材料期刊网

通过不同强度等级的34CrNi3Mo钢在80℃,30％NaOH水溶液中开路电位(-1050mv)及-1400mv(SCE)恒电位阴极极化条件下K_(ISCC)的测定,探讨强度对低合金钢SCC敏感性的影响。试验结果表明:在开路电位的条件下,SCC为塑性变形控制的活性通道溶解(SGAPC)型,K_(ISCC)随着σ_s的升高而升高;而在-1400mv(SCE)恒电位阴极极化条件下,SCC为氢脆(HE)型,K_(ISCC)则随着σ_s的升高而急剧下降。说明强度对不同机理的SCC有着不同的影响.对HE型SCC,降低强度可有效地降低钢的SCC敏感性,而对于SGAPC型SCC,降低强度反而增加了钢对SCC的敏感性。因此,过去大量从高强度钢所得到的强度对SCC敏感性的影响规律并不适用于SGAPC型的SCC。

The stress corrosion cracking (SCC) susceptibility of steel 34CrNi3Mo with different yield strength grades in 30% NaOH aqueous solution at 80℃ has been examined by the measurement of their K_(ISCC) either at open circuit potential (-1050mV) or cathodically polarized at-1400mV (SCE). It is shown that the SCC under the open circuit potential condition is of a strain generated active path corrosion (SGAPC) type, and under the cathodically polarized condition is of a hydrogen embrittlement (HE) type. With the increasing of the yield strength of the steel, the K_(ISCC) is increased under the open circuit condition, and sharply decreased under the cathodically polarized condition. For HE type, the reducing the strength of steel may effectively decrease the SCC susceptibility; while, for SGAPC type, it may increase the SCC susceptibility. Thus, the usual understanding of the effect of the strength on SCC susceptibility arrived from the tests of high strength steels in aqueous solution seems not to be suitable to those SCC of SGAPC type.