X80管线钢用气体保护焊丝的研制

为了满足X80管线钢焊接时的强度、冲击韧性等性能要求,设计了以Mn-Ni-Mo-Ti-B为合金系的焊丝。确定了X80管线钢用气体保护焊丝熔敷金属组织应以大量针状铁素体和少量粒状贝氏体的复合组织为主,同时明确了焊丝的化学成分。试验分析表明,所用焊丝熔敷金属强度、冲击韧性和硬度等均达到了要求值。焊缝熔敷金属显微组织也达到了设计目标,即获得了以针状铁素体为主,其间弥散析出少量粒状贝氏体的焊缝复合组织。同时利用扫描电镜对冲击断口形貌进行了分析,断口具有典型的韧窝。最后利用透射电镜探究了针状铁素体在夹杂物表面的形核机理。

Development of Gas-shielded Welding Wire for X80 Pipeline Steel

In order to satisfy requirements during X80 pipeline steel welding,such as strength,impact toughness and other properties,the welding wire with Mn-Ni-Mo-Ti-B alloy system was designed.Furthermore,the deposited metal structure of gas-shielded welding wire based on composite structure for X80 pipeline steel was determined,containing plenty of acicular ferrite and a few granular bainite,at the same time,the chemical composition of welding wire was determined.Through test analysis,the deposited metal strength,impact toughness and hardness values of welding wire all reached the required value,and the microstructure of weld deposited metal also reached the designed goal,which was composed by a large number of acicular ferrite and a few granular bainite.At the same time,impact fracture profile was analyzed by scanning electron microscope,the fracture possessed typical dimple.Finally,the nucleation mechanism of the acicular ferrite in surface of the inclusions was explored by the transmission electron microscope.