Inconel718合金件裂纹产生原因分析

对Inconel718合金件在使用过程中裂纹产生的原因进行分析。结果表明：合金件在服役过程中主要受冷热应力与O、S元素的影响，过渡区域的棱边为应力集中区域，在热应力作用下为最容易破坏的位置。合金在服役过程中O和S扩散进基体，产生了氧化及硫化作用，使基体产生了氧化物和硫化物产物的的U型凹坑，加剧了应力集中区域的缺口敏感性，从而在冷热应力的作用下产生裂纹。裂纹的产生更易于O、S等有害元素向基体扩散，在应力作用下促使裂纹进一步扩展。在腐蚀、动态应力开裂、再腐蚀、冷热应力的作用下裂纹进一步扩展，是导致合金件失效的原因。

Analysis of Crack Generation Reason of Inconel 718 Alloy

In this work, the reason of crack generation of Inconel 718 alloy was analyzed by means of SEM , EDS and metallographic. The results show that Inconel 718 alloy is mainly affected by the hot and cold stress and detrimental gas elements. It tends to be damaged under the hot stress effect at the edge stress concentration position of transition zone. The pit of U type is generated on the alloy matrix because of the corrosion of oxygen and sulfur elements. The crack is generated at the root position of U type pit under the effect of hot stress. Crack generation makes the detrimental of oxygen and sulfur elements to easily diffuse into the matrix and erode. Then the crack is easy to expand under the effect of hot stress. The process of corrosion, crack generation under the stress, then corrosion, crack expand under the condition of cold and hot stress effect is the reason of Inconel 718 alloy failure.