摘要
采用Gleeble-1500D型热力模拟试验机对DP980钢在不同温度(750,850,950℃)下保温2min,然后以不同的冷速(10,20,50℃·s~(-1))进行冷却,之后进行变形量为0.2%和2%的预应变,再进行170℃×20min的烘烤硬化处理,研究了热处理温度和冷速对DP980钢烘烤硬化性能的影响。结果表明:DP980钢具有较高的烘烤硬化性能,烘烤硬化处理后,铁素体中析出很多尺寸为10～20nm的析出相;当热处理温度为750℃和850℃时,烘烤硬化值随冷速的增加先减小后增大;当热处理温度为950℃时,烘烤硬化值随冷速增加而先增大后减小;在相同的冷速下,烘烤硬化值受热处理温度的影响很大,且冷速越大,影响也越大;当热处理温度为850℃、冷速为50℃·s~(-1)时,烘烤硬化值最高,此时的组织为细小的马氏体板条和铁素体。
With the help of Gleeble-1500 D thermomechanical simulator,the effects of heat treatment temperature and cooling rate on bake-hardening properties of DP980 steel were studied.The steel was treated at different temperature(750 ℃,850 ℃ and 950 ℃)for 2 min,and followed by cooling with cooling rates of 10,20,50 ℃·s~(-1);after that,pre-strains were carried out at deformation amounts of 0.2% and 2%,at last the bakehardening aging process was completed at 170 ℃for 20 min.The results show that,DP980 steel has higher bakehardening property because there are a lot of precipitates with size of 10-20 nm in ferrite after bake-hardening treatment;when heat treatment temperature was 750 ℃ and 850 ℃,the bake-hardening value firstly decreased and then increased as the cooling rate increased.But When the heat treatment temperature was 950 ℃,the bakehardening value exhibited the contrary trend.At the same cooling rate,the bake-hardening value is greatly affected by the heat treatment temperature,and the influence on the bake-hardening value would be greater when the cooling rate more faster.When the heat treatment temperature was 850 ℃ and the cooling rate was 50 ℃·s~(-1),the highest bake-hardening could be obtained,and the microstructure of the steel was fine martensite laths and ferrite.
引文
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