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高温液化裂缝在焊接热循环峰值温度的重热作用下,母材近缝区金属或多层焊缝的层间金属中,由于晶间层的重新熔化所导致沿原始奥氏体晶界产生的裂缝,称为液化裂缝(图16)。母材近缝区金属与多层焊缝中焊道下的层间金属,在热循环作用下被快速加热到接近熔点的高温,而后快速冷却。从力学因素上说,陡变的温度梯度,快速的热应变,为高温下的脆弱部分——晶间层发生开裂行为提供条件。从冶金因素分析,则是原始奥氏体晶界低熔组
High Temperature Liquefaction Cracks In the reheating of the peak temperature of the welding thermal cycle, the intermetallics in the near-seam metal or multi-layer weld seam of the base material are produced along the original austenite grain boundaries due to remelting of intergranular layers Cracks, called liquefied fractures (Figure 16). Near the seam area of the base metal, the intermetallic metal under the weld bead in the metal and the multi-layer weld is rapidly heated to a high temperature close to the melting point by thermal cycling and then rapidly cooled. In terms of mechanics, the steep temperature gradient and rapid thermal strain provide conditions for the cracking of the intergranular layer, which is the fragile part at high temperature. From the metallurgical analysis, it is the original austenite grain boundary low melting group