20G变径管接头裂纹分析与研究

Analysis and Research on Crack of 20G Variable-Diameter Pipe Joint

通过化学成分分析、金相分析、硬度测试对20G变径管接头在水压试验保压过程中的开裂进行了分析。分析结果表明:该变径管接头开裂主要是因为变径管在加热压模过程中处于失塑阶段时受热不均匀产生了三种热过程组织,大大降低了材料的塑性;另外在管接头两侧均有焊接筋板,使得在焊接过程中受二次应力的影响,造成变径管接头在水压试验时开裂失效。

Through chemical composition analysis,metallographic analysis,and hardness test,the cracking of 20G reducing pipe joints in the pressure holding process of hydraulic test was analyzed.The analysis results show that the cracking of the reducer pipe joint is mainly due to the uneven heating of the reducer pipe in the ductility dip stage during the heating and compression molding process,which produces three kinds of thermal process structures,which greatly reduces the plasticity of the material.In addition,there are welded ribs on both sides of the pipe joints,which are affected by the secondary stress during the welding process,causing the reduced diameter pipe joints to crack and fail during the hydraulic test.