Characteristics of microstructure and stresses and their effects on interfacial fracture behavior for laser-deposited maraging steel

•Compressive stress existed in clad layer, and tensile in HAZ with a depth of 4 mm.•Stress profile resulted from interaction between thermal shrinkage and martensitic expansion.•Fracture morphology presents recognizable boundaries along laser scanning direction.•Solidification voids and steep stress gradient facilitated interfacial crack propagation.

Laser cladding is one of the most attractive ways to repair or remanufacture high-added-value engineering components. The present paper describes the effect of microstructure and residual stresses on the interfacial fracture behavior of laser-deposited maraging steel. The multi-layer overlapped cladding material was deposited on maraging steel substrates using laser hot-wire deposition. Residual stress profile was measured by X-ray diffraction. Temperature evolution and the induced phase transformation during the process were investigated to reveal the generation mechanism of residual stresses. A novel testing method was developed to analyze the interfacial fracture behavior and evaluate the bonding strength with specially designed T-shaped samples. The compressive stresses derived from martensitic expansion was presented in the clad layer, and tensile stresses in the heat affected zone up to a depth of 4 mm, which was caused by thermal shrinkage. Both the solidification micro-voids and steep stress gradient appearing in the interface contributed to the propagation of interfacial crack that will critically affect the mechanical properties of laser deposited material.

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