焊接CGHAZ相变超塑性及对拉伸断裂性能的影响

藉助于Ｇｌｅｂｌｅ１５００热模拟试验机，采用模拟焊接热循环拘束位移的方法，测定了ＨＴ８０钢模拟ＣＧＨＡＺ的膨胀曲线和拘束应力曲线，研究了ＣＧＨＡＺ的相变超塑性现象，并试验获得了静拉伸强度与塑性．试验结果表明：（１）在模拟焊接ＣＧＨＡＺ中确是存在着相变超塑性，其变形量随着拘束位移的增大而增大；（２）相变超塑性具有使ＣＧＨＡＺ晶粒细化、降低强度和提高塑性的作用，这些都是以往难以实现的问题；（３）焊接过程的强拘束导致ＣＧＨＡＺ发生相变超塑性，不仅降低了ＣＧＨＡＺ的残余应力，而且改善了显微组织与力学性能

TRANSFORMATION SUPERPLASTICITY IN WELDING CGHAZ AND ITS EFFECTS ON TENSILE MECHANICAL PROPERTIES

Transformation superplasticity in welding CGHAZ (coarse grain heat affected zone) of HT 80 steel is studied by using simulated thermal cycle with restrained displacements by means of Gleeble 1 500 simulator. The static tensile strength and ductility of specimens from simulated welding CGHAZ are determined. Experimental results show that:(1)there does exist transformation superplasticity in the simulated welding CGHAZ and its values are increased with increasing restrained displacements; (2)the transformation superplasticity results in the drop in strength and the lift in ductility; (3)the transformation superplasticity makes both residual stress and grain size in the CGHAZ decreased so that microstructure and mechanical properties are improved.