一种汽车发动机气阀用节镍型高温合金的固溶时效工艺

研究了不同热处理工艺下汽车发动机气阀用节镍型高温合金的微观组织、硬度及力学性能。试验结果表明,在900~1100 ℃固溶温度范围内,该材料的晶粒尺寸随温度的升高逐渐增大,硬度逐渐降低,1050 ℃后晶粒长大明显、急剧粗化,固溶温度宜选择为1000~1050 ℃,以保证主要强化相必要的析出条件且具有适宜的晶粒度;在700~760 ℃时效温度范围内,该材料的强度随时效温度的升高而逐渐增强,但韧塑性逐渐降低。当固溶时效工艺为1020 ℃×30 min固溶(水冷)+ 720 ℃×4 h时效(空冷)时,该节镍型高温合金可获得良好的强韧性匹配,满足技术要求。

Solution treatment and aging processes for a nickel-saving superalloy for automobile engine valve

Microstructure, hardness and mechanical properties of a nickel-saving superalloy for automobile engine valve treated by different heat treatments were studied. The results show that the grain size of the tested alloy increases and the hardness decreases with the increase of solution treatment temperature in the range of 900-1100 ℃. When the temperature exceeds 1050 ℃, the grains grow clearly and coarsen rapidly. The solution treatment temperature should be controlled in the range of 1000-1050 ℃ to ensure the necessary precipitation conditions of the main strengthening phase and to obtain appropriate grain size. In the range of 700-760 ℃, the strength of the tested alloy increases gradually with the increase of aging temperature, but the ductility decreases gradually. When the solution treatment and aging processes are 1020 ℃×30 min(solution treatment with water cooling)+720 ℃×4 h(aging with air cooling), the tested nickel-saving superalloy can obtain preferable combination of strength and toughness and can meet the technical requirements.