A required finite element method（FEM） model applicable for narrow gap CMT and CMT＋P MIX welding was established based on the interactions between arc,base metal and filler metal.A novel method of simplifying wire f...
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A required finite element method（FEM） model applicable for narrow gap CMT and CMT＋P MIX welding was established based on the interactions between arc,base metal and filler metal.A novel method of simplifying wire feeding pulses and heat input pulses was supposed under the conduction of equivalent *** method together with composed double-ellipse heat sources was included in the *** model was employed in the investigation of thermal cycling and the identification of the softened zone of AA7A52 base ***-frequency behavior emerged in the form of low-cooling rate sects,which were not expected under experimental *** softened zone including the quenched zone and averaging zone of the base plate was much wider internal the base plate than that close to the *** reliability of the predictions in thermal cycling was supported by infrared imaging test results of the thermal cycle process.
研究了-60℃冷处理对42Cr Mo A钢表面盐浴渗氮与氧化复合(QPQ)处理层的影响。采用扫描电镜观察截面形貌,用纳米压入法测定了沿深度方向的硬度变化,用划痕法测定了涂层/基体的结合强度,用X射线衍射(XRD)测定涂层物相变化情况。结果发现:...
详细信息
研究了-60℃冷处理对42Cr Mo A钢表面盐浴渗氮与氧化复合(QPQ)处理层的影响。采用扫描电镜观察截面形貌,用纳米压入法测定了沿深度方向的硬度变化,用划痕法测定了涂层/基体的结合强度,用X射线衍射(XRD)测定涂层物相变化情况。结果发现:QPQ处理后42Cr Mo A钢表面生成疏松层、渗氮层和扩散区,疏松层由氧化层(~10μm)和氧-氮共混区(~5μm)组成。渗氮层(10~15μm)硬度>800 HV0.05,扩散区(0.3~0.4 mm)硬度从约500 HV0.05梯度降低到基体硬度(约325 HV0.05)。QPQ处理在42Cr Mo A钢表面生成的渗氮层与扩散区结合较好,结合强度(划痕法)约25 N。-60℃冷处理未对QPQ处理层的硬度以及渗氮层/扩散区的结合强度产生显著影响。但冷处理显著弱化疏松层与渗氮层的结合,导致疏松层在较大范围剥离。
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