Thermal fatigue damage and residual mechanical properties of W-Cu/Ag-Cu/1Cr18Ni9 brazed joint

Highlights: • Thermal fatigue property of W-Cu/Ag-Cu/1Cr18Ni9 steel brazed joint were investigated. • With the increment of fatigue cycles, fatigue damage became increasingly serious. • Fracture changed from ductile to mixed ductile-brittle model after fatigue cycles. Thermal fatigue properties of W-Cu/1Cr18Ni9 steel brazed joint with Ag-Cu filler metal has been studied in this paper. With the increment of fatigue cycles, fatigue damage of the brazed joint became increasingly serious. There were micro holes and cracks appeared on the interface between brazing seam and base metals, and bending strength decreased from 690 MPa of the original joint to 380 MPa after 200 fatigue cycles. Fracture characteristic of W-Cu/Ag-Cu/1Cr18Ni9 joint changed from ductile fracture of the original joint to mixed ductile-brittle fracture after 200 fatigue cycles under external bending load and internal fatigue damage. The ductile fracture located on the Ag-based solid solution of brazing seam, and the brittle fracture occurred on the W-Cu composite.