摘要
T91钢经700℃时效50、100、300、500、850和1700 h后,进行SEM分析、EDS分析、析出相复型萃取TEM分析和力学性能测试分析,研究其组织性能随时间的变化规律,结果表明,随着时效时间的增加,析出相颗粒数量先增加后减少,时效850 h时达到最大,遵循N=9109+22.8t-0.02t^2关系;析出相颗粒尺寸一直增加,遵循D=0.53+5.86×10^(-4)t-1.06×10^(-7)t^2关系;析出相颗粒的面积总量一直增加,遵循S=6.5-5.0×e^((12.7-t)/504.1)关系;随时效时间的增加,基体中的Cr、Mo一直在向析出相中转移,进行合金元素再分配,在时效850 h有Laves相析出;随着时效时间的增加,强度、塑性指标总体呈下降趋势,在时效500 h时强度指标出现低值与晶粒长大和晶界弱化有关。时效产生的组织转变,使力学性能呈下降趋势。
T91 steel specimens aged at 700 % for 50 h, 100 h, 300 h, 500 h, 850 h and 1700 h, respectively, were analyzed by SEM, EDS, TEM and tensile tester to study the change rules of microstructure and properties with aging time extend. The results show that with the increase of aging time, the amount of precipitates increases at first and then decreases, and reaches the peak value when aged for 850 h, which corresponds with the function N = 9109 ＋ 22. 8t - 0. 02t2 ; the average size of precipitates continues to increase, which corresponds with the function D-0. 53 ＋ 5. 86 ×10-4t - 1.06 ×10-7t2; and the area fraction of precipitate phases increase all the time as well, which corresponds with the function S=6.5-5.0×e（12.7-t）/504.1. With the extension of the aging time, Cr and Mo in matrix migrate to precipitate phases and alloy element redistribution emerges and there appears Laves phase when aged for 850 h. As aging time goes on, strength indexes and plasticity indexes present a decreasing tendency. Strength indexes drop to the minimum when aged for 500 h which are related with grains grow up and reduction of grain boundaries. The microstructure changes during aging lead to a decrease tendency of mechanical properties.
出处
《金属热处理》
CAS
CSCD
北大核心
2017年第5期47-53,共7页
Heat Treatment of Metals
关键词
T91钢
时效
组织
性能
析出相
T91 steel
aging
microstructure
properties
precipitates
