理化检验-物理分册2017，Vol.53Issue(10)：740-745,749,7.DOI:10.11973/lhjy-wl201710010
液氨储存罐304不锈钢法兰连接螺栓断裂失效分析
Failure Analysis on Fracture of 304 Stainless Steel Flange Connecting Bolts of a Liquid Ammonia Storage Tank
史宝良 1李岩 2张腾飞 1江克洪 1欧阳薇2
作者信息
- 1. 法焊科技(深圳)有限公司,深圳 518000
- 2. 浙江吉利控股集团 制造工程中心,慈溪 315300
- 折叠
摘要
Abstract
The 304 stainless steel flange connecting bolts of the pneumatic valve of the gas ammonia outlet above the liquid ammonia storage tank in a power plant fractured during service,the fracture failure reasons of the 304 stainless steel bolts were analyzed through the aspects of microstructure,fracture,hardness and tensile property by using metallographic microscope,scanning electron microscope,micro-hardness tester,tensile testing machine, etc.The results show that the failure mode of the bolts was stress corrosion cracking.The unqualified chemical compositions (high carbon content and low chromium content)of the bolts resulted in the decrease of corrosion resistance of the alloy and the increase of the tendency of intergranular stress corrosion.Because the bolts were exposed to the marine atmosphere near the coast which exhibited a higher concentration of Cl-,the surface of the bolts were easy to be corroded during the long time exposure,and the cracks rapidly expanded along the grain boundaries under the combined effect of the pre-tightening force,the tensile stress produced during the service of the pneumatic valve of the gas ammonia outlet and the Cl- until the occurrence of fracture.In addition,there were many casting defects in the bolts,which could significantly reduce the mechanical properties of the alloy and make the bolts fracture prematurely in the case of corrosion.关键词
304不锈钢/螺栓/断裂/应力腐蚀开裂/失效分析Key words
304 stainless steel/bolt/fracture/stress corrosion cracking/failure analysis分类
矿业与冶金引用本文复制引用
史宝良,李岩,张腾飞,江克洪,欧阳薇..液氨储存罐304不锈钢法兰连接螺栓断裂失效分析[J].理化检验-物理分册,2017,53(10):740-745,749,7.
