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本文通过三种类型的COD 试样,较详细地研究了12Ni3CrMoV 钢焊接热影响区(HAZ)中晶粒度与组织梯度对韧性的影响。试验结果表明,韧带区组织均匀的粗晶区热模拟试样,当晶粒尺寸变化时,启裂韧性δi 值不变,但抗裂纹扩展的阻力却变化剧烈,晶粒尺寸小,实际断裂扩展路径增长,表现为扩展阻力上升,反之则下降。对于实际焊接试样,裂纹扩展阻力的大小还与裂纹尖端前缘HAZ 的组织梯度有极大关系,当出现良好的塑性变形区域时,可增大抗裂纹扩展阻力,因此,焊接接头中裂纹扩展的可能性与裂纹所处的位置及扩展方向有关。
In this paper, the effects of grain size and microstructure gradient on the toughness of 12Ni3CrMoV steel in heat-affected zone (HAZ) of welded steel were studied in detail by three types of COD samples. The experimental results show that the fracture toughness δi constant when the grain size changes, but the resistance to crack propagation changes sharply, the grain size is small, the actual fracture propagation Path growth, the performance of resistance to increase the expansion, on the contrary decline. For the actual welding specimen, the crack propagation resistance is also greatly related to the microstructure gradient of the HAZ at the tip of the crack tip. When a good plastic deformation zone is obtained, the crack propagation resistance can be increased. Therefore, the crack propagation in the welded joint The possibility of cracks in the location and direction of expansion related.