摘要
六角头螺栓安装1 a后出现断裂,对螺栓断口采用宏观检验,断口较平直,断面上存在放射状条纹。断口分析表明,晶粒间有二次裂纹,晶面上存在大量"鸡爪痕",部分区域微观形貌为准解理断口,并伴有少量韧窝。表面和心部显微硬度满足标准要求,断裂螺栓心部组织为回火索氏体,螺栓断口附近螺纹表面未发现増碳现象。断裂螺栓断口氢质量分数为3×10^(-6)。结果表明:螺栓为氢脆断裂,是由于选材不合理、基体残留氢含量偏高及螺栓硬度偏高造成的。
Macroscopic inspection was conducted to observe the fracture of hexagon head bolt which fractured after one year installation, the surface of fracture was straight and there were radial stripes on the cross section. Fracture analysis showed that there were second cracks among crystal grains, a large number of ＂chicken feet mark＂ could be observed on the crystal face, a part of the regional morphology were quasi cleavage fracture, and accompanied by a small number of dimples. The values of the surface and micro hardness met the requirements of the standard. The core microstructure of fracture bolt was tempered sorbite. The carbonization phenomenon were not found on thread surface near the bolt fracture. Hydrogen mass fraction of the bolt fracture was 3 ×10-6. The results showed that the fracture mechanism was the hydrogen embrittlement fracture. The reasons of fracture were due to the unreasonable selection of material, high residual hydrogen content and high hardness of bolt.
出处
《金属制品》
2016年第4期58-61,共4页
Metal Products
基金
中国电力工程顾问集团公司基金项目
编号:DG1-T06-2014
关键词
六角头螺栓
断裂分析
氢脆
金相组织
hexagon head bolt
fracture failure analysis
hydrogen embrittlement
microstructure
