Microstructure and Properties of Welding Joint of 8%Ni High Strength Steel
This paper analyzes the mechanism of unnormal phenomena that in the HAZ of 8% Ni high strength steel, the charpy V toughness at-50℃ in the coarse grain HAZ is higher than that of fine grain HAZ.The former fracture is induced by void growing until impingement-resulting coalescence in the CG-specimen and the latter fracture by forming shear sheets of the secondary voids to connect the neighboring primary voids before their impingement.This paper reveals that the critical event for cleavage fracture in this high strength steel and weld metals is the propagation of a bainite packet-sized crack across the packet boundary into contiguous packets and the bainitic packet sizes control the impact toughness.The high-angle misorientation boundaries detected in a bainite packet by EBSD form fine tear ridges on fracture surfaces.However, they are not the decisive factors controlling the cleavage fracture.The content of Ni is essential for improving the toughness.The extra large cleavage facets seriously deteriorate the toughness, which are formed on the interfaces of large columnar crystals growing in welding pools with high heat input.
980MPa 8 Ni high strength steel weld metal impact toughness fracture high-angle misorientation boundaries
R.Cao J.H.Chen Y.Peng
State Key Laboratory of Gansu Advanced Non-ferrous Metallic Materials and Key Laboratory of Non-ferr Central Iron Steel Research Institute,Beijing 100081,China
国际会议
2014 International Symposium on Structural Integrity,ISSI2014(2014国际结构完整性学术会议)
兰州
英文
123-135
2014-08-20（万方平台首次上网日期，不代表论文的发表时间）