Through macro-morphology,chemical analysis,metallographic examination,hardness testing and scanning electron microscope observation,the properties and causes of cracks in welded joints of small-diameter thick-walled pipes of 12Cr1 MoVG under the condition of low temperature and no preheating were studied.The results showed that under the low ambient temperature,no preheating before welding,and high heat input of the welding line,the residual stress at the weld seam increased and the plastic deformation capacity weakened.Furthermore,the appearance of vacancies at the austenite grain boundaries resulted in transverse cracking of the weld root layer perpendicular to the weld direction.For small-diameter thick-walled 12Cr1MoVG steel pipes,cracking of the weld seam can be effectively avoided by preheating before welding,controlling the interlayer temperature,post-weld heat treatment,adjusting the welding parameters,and reducing the welding heat input.
关键词
12Cr1MoVG钢/小径厚壁管/焊前预热/焊接线能量/残余应力/塑性变形能力/横向裂纹
Key words
12Cr1MoVG steel/small-diameter thick-walled pipes/preheating before welding/welding line energy/residual stress/plastic deformation capacity/transverse crack
维普
万方数据