镀锌Q&P980钢电阻点焊接头液态金属脆裂纹的形态及分布
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摘要
当某些固态金属或合金与特定的液态金属或合金直接接触时,在拉伸应力的作用下会出现强度与延伸率下降,以致提前失效的现象,这种现象被称为液态金属脆化.铁与液态锌接触时会出现液态金属脆化.对新一代高强热镀锌Q&P980钢板进行电阻点焊试验之后,在焊接接头表面发现了裂纹,裂纹内充满了锌金属,认为该裂纹的出现是由于点焊过程中镀锌层熔化,在应力的作用下使钢出现了液态金属脆化现象.液态金属脆化裂纹主要分布在电极压痕区的台阶及外周,且具有不同的深度及形态.
When some solid metals or alloys are to directly contact with specific liquid metals or alloys in tensile stress, their strength and ductility will drop and early fracture will occur, such a phenomenon is known as liquid metal embrittlement(LME). Iron can be embrittled by liquid zinc. After carrying out resistance spot welding experiment on the galvanized high strength Q&P980 steel plates, cracks were detected on the surface of joint, those cracks were found to be filled with zinc, thus it could be assumed that the cracks were caused by LME phenomenon, as zinc coating was melted and stress existed during welding process. LME cracks mainly distribute on the step and periphery of the indentation, and they showed different depth and forms.
When some solid metals or alloys are to directly contact with specific liquid metals or alloys in tensile stress, their strength and ductility will drop and early fracture will occur, such a phenomenon is known as liquid metal embrittlement(LME). Iron can be embrittled by liquid zinc. After carrying out resistance spot welding experiment on the galvanized high strength Q&P980 steel plates, cracks were detected on the surface of joint, those cracks were found to be filled with zinc, thus it could be assumed that the cracks were caused by LME phenomenon, as zinc coating was melted and stress existed during welding process. LME cracks mainly distribute on the step and periphery of the indentation, and they showed different depth and forms.
引文
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[2] KIM Y G,KIM I J,KIM J S,et al.Evaluation of surface crack in resistance spot welds of Zn-coated steel[J].Materials Transactions,2014,55(1):171-175.
[3] ASHIRI R,HAQUE M A,JI C W,et al.Supercri-tical area and critical nugget diameter for liquid metal embrittlement of Zn-coated twining induced plasticity steels[J].Scripta Materialia,2015,109:6-10.
[4] ASHIRI R,SHAMANIAN M,SALIMIJAZI H R,et al.Liquid metal embrittlement-free welds of Zn-coated twinning in-duced plasticity steels[J].Scripta Materialia,2016,114:41-45.
[5] 刁可山,蒋浩民,陈新平.基于成形特性的宝钢 QP980 试验研究及典型应用[J].锻压技术,2012,37(6):113-115.DIAO Keshan,JIANG Haomin,CHEN Xinping.Research and typical application of QP980 steel produced by BaoSteel based on formability[J].Forging & Stamping Technology,2012,37(6):113-115.
[6] FERNANDES P J L,JONES D R H.Mechanisms of liquid metal induced embrittlement[J].International Materials Reviews,1997,42(6):251-261.