Influence of cold sprayed Cr3C2-Ni coating on fracture characteristics of additively manufactured 15Cr-5Ni stainless steel

In this research the influence of heat treatment and a combination of heat treatment and a cold spray (CS) coating on tensile, fracture toughness, and fatigue characteristics of additively manufactured 15-5 precipitation hardenable stainless steel (15-5 PH SS) was studied. Test specimens of ASTM standard geometry were produced by direct metal laser sintering of 15-5 PH SS powder and subsequently heat treated. A thin layer of chrome-carbide nickel (Cr3C2-Ni) was deposited on the specimens using CS, which were then subjected to ASTM tensile, fracture toughness, and fatigue crack growth rate tests. In addition, to examine the influence of CS coating on the microscale properties and fracture morphology of heat treated 15-5 PH SS a series of test including, microstructure analysis, nanoindentation, and fractography were performed. CS deposition of Cr3C2-Ni on the additively manufactured 15-5 PH SS was found to have a beneficial influence on the uniaxial tensile strength and fracture toughness. Also, fatigue crack growth rate results indicated a notable enhancement in the near threshold, Paris, and fracture toughness. Improvements in the fracture characteristics were associated with the significant contribution of CS coating on grain size refinement and improvement of nanomechanical properties at and ahead of the crack tip. (C) 2018 Elsevier Ltd. All rights reserved.