铜元素对304L不锈钢热加工性能的影响

Effects of Element Cu on Hot Workability of 304L Stainless Steel

摘要:

采用Gleeble-3800热模拟试验机对含铜304L不锈钢进行热压缩实验，变形温度为900~1150 ℃，应变速率为0.01~20 s^-1，并通过应力-应变曲线构建其热加工图。结果表明，随着铜含量的增加（0%Cu-304L，2.42%Cu-304L，3.60%Cu-304L），较好的热加工温度范围从200 ℃降低到75 ℃。微观组织分析发现：该材料失稳的主要原因有局部流动失稳、剪切带、空洞和裂纹；在热变形过程中，塑性变形能在短时间内转化为热量，导致变形材料局部温度升高，这使得熔点相对较低的铜偏析区易融化从而形成孔洞，成为裂纹的来源，降低了材料的热加工性。

Abstract:

The hot deformation behavior of Cu-bearing 304L stainless steel was studied by performing hot compression on Gleeble-3800 thermo mechanical simulator in the temperatures of 900~1150 ℃ and strain rates of 0.01~20 s^-1, and the processing maps were established by stress-strain curves. Results show that the better processing temperature range is narrowed from 200 °C to 75 °C with the increase of copper content in the alloy (0wt%Cu-304L, 2.42wt%Cu-304L, 3.60wt%Cu-304L). The alloy microstructure characteri-zation reveals that the main causes of instability are local flow instability, shear zone, void and cracking. At the same time, it is found that the plastic deformation can be converted into heat in a short time, leading to the local temperature rise of the deformed materials, which makes the copper segregation area with relatively low melting point easy to form holes and to become the source of cracking, and then reduces the hot workability.