Microstructure transform behavior of large heat input weld metals with rare earth Ce

• 1、Material Science and Engineering College of Huazhong Unversity of Science and Technology, WuHan 43007
• 2、Material Science and Engineering College of Huazhong Unversity of Science and Technology, Wuhan 43007, China

Abstract：In this paper，the microstructure transform behavior of the large heat input weld metals with rare earth Ce was studied. Weld thermal cycle curves of double-wire submerged arc welding were measured. The weld metal by double-wire multi-pass submerged arc welding has one time thermal cycle CGHAZ and two times thermal cycle IRCGHAZ. The microstructures of the large heat input weld metals are acicular ferrite that Ce oxide sulphide particles had induced nucleation and proeutectoid ferrite. The microstructures of CGHAZ and IRCGHAZ are acicular ferrite, sympathetic acicular ferrite（SAF）, proeutectoid ferrite and grain bainite. The first acicular ferrite with high density dislocation can induce SAF nucleation. The place that the acicular ferrite had induced SAF nucleation has transfixion curve. The grain bainite nucleated in the austenitic zone with high carbon content close to acicular ferrite and SAF. The microstructures of the large heat input weld metals with rare earth Ce has ability to grain self-refinement, which makes it high notch toughness values at low temperature.

Keywords： Microstructure Transform Large Heat Input Weld Metal Acicular Ferrite Sympathetic Acicular Ferrite Rare Earth Ce