板式换热器失效原因分析

Failure analysis of plate heat exchanger

换板式热器安装使用一个月即发生泄漏故障,解剖拆解换热器后发现,泄漏层位于换热器板壳内的传热不锈钢薄片钎焊热影响区。采用断口分析、表面宏观和微观形态分析、能谱成分分析、金相组织分析、维氏显微硬度测试等方法综合检测失效部位,发现失效性质为不锈钢应力腐蚀为,主要原因为钎焊工艺不当造成不锈钢基材晶界弱化,弱化晶界的不锈钢薄片无法承受设定工作要求而发生应力腐蚀开裂,导致换热板泄漏失效。

The plate heat exchanger was installed and used for a month before leaking failure.After dismantling the heat exchanger,it was found that the leakage layer was located in the heat-affected zone of the heat transfer stainless steel sheet brazing in the heat exchanger plate shell.Fracture analysis,surface macro and micro morphology analysis,energy spectrum component analysis,metallographic structure analysis,Vickers microhardness test and other methods are used to comprehensively detect the failure location,and it is found that the failure property is stainless steel stress corrosion,mainly due to improper brazing process As a result,the grain boundary of the stainless steel substrate is weakened,and the stainless steel sheet that weakens the grain boundary cannot withstand the set working requirements,and stress corrosion cracking occurs,resulting in the leakage of the heat exchange plate.