Microstructure and properties of welding joint of 8%Ni high strength steel
This paper analyzes the mechanism of unmoral 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.It is caused of different fracture.The former fracture is induced by void growing until impingement-resulting coalescence in the CG-specimen,and the latter fracture is caused 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 packetsized 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 effects of Ni content are essential factors 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 and Steel Research Institute,Beijing 100081,China
国际会议
北京
英文
1-10
2013-06-16（万方平台首次上网日期，不代表论文的发表时间）