δ-铁素体对P91耐热钢接头冲击性能的影响

Influence of delta-ferrite content on impact toughness of P91 heat-resistant steel joint

采用光学显微镜、显微硬度计和扫描电镜等分析方法研究了P91钢接头组织中δ-铁素体形态、分布和含量对其冲击韧性的影响。结果表明,随着热输入的增加δ-铁素体含量先增多随后趋于稳定;δ-铁素体分布不均匀,呈多边形分布于热影响区,以及少量呈条状分布于焊缝;δ-铁素体含量对冲击韧性有显著影响,随着δ-铁素体含量增多,接头的冲击韧性下降;冲击断口形貌从韧/脆混合断裂转变为脆性断裂。

The influence of delta-ferrite morphology,distribution and content on microhardness and impact toughness of P91 steel joint was studied by means of metallographic microscope,microhardness test and scanning electron microscopy. The results indicate that with the heat input increasing,the volume fraction of delta-ferrite increases and then tends to be constant,delta-ferrite distributes non-uniformly,polygonal morphology is largely aggregated in the heat effect zone（HAZ） and trace strip morphology presents at the weld zone（WZ）.However,the content of delta-ferrite has remarkable effect on impact toughness of the joint,and the impact toughness decreases with the amount of delta-ferrite increasing. The impact fracture morphology transforms from ductile/brittle mixing fracture to brittle fracture.