【摘要】 用改进的WOL型试样研究了Cr-Mo-V系高强度钢在3.5%NaCl水溶液中的应力腐蚀断裂行为,并与常用的42CrMo钢进行了对比。结果表明,回火温度对实验钢的应力腐蚀开裂行为有显著影响。当回火温度较低时,Cr-Mo-V钢的KISCC较低,且随回火温度的升高缓慢提高,断裂方式主要为沿晶断裂;当回火温度超过约873K后,KISCC显著提高,断口中穿晶断裂所占的比例明显增加,断裂方式逐渐转变为穿晶型断裂为主。在相同的强度水平下,Cr-Mo-V钢的KISCC高于42CrMo钢,且在低强度水平下二者差别较大。对42CrMo钢,KISCC随屈服强度升高呈指数下降。但对Cr-Mo-V钢,则并非如此,即在强度保持不变(Rp0.2=1410~1440MPa)的条件下,KISCC随回火温度升高而明显提高。Cr-Mo-V钢和42CrMo钢的KISCC均随回火温度的升高呈指数关系增加。更多还原

【Abstract】 The stress corrosion cracking (SCC) behavior of secondary-hardening Cr-Mo-V high strength steel and 42CrMo steel for comparison in 3.5 pct NaCl aqueous solution were investigated by using bolt-loaded modified WOL type specimens. Experimental results show that the value of threshold stress intensity factor K_ ISCC of Cr-Mo-V steel is rather low and increases slowly with the rise of tempering temperature when tempered at lower temperature and the fracture mode is mainly intergranular fracture. When the tempering temperature is higher than 873K, the fracture mode changes from intergranular fracture to transgranular dominant fracture which causing a sharp increase of K_ ISCC . At same strength levels after tempering at different temperatures,K_ ISCC of Cr-Mo-V steel is higher than that of 42CrMo steel and this difference become significant at lower strength levels. The K_ ISCC of 42CrMo steel decreases exponentially with the increase of yield strength, however, this is not the case for Cr-Mo-V steel, that is to say, K_ ISCC increases significantly with increasing tempering temperature at same yield strength level(R_ p0.2 =1410～1440MPa). The K_ ISCC of both steels increases exponentially with the increase of tempering temperature. It is concluded that tempering temperature rather than strength has a significant effect on stress corrosion cracking behavior for the Cr-Mo-V high strength steel.更多还原