Super-Ni/NiCr叠层材料Ni-Cr-Si-B高温钎焊接头的组织特征及抗剪强度

Microstructure and shear strength of high-temperature brazed joint of Super-Ni/NiCr laminated composite using Ni-Cr-Si-B filler metal

摘要: 采用Ni-Cr-Si-B高温钎料对Super-Ni/NiCr叠层复合材料和Cr18-Ni8不锈钢进行真空钎焊,并分析钎焊接头的显微组织及物相组成、显微硬度、抗剪强度及断口形貌.结果表明,钎缝主要由γ-Ni固溶体、Ni₃B、CrB和Ni₃Si组成;钎缝的显微硬度波动较大,γ-Ni基体显微硬度为450 MPa,Ni₃B的显微硬度最高650 MPa.钎焊温度升高至1120℃时,接头的抗剪强度最高可达158 MPa,NiCr基层钎缝区呈脆性断裂,出现撕裂韧窝.钎缝区与Super-Ni复层之间形成Ni₃B界面,Super-Ni复层钎缝区断裂于Ni₃B界面.

Abstract: Super-Ni/NiCr laminated composite and Cr18-Ni8 steel were brazed with Ni-Cr-Si-B high-temperature brazing filler metal. The microstructure, phase constitution, shear strength and fracture morphology were analyzed. The brazed region consisted of γ-Ni solid solution,Ni₃B,CrB and Ni₃Si. The microhardness fluctuated across the brazed region. The microhardness of γ-Ni substrate was 450 MPa and that of Ni₃B was 650 MPa. The shear strength of the joint increased to 158 MPa as the brazing temperature increased to 1 120℃. The fracture surface displayed brittle features with some shearing dimples. Ni₃B interface formed between the super-Ni and brazed region. The joint fractured through the Ni₃B interface.