Y12Cr18Ni9Cu奥氏体易切削钢的高温塑性变形行为

为了研究Y12Cr18Ni9Cu奥氏体易切削钢的高温力学性能，利用Gleeble-3500热模拟机对Y12Cr18Ni9Cu钢进行了不同温度的高温拉伸试验，并对断口形貌、抗拉强度以及断面收缩率进行了分析。结果表明，随着温度升高试验钢的高温抗拉强度逐渐降低，断面收缩率逐渐增加。试验钢的低温脆性区为800～900℃,未出现高温脆性区。低温脆性区的出现是由于材料在热变形过程中没有发生动态再结晶，并且由于硫化物与基体所能承受的变形能力不同，裂纹在硫化物与基体界面产生，最终导致脆性断裂。在1150～1250℃温度范围内，试验钢发生了动态再结晶并表现出良好的高温热塑性，Y12Cr18Ni9Cu奥氏体易切削钢的热加工温度应选择在1150～1250℃之间。

Elevated temperature plastic deformation behavior of Y12Cr18Ni9Cu austenitic free-cutting steel

In order to study the elevated temperature mechanical properties of the Y12Cr18Ni9Cu austenitic free-cutting steel, the tested steel was subjected to elevated temperature tensile test at different temperatures by Gleeble-3500 simulator, then the fracture morphology, tensile strength and percentage reduction of area were analyzed. The results show that the elevated temperature tensile strength of the tested steel gradually decreases, while the percentage reduction of area gradually increases with the increase of testing temperature. The low temperature brittle range of the tested steel is 800-900 ℃, and there is no high temperature brittle range. The emergence of low temperature brittle range is due to the fact that the material does not undergo dynamic recrystallization during hot deformation and the different deformation capacities of sulfide and matrix, so that cracks are generated at the interface between sulfide and matrix, eventually leading to brittle fracture. In the temperature range of 1150-1250 ℃, the tested steel undergoes dynamic recrystallization and exhibits excellent elevated temperature thermoplasticity. The optimum hot working temperature of the Y12Cr18Ni9Cu austenitic free-cutting steel should be selected at 1150-1250 ℃.