Abstract: High chromium alloy 3J40 was subjected to solution treatment at different temperatures (ranging from 1020 ℃ to 1200 ℃ with a holding time of 1 h) and aging treatment (at 700 ℃ and 800 ℃ with a holding time of 24 h). Effect of solution and aging processes on microstructure and properties of the 3J40 alloy was studied by using optical microscope, scanning electron microscope, universal tensile testing machine, and hardness tester. The results show that a large number of granular α-Cr phases are distributed in the matrix of the 3J40 alloy. With the increase of the solution temperature, the grains gradually become coarser, and the granular α-Cr phases gradually dissolve back into the matrix. When the solution temperature is 1200 ℃, all the α-Cr phases are dissolved. After aging at different temperatures, the supersaturated Cr element in the matrix of the 3J40 alloy precipitates again in the form of strip-shaped dendrites or lamellar structures. Meanwhile, as the precipitation amount of the lamellar α-Cr phase increases, the tensile strength and hardness of the alloy at room temperature are significantly improved, but the plasticity is significantly reduced.

Key words: 3J40 alloy, α-Cr phase, solution and aging treatment, microstructure, properties