2.25Cr-1Mo-0.25V钢焊缝冲击性能和显微组织分析

Impact properties and microstructure of welded joints of 2.25Cr-1Mo-0.25V

进行了2.25Cr-1Mo-0.25V钢的焊条电弧焊试验,测定其焊缝的成分和冲击吸收功,进行了金相及启裂源观察,对冲击吸收功较低的样品进行脱脆处理.结果表明,冲击吸收功较低的焊缝的Mn,Si,Mo及其杂质元素含量相对较高,Mn,Si,Mo等元素促进杂质元素在晶界上的偏聚,致使晶界性能变坏,断口以沿晶断裂为主,冲击吸收功降低,脱脆处理后,冲击韧性恢复说明焊缝存在高温回火脆性,导致高温回火脆性是由于杂质元素在晶界上的偏聚,因此研制焊条时要严格控制Mn,Si,Mo和杂质元素的含量.

The steel of 2.25Cr-1Mo-0.25V was welded by manual arc welding,the composition of weld seam and its impact energy were tested,and the microstructure of welded joints and the initiated cleavage crack were analyzed and investigated.the weld samples with lower impact energy were treated to decrease the embrittlement.The research results show that weld seam with lower impact energy has more content of Mn,Si,Mo and other impurity elements.The elements such as Mn,Si,and Mo accelerate impurity elements segregated at grain boundaries.The impurity segregation on grain boundary decreases the properties of grain boundaries and the specimen fails as the intergranular fracture,so the impact energy value decreases.After the reduction of embrittlement treatment,the impact toughness will be recovered,and weld seam has high temperature temper brittleness.The reason of temper brittleness is that the content of impurity elements segregation on grain boundary.Based on the above-mentioned results,so the welding electrode for 2.25Cr-1Mo-0.25V steel was developed,the content of Mn,Si,Mo and impurity were strictly controlled.