Thermal fatigue life prediction method for die casting mold steel based on the cooling cycle

The die casting die is heated and cooled rapidly in the process of die casting, which is easy to produce thermal fatigue cracks, which will lead to fatigue fracture, damage, and ultimately failure. Thermal fatigue cracking is one of the most common failure mechanisms of die casting dies. In this paper, a thermal fatigue test method based on cyclic induction heating was proposed to evaluate the thermal cracking of actual die casting die steel. The 4CrMo4 die steel and standard H13 die steel produced by double vacuum smelting were used as research objects to study the influence of different thermal fatigue cycles on the thermal fatigue crack of two die steels, discuss the mechanism of thermal fatigue crack initiation and propagation, and compare and analyze the thermal fatigue life of two die steels.The macro model of 4CrMo4 die steel sample was simulated by numerical simulation method for thermal fatigue cycle and thermal crack growth, and the results were analyzed and compared with those of thermal fatigue test. Then used neper software to build a microscopic three-dimensional polycrystalline geometric model, loaded the thermal load in ABAQUS software, and correlated the results with the test data.By calculating the test cycle, a new fatigue life prediction method was proposed, which related the cooling cycle during the die-casting cycle and the thermal fatigue cracking cycle. A prediction criterion based on cooling cycle was proposed to predict and improve the thermal fatigue life of hot work die steels in die casting and other manufacturing industries.