【摘要】 测试了300M钢母材及电子束焊接接头高周疲劳性能,并结合断口宏/微观形貌分析了其高周疲劳断裂机制。结果表明:焊接接头高周疲劳性能低于母材的疲劳性能。母材试样表面微观缺陷以及硬脆的非金属夹杂Ti(C,N)粒子是诱导其疲劳微裂纹形成的两大因素。通过对电子来焊接接头高周疲劳断裂机制的分析认为:一方面,焊缝柱状晶结合强度低;另一方面,焊缝柱状晶粗大,晶面平直,且分布方向不一,在外加载荷作用下应变不协调,使沿最大切应力方向分布的柱状晶在低循环次数下即沿晶界开裂形成疲劳微裂纹。更多还原

【Abstract】 The high cycle fatigue properties of 300M steel electron beam welded joints were tested and the high cycle fatigue failure mechanism was analyzed combined with macro / micro morphology of the fracture. Results indicate that the fatigue strength of welded joints is lower than that of the parent metal. The micro defects at the specimen surface and the non- metallic inclusions of Ti( C,N) particles are the two factors which induced the fatigue crack initiation of 300M steel. The reason for why the fatigue strength of 300M steel electron beam welded joints is lower than that of parent metal can be attributed to the following two points. On one hand,the cohesion strength of the columnar grain boundary is low; on the other hand,columnar grains in weld metal is long,grain surface is very flat and the direction of its distribution is different. Under the fatigue loading,the columnar grain boundary which distribute along the maximum shear stress direction facilitate the formation of fatigue crack.更多还原