奥氏体不锈钢大拉杆补偿器失效分析与预防

Analysis and Prevention Measures of Stainless Steel Compensator Failure

通过宏观检查、金相显微观察、电子扫描显微镜观察、X射线能谱仪检测等手段,对送检的DN350大拉杆补偿器进行失效分析。结果表明,其失效模式主要为应力腐蚀开裂,开裂位置处于补偿器的316L奥氏体不锈钢波纹管部分,裂纹呈分叉状,开裂的断面呈沿晶断裂和撕裂韧窝的组合形貌特征,裂纹周围的泥纹状腐蚀产物中含有外来腐蚀介质氯元素。进一步揭示腐蚀、应力腐蚀、疲劳开裂等失效模式的特征和机理,对不锈钢补偿器几种典型失效模式进行归纳,并从设计、制造、安装、试压和服役使用环节有针对性地提出失效预防措施和建议。

A failure analysis was carried out for a submitted compensator by means of macroscopic and microscopic examinations, scanning electron microscope inspection and energy dispersive x-ray. The mainly failure mode was the stress corrosion cracking. The cracks were at 316L austenite stainless steel corrugated tubes of the compensator. Fork-shaped cracks produced the fracture surface of intergranular fractography and tear dimples morphology. The external corrosive medium containing chlorine was tested in the mud-shaped corrosion products around the cracks. The characteristics were further revealed through the mechanisms of corrosion, stress corrosion, fatigue cracking failure mode. The failure modes of several typical stainless steel compensators are summarized. In the aspect of design, manufacture, installation, pressure test and service use, this paper puts forward the failure prevention measures and suggestions.