Research On X100 Welding Heat Affected Zone And Mechanical Properties

In the process of welding pipeline steel, it is unavoidable to apply certain pressure in seam and HAZ. And it is found that the mechanical property of HAZ applied pressure is better than that without pressure. But there are few reports on the influence of pressure on the mechanical property of seam and HAZ. Therefore, it is necessary to study the influence law of pressure on the microstructure and property of seam and HAZ.Welding simulation software SYSWELD tells the temperature history in seam and HAZ and microstructure evolution. Based on the temperature changing process, the SHCCT curve of the seam and HAZ is built, to study the stress' influence law on transformation point. Studing studies the stress' influence on impacting energy based on the analysis of impact test;and the research results show that:1)First using the finite element drawing software Visual-mesh to build a 3D welding model, and then uses the computer simulation software SYSWELD to imitate the welding process, and obtains the temperature field, organization field and temperature history curve on different location under different heat cycles.2)Using thermal simulator Gleeble3500 to measure the SH-CCT curve of X100 pipeline steel with thermal dilation method under different stresses. Analyzing it combined with the drawn phase change kinetics curve, which gains the stress' influence law on transformation point,and then making an observe and hardness test on the transformation products,got the stress' influence law on organization and property transformation.3)For the thermal cycle samples of internal and external welding overlap region obtained with and without pressure, the hardness and impulse test should be carried out to achieve the influence law coping with the hardness and impact toughness. Through observation under OM and SEM, the influence laws coping with structural transformation and fracture appearance are revealed.