Abstract: Dissolution and precipitation of carbides in 3Cr17NiMo corrosion-resistant plastic mold steel were studied by means of JMatPro simulation calculation software and experimental research. The experimental results show that when austenitized at 1140 ℃, the 3Cr17NiMo steel undergoes isothermal annealing within the range of 740-1040 ℃, the carbides first precipitate at austenite grain boundaries in the form of fine rods or needles, and gradually grow into obvious network structure as the temperature decreases, without any phenomenon of spheroidization precipitation. Once network carbides are formed in the steel, they are extremely difficult to dissolve and eliminate. When the solution temperature is 1100 ℃, the carbides distributed in needle or rod shape are significantly reduced. With the extension of solution time, the austenite grain gradually tends to be equiaxed grain distribution, and the grain begins to coarsen. When the solution time is more than 10 h, due to the phenomenon of recrystallization, the grains are refined instead. After double solution treatment at 1100 ℃ for 20-30 h and 1060 ℃ for 3 h, the morphology of network carbides in the 3Cr17NiMo steel can be effectively improved, and good microstructure with a uniform structure and refined grains is obtained.

Key words: plastic mold steel, carbide, solution, precipitation, spheroidization