时效工艺对25Cr-20Ni-2.5Al高强耐热钢拉伸和高温压缩性能的影响

通过在25Cr-20Ni耐热钢基体成分中加入质量分数为2.5%Al的方式制备25Cr-20Ni-2.5Al耐热钢,分别采用拉伸和高温压缩试验对其力学性能进行表征分析,研究结果表明:经过36 h时效处理的试样抗拉强度得到明显提升,此时抗拉强度和伸长率分别为803 MPa和27.1%。经过36 h时效处理会减小拉伸断口的韧性,生成部分脆性断裂的痕迹。随时效温度的增加,耐热钢的抗拉强度先增大后减小,伸长率先减小后增大,转折点均出现在时效温度650 ℃,此时抗拉强度和伸长率分别为451 MPa和10.26%。当变形程度增大后,晶粒将达到更大的变形程度,而耐热钢经过热压缩处理后并不会引起晶粒尺寸的明显改变;晶界部位存在析出相,而且当变形量增大后析出相的数量也会略微增加。

Effect of aging process on tensile and high temperature compressive properties of 25Cr-20Ni-2.5Al high strength heat-resistant steel

25Cr-20Ni-2.5Al heat resistant steel was prepared by adding 2.5% Al in 25Cr-20Ni heat-resistant steel and its mechanical properties were characterized and analyzed by means of tensile and high temperature compression experiments, respectively. The results show that the tensile strength of the sample after 36 h aging treatment is significantly improved, and the tensile strength and elongation are 803 MPa and 27.1%, respectively. After 36 h aging treatment, the toughness of the tensile fracture is reduced and the traces of partial brittle fracture are generated. With the aging temperature increasing, the tensile strength of the heat-resistant steel increases first and then decreases, while the elongation decreases first and then increases. The turning point occurs at the aging temperature of 650 ℃, when the tensile strength and elongation are 451 MPa and 10.26%, respectively. When the deformation degree increases, the grain reaches a larger deformation extent, while the grain size of the heat-resistant steel does not change obviously after thermal compression treatment. Precipitation phase also exists at the grain boundary, and the number of precipitation phase increases slightly when the deformation increases.