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完成了1Cr18Ni9Ti不锈钢管道对接焊接头母材、热影响区和焊缝金属三区域的局部微观结构、硬度和单调机械性能的详细试验研究。揭示了三区域存在明显差异 ,尤其是焊缝金属区的局部微观组织结构不均匀性和局部硬度、机械性能的分散性最大。说明了在结构分析中有必要考虑这种差异 ,并引入可靠性方法。此外 ,还揭示了由奥氏体基体 富δ铁素体带状结构组成的柱状晶是焊缝金属的特征微观结构 ,相邻富δ铁素体带的距离(40μm)恰好是该区域低周疲劳短裂纹行为中微观结构短裂纹(MSC)阶段和物理短裂纹(PSC)阶段的分界点。这说明其微观结构特征控制着疲劳损伤特点
The detailed experimental study on the local microstructure, hardness and monotonous mechanical properties of 1Cr18Ni9Ti stainless steel butt welded joint base metal, heat-affected zone and weld metal was completed. It reveals that there are obvious differences among the three regions, especially the local microstructure and inhomogeneity of the weld metal zone, as well as the local hardness. The dispersion of the mechanical properties is the largest. It shows that it is necessary to consider this difference in the structural analysis and introduce the reliability method. In addition, it is also revealed that the columnar grains composed of the δ-rich ferrite ribbon structure of the austenite matrix are the characteristic microstructures of the weld metal. The distance (40μm) between adjacent δ-rich ferrite bands is exactly the lowest Fracture Point of Microstructural Short Crack (MSC) Stage and Physical Short Crack (PSC) Stage in Fatigue Short Crack Behavior. This shows that the microstructural features control the characteristics of fatigue damage