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    L245M钢管环焊接头的氢脆敏感性

    Hydrogen Embrittlement Sensitivity of Girth Welded Joints of L245M Steel Pipe

    • 摘要: 分别采用E7018-1H4R焊条和某国产E5015焊条对L245M钢管进行环焊试验,在接头母材、热影响区和焊缝区域预制缺口,通过未充氢和预充氢状态下的慢应变速率缺口拉伸试验研究了接头不同区域的缺口拉伸性能,分析了氢脆敏感性,并观察拉伸断口形貌。结果表明:充氢未影响L245M钢母材的缺口抗拉强度,氢脆敏感指数仅为5.2%,母材具有较低的缺口敏感性和氢脆敏感性;E5015焊条焊接得到的焊缝和热影响区以及E7018-1H4R焊条焊接得到的焊缝和热影响区的氢脆敏感指数分别为47.5%,9.5%,9.1%,6.6%,除E5015焊条焊接得到的焊缝具有较高的氢脆敏感性外,其余均具有良好的抗氢脆能力;预充氢对E7018-1H4R焊条焊接得到的热影响区和焊缝断口形貌未产生明显影响,仍分别为韧窝形貌和韧脆混合断口形貌,预充氢使E5015焊条焊接得到的热影响区断口形貌由韧窝形貌变为韧脆混合断口形貌,焊缝韧脆混合断口形貌中脆性断口占比增大。

       

      Abstract: Girth welding tests were performed on L245M steel pipes by using E7018-1H4R electrodes and a domestic E5015 electrode, separetely. Notches were prefabricated in the base metal, heat-affected zone and weld of the joints. The notch tensile properties of different regions of the joints were investigated by slow strain rate notched tensile tests under uncharged and pre-charged hydrogen conditions. The hydrogen embrittlement sensitivity was analyzed, and the morphology of the notched tensile fracture was observed. The results show that pre-charging with hydrogen had no effects on the notched tensile strength of the L245M steel base metal. The hydrogen embrittlement sensitivity index of the base metal was only 5.2%, indicating low notched sensitivity and hydrogen embrittlement sensitivity. Under pre-charged hydrogen condition, the hydrogen embrittlement sensitivities of the weld and heat-affected zone obtained by welding with the E5015 electrode and those obtained by welding with the E7018-1H4R electrode were 47.5%, 9.5%, 9.1%, 6.6%, respectively. Except for the weld obtained by welding with the E5015 electrode, which exhibited high hydrogen embrittlement sensitivity, all other regions showed good resistance to hydrogen embrittlement. Pre-charging with hydrogen had no significant effect on the heat-affected zone and weld fracture morphology obtained by welding with the E7018-1H4R electrode, which remained as dimple morphology and mixed fracture morphology of toughness and brittleness, respectively. Pre-charging with hydrogen transformed the fracture morphology of the heat-affected zone obtained by welding with the E5015 electrode from dimple morphology to mixed fracture morphology of toughness and brittleness, and the proportion of brittle fracture in the mixed fracture morphology of toughness and brittleness in the weld increased.

       

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