焊接接头跨区试样断裂过程的研究

在系列温度下测定了两种焊接接头跨区(焊缝,热影响区,母材)试样的冲击韧性和COD,进行了断口的宏观与微观的观察分析。实验结果表明,非均质跨区试样的冲击韧性与COD之间不存在一般的相关关系。在本实验条件下,冲击韧性取各区韧性的平均值,而COD取各区韧性的最低值。从两韧性指标的物理意义、试样宏观断裂过程和微观断裂机制方面考察了实验现象产生的原因,发现跨区试样在延性裂纹扩展后高强区一侧对低强区一侧的解理存在屏蔽作用。

Analysis of the Fracture Processes of Welded Joints With Weld-HAZ-Base Metal Specimens

The V-Charpy imact toughness and the COD measurement are performed using two kinds of welded joint specimens,in which there are three zones: the weld,the heat affacted zone, and the base metal across the same notch or precrack front of the same specimens, at various temperatures. Macroscopic and microscopic observation and analysis of the fracture are, then, conducted. The results show that there are no general correlation between the impact toughness and the COD. The former takes the everage toughness value, whereas the COD is controlled by the lowest toughness value of the three zones in the specimen. The phenomenon occured during the experiments is discussed in the view of the physical meaning of the two toughnesses, the fracture processes, and the fracture micromechanisms. The shielding effect is found to be existing . It is found also that the cleavage from the high strength side to the low strength side is shielded as the ductile crack has developed in this kind of speimen .