【摘要】 研究了浇注后不同的冷却速率对MX246A合金组织和持久性能的影响。结果表明,组织特征只受该组织形成时的冷速影响。冷速从30℃/min降到8℃/min时,晶粒增大,共晶γ′的体积分数从1.86%减少到0.86%,尺寸从30μm增大至50μm;冷速从30℃/min降到4℃/min时,枝晶干γ′尺寸由0.93μm增大至3.09μm,边界由平直转为圆滑,碳化物颗粒变大,数量减少;枝晶干γ′和碳化物的尺寸和形貌对高温持久性能影响较大。当冷速为30℃/min时,获得较小尺寸、边界平直的枝晶干γ′和细小弥散分布的碳化物,持久性能较好。更多还原

【Abstract】 Effects of different cooling rates after pouring on microstructures and stress rupture properties of MX246A alloy have been studied. The results show that microstructures of MX246A alloy are influenced only by the cooling rate at the certain time when the microstructures are formed. With the reduction of cooling rate from 30 ℃/min to 8 ℃/min, size of grains becomes lager, volume percent of primary γ′ decreases from 1.86% to 0.86% and size of primary γ′ increases from 30 μm to 50 μm; when cooling rate reduces from 30 ℃/min to 4 ℃/min, size of dendrite stem γ′ changes from 0.93 μm to 3.09 μm with its morphology from rectangular to cellular. It is concluded that size and morphology of dendrite stem γ′ and carbides are the most important contributions to high temperature stress rupture property; when the cooling rate is 30 ℃/min, stress rupture property of MX246A is better, which may be attributed to the small and rectangular dendrite stem γ′ and fine and dispersed carbides.更多还原