晶界结构对IF钢二次加工脆性的影响

Effect of Grain Boundary Structure on Secondary Working Embrittlement of IF Steels

采用电子背散射衍射(EBSD)技术和 TEM技术对 IF钢二次加工脆性与晶界结构之间的关系进行了研究。结果表明,在 IF钢板的低温冲压成形过程中,位错在高能随机晶界处大量塞积而萌生微裂纹,随后裂纹沿着连续网状的高能随机晶界迅速扩展而导致IF钢板二次加工脆性现象;IF钢板中低Σ值(Σ≤29)的CSL晶界和小角度晶界对裂纹的扩展起阻碍作用。

The effect of grain boundary structure on secondary working embrittlement (SWE) of IF steels was studied by electron back-scatter diffraction (EBSD) and TEM. The results show that the cracks nucleate at dislocations jamming at random boundary during deep-draw forming operation, and propagate along high energy continuous random boundary network, which lead to SWE of IF steels. Meanwhile, it has also been demonstrated that a crack can be arrested by low energy boundaries such as low-∑ CSL boundaries and low-angle boundaries.