The microstructure and properties change of dies manufactured by bimetal-gradient-layer surfacing technology

摘要

The finite element model of a die manufactured by the bimetal-gradient-layer surfacing method was established based on ZG29MnMoNi casting steel. Then, simulation was conducted to analyze the temperature field of the die and its cycle features under working conditions. By comparing the microstructure and properties of cast-steel matrix of the die before and after producing 5761 parts on a 63MN hot die forging press, sensitive indexes that affect the service life of the surfacing die were determined. The results have shown that the microstructure of cast-steel matrix before and after service is both pearlites and ferrites. When it is closer to the welding line, the carbides precipitate out more obviously, the dendrites segregate less, and the microstructure tends to be more compact. The mechanical properties are decreased as a whole after service: the tensile strength, yield strength, reduction of area, and elongation are declined by 7, 17, 24, and 18 %, respectively. Meanwhile, microhardness and impact toughness have shown a decrease of 10 and 28.6 %, respectively. The working temperature has a strong relationship with microstructure and property changes. The performance of cast-steel matrix after service can still satisfy the operating requirements of the 63MN hot die forging press, which can be recycled in remanufacturing process.