氢对套管钻井钢Ⅰ/Ⅲ复合型断裂韧性的影响

Influence of hydrogen on mixed-modeⅠ/Ⅲ fracture toughness of casing-drilling steels

利用SEM、疲劳实验机等研究了氢对套管钻井钢Ⅰ/Ⅲ复合型断裂韧性的影响。结果表明:充氢均使得Ⅰ型J积分JⅠ和Ⅲ型J积分JⅢ之间比例系数减小,即随着Ⅲ型载荷分量的增加,JⅠ降低量相同,充氢试样JⅢ增加更少,从而导致总J积分JT降低更多。充氢使得3种组织套管钻井钢纯Ⅰ型断裂韧性显著降低;通过外延法推测出,氢也使得纯Ⅲ型断裂韧性降低,当裂纹倾角为45°时,氢使得回火马氏体钢的Ⅲ型断裂韧性降低最显著。对于不同组织钢来说,回火马氏体钢对氢最敏感,铁素体-贝氏体-马氏体钢次之,珠光体-铁素体钢抗氢影响能力最强。相比未充氢试样,预充氢试样断口台阶表面显著更平整,这与充氢试样导致套管钻井钢具有更低的断裂韧性是一致的。

The effect of hydrogen on the mixed-mode Ⅰ /Ⅲ fracture toughness of casing-drilling steels was investigated by means of fatigue testers and SEM. The results show that hydrogen significantly brings down the ratio coefficient between the mode Ⅰ fracture toughness J Ⅰ and the mode Ⅲ fracture toughness J Ⅲ . This means, with increase of mode Ⅲ load, that the increase of J Ⅱ under the hydrogen pre-charging is less under the same decrease of J Ⅰ , so JT decreases. The decreases of three different microstructure casing-drilling steels J Ⅰ are remarkable. The inclusion can be obtained by extrapolation-extension method that JⅢ can be brought down by means of the hydrogen pre-charging, when the crack angle is 45°, that the decrease of tempered martensite steel（TM） steel J Ⅲ is the most remarkable. For the different microstructure steels, TM steel is the most sensitive to hydrogen, ferrite-bainite-martensite steel is in the middle, pearlite-ferrite steel is better for resisting hydrogen effect. Compared with uncharged hydrogen, the fracture surface of precharged hydrogen sample is remarkably flatter, which is consistent with a fact that its fracture toughness is the lowest.