经过不同的时效处理研究了固溶C含量对ULC-BH 钢抗自然时效性能的影响。试验结果表明,ULC-BH 钢在170℃×500 min的长时间烘烤过程中,固溶C原子会发生偏聚并形成柯氏气团,BH2与Ae值逐渐增加；当柯氏气团达到饱和后,BH2与 Ae 值出现平台,之后变化不大；固溶C含量越高,相应的 BH2值越大；当固溶 C 含量为18.9 ppm 时,BH2值为46.2 MPa；固溶C含量为32.5 ppm时,BH2值可以达到74.4 MPa；同时固溶C含量越高,引起屈服强度与Ae值均变大,但是为保证 ULC-BH 钢板经自然时效后的成形性能,钢板固溶 C 含量不应过高,当平整量为1%时,固溶C含量为18.9 ppm的钢板的性能较好。%The effect of solution carbon content on natural aging resistance of the ultra-low-carbon bake hardening steel sheet by different aging treatments were studied.The results show that when the steels are aged at 170 ℃ for 500 min,solute carbon atoms will segregate and formate Cottrell atmospheres,the in-crement in yield stress BH2 and yield point elongation Ae increase with it;after atmosphere saturation, both BH2 and Ae remain constant or change slightly with further aging;with the increasing of the solution carbon content,the maximum increment BH2 is higher,the maximum increment BH2 of the solution car-bon content 32.5 ppm is 74.4 MPa,the solution carbon content 18.9 ppm is 46.2 MPa;meanwhile with the increasing of the solution carbon content,both yield strength and Ae are higher;but in order to ensure the formability after natural aging,the solution carbon content should not be too high,on the condition of the flat amount was 1%,the performance of the steel containing the solution carbon content 18.9 ppm is bet-ter.
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