Evaluating the effect of repair using direct laser metal deposition on the fracture resistance of the cracked 1.2714 tool steel component

Abstract

Abstract Hot work steel DIN1.2714 (56NiCrMoV7) has become a widely used material in making all kinds of industrial molds such as forging, punching, and coining due to its excellent machinability, moderate corrosion resistance, and relatively low cost. The cyclic performance of these molds will lead to the formation of surface cracks on the surface of these molds over time. Repairing these cracked parts is one of the most widely used topics in the industry, and in this research, the laser cladding method was used to repair the surface of these molds. Tensile fracture testing was performed according to ASTM E1820 guidelines on single-edge cracked specimens that were repaired by the DLMD process. In this study, the effect of laser cladding process parameters (laser power and percentage of reinforcing nanoparticles) as well as the effect of crack length on the remaining strength were investigated. In the following, the experimental displacement field obtained from the analysis of digital image correlation was used to create boundary conditions for a finite element post-processing model. The finite element model was calculated using a developed code and the fields of stress and strain as well as the J- integral parameter for coated and uncoated samples. The results show that by increasing the laser power from 150 W to 450 W and by increasing the percentage of nanoparticles of Sic from 0–5%, the failure load of the samples increases by 171% and 139%, respectively, and the J-integral parameter is reduced by 32% and 41% respectively. On the other hand, it was observed that by reducing the crack length from 25 mm to 3 mm, the failure load of the samples increased by 158% and 240%, respectively, and the J-integral parameter also decreased by 55% and 40% respectively.