crack propagation is slow. Moreover, the crack can not be opened and is difficult to identify. Therefore, the sample will not be observed when there is tensile stress To compressive stress generated by stress corrosion cracking.