Wear Resistance And Life Prediction Of Gradient Cladding Layer On H13 Steel

Hot-work die surface is subjected high-intensity contact and high-frequency alternating thermal load in the process of service,short life of the die seriously.Wear is the main failure mode of hot working die.The surface modification technology such as laser cladding is used to improve the wear resistance of the die,which can effectively prolong the service life,reduce the production cost and save resources.Therefore,it is of great significance for practical application of die structure optimization,improvement of die service life and daily maintenance to discuss the internal influencing factors of die surface cladding layer wear,grasp the wear law and establish prediction model of die life.In this paper,a laser cladding technique was used to prepare a gradient cladding layer with Ni/WC content of 15% and 30% on the surface of common hot working die material H13.The laser cladding process parameters of H13+Ni/WC composite powder were determined.The mechanical properties of the substrate and the cladding were tested and compared.The effects of various factors on the wear resistance of the substrate and the cladding layer were discussed,the wear resistance was compared,and the wear mechanism of the cladding was analyzed.Based on the experimental data,combined with numerical simulation and mathematical statistics,the theoretical service life of the die was predicted by GA-BP neural network.The surface of the obtained cladding layer is relatively flat.There are no defects such as cracks,voids and slag inclusion,no obvious boundary between the layers,and a fine metallurgical bond with the substrate inside.The micro-Vickers hardness of the cladding section has a clear gradient from the surface of the substrate to the cladding layer.The microVickers hardness of surface is close to 1100HV0.2,which is about 2.4 times that of the substrate(450 HV0.2).With the increase of temperature,the Vickers hardness of the surface of the substrate and the cladding layer decreased from 1510.35 HV10 and 1347.68 HV10,respectively,and the decrease of the cladding layer was larger than that of the substrate.At about 500 °C,the hardness of the two layers was equivalent.When the temperature is below 500 °C,the wear resistance of the cladding layer is better than that of the substrate,while the wear resistance of the cladding layer is slightly inferior to the substrate at 500 °C and above.The influence of load and temperature on the wear depth of matrix is highly significant,the rotational speed is generally significant,and the order of factors affecting is temperature,load and rotational speed.The influence of load,temperature and revolution on the wear depth of cladding layer is highly significant,and the order of main effect intensity is temperature,revolution and load.The maximum test error of the hightemperature wear model of the cladding layer and the matrix constructed by GA-BP neural network is about 0.16% and 0.18%,respectively.Based on the wear model,combined with the numerical simulation of the reverse-squeezing hot-formed H13 thin-walled tubular part,the single-formed nodes are calculated by numerical integration.The results show that the maximum wear depth of the cladding in the middle of the fillet is about 0.4?m,and the matrix is about 0.59?m at the beginning of the rounded corner in the axial direction.Under the assumption of a wear limit of 0.5 mm,the theoretical service life of before and after cladding is predicted to be 840 and 1250,respectively.