1000 MPa级高强钢埋弧焊熔敷金属组织及性能

Microstructure and properties of submerged arc weld metal of 1000 MPa grade high strength steel

针对水电用1000 MPa级高强钢设计了一种埋弧焊用焊丝、焊剂。借助JMat Pro软件对熔敷金属的组织和力学性能进行模拟,并通过拉伸试验、冲击试验、OM,SEM,EDS等手段对其进行评价。研究了熔敷金属成分和焊接热输入对熔敷金属组织及力学性能的影响。试验结果表明,研制的焊材焊接工艺性优良,通过控制合金元素含量使熔敷金属力学性能远高于标准值;重点分析了Cr含量对熔敷金属组织和力学性能的影响,熔敷金属中少量的Cr元素会提高针状铁素体含量,Cr元素含量较高时,会增加贝氏体含量,使熔敷金属强度不断提高,冲击韧性先提高后降低;随着焊接热输入的升高,熔敷金属中针状铁素体含量不断减少,先共析铁素体含量提高,组织粗化,熔敷金属强韧性不断降低。

Welding wire and welding flux were designed for submerged arc welding of 1000 MPa grade high strength steel used in hydropower.JMat Pro software was used to simulate microstructure and mechanical properties of weld metal.Microstructure and mechanical properties of weld metal were evaluated by means of tensile test,impact test,OM,SEM and EDS.Effects of weld metal composition and welding heat input on microstructure and mechanical properties of weld metal were analyzed.The test results showed that the developed welding consumables had excellent welding process.Mechanical properties of weld metal were higher than standard values by controlling content of alloying elements.Effects of Cr content on microstructure and mechanical properties of weld metal were particularly analyzed.A small amount of Cr in weld metal would increase needle ferrite content,while a higher Cr content would increase bainite content,which resulted in increasing strength and first increasing and then decreasing impact toughness of weld metal.As welding heat input increased,acicular ferrite content of weld metal decreased and pre-eutectic ferrite content increased,microstructure was coarsened,and strength and toughness of weld metal decreased.