Abstract: According to the phenomena of 8 ~ 12 mm plate tensile fracture layering of low alloy high strength welded steel HG70C (/%: 0. 069 ~D. 077C, 0. 07 〜0. HSi, 1. 79 〜L83Mn, 0.011 〜0.012P, 0. 004 ~ 0. 005S, 0. 121 〜 0. 123Ti, 0. 046 - 0. 047 Nb), the morphology of fracture and area near layering are observed and analyzed by using optical and scanning electron microscope and energy spectrum analyser, and the statistical analysis of heating process parameters of bloom in real production is carried out. Results show that the layering of the steel plate tensile fracture has nothing to do with heating process for hot rolling, it is mainly related to center pearlite segregation band and large titanium carbo-nitride, and this precipitates with 2μm is found in casting bloom which are fatigue source lad to layering of tensile fracture.

摘要： 针对低合金高强焊接钢HG70C(/%:0.069～0.077C、0.07～0.11Si、1.79～1.83Mn、0.011～0.012P、0.004～0.005S、0.121～0.123Ti、0.046～0.047Nb)8～12 mm板拉伸试验后试样断口出现分层的现象,利用金相显微镜、扫描电镜和能谱仪对断口形貌及分层附近区域进行了观察和分析,并且统计分析了实际生产中加热参数。结果表明,该钢种分层与热轧工艺无关,主要与中心珠光体偏析带及偏析处大颗粒Ti的碳氮化物有关,并且在铸坯中发现已有2μm左右的该类析出物颗粒存在,它们成为疲劳源导致拉伸断口分层。

关键词: 低合金高强焊接钢HG70C, 拉伸断口, 分层, 碳氮化物