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研究了变形量对一种低碳Mn-B-Ti系贝氏体型冷作强化非调质钢力学性能的影响。结果表明,随着变形量的增加,实验材料的强度逐渐增加而塑性逐渐降低,其中屈服强度较抗拉强度增加的幅度大。应变硬化指数n随γ增大为先增加后降低,即约在γ=30%时,n出现一峰值。冷拔变形后1/3冷镦变形时的压缩应力随γ增加基本不变,临界压缩变形量则随γ增大而不断降低。随着γ的增加,实验钢未充氢样的慢拉伸缺口抗拉强度逐渐增加,而充氢后试样的缺口抗拉强度σBN和延迟断裂强度比R则显著降低。实验钢拉拔后再经400℃时效处理能够使其延迟断裂性能得到显著恢复。因此,在满足强度要求的前提下,应选择合适的变形量,以保证材料的冷镦和延迟断裂等性能。
The effect of deformation on the mechanical properties of a low-carbon Mn-B-Ti bainitic cold-strengthened non-quenched and tempered steel was studied. The results show that with the increase of the deformation, the strength of the experimental material increases gradually while the plasticity decreases gradually, and the yield strength increases more than the tensile strength. The strain hardening index n increases first and then decreases with the increase of γ, that is, a peak appears at about n = 30%. After cold drawing deformation, the compressive stress at 1/3 cold heading deformation is basically unchanged with γ increasing while the critical compressing deformation decreases with γ increasing. With the increase of γ, the tensile strength of the slow tensile notch of the experimental steel without hydrogen increases gradually, while the notched tensile strength σBN and the delayed fracture strength ratio R of the experimental steel decrease significantly after the hydrogen filling. Experimental steel drawing and then 400 ℃ aging treatment can delay the fracture performance was significantly restored. Therefore, to meet the strength requirements under the premise should choose the appropriate amount of deformation to ensure that the material cold heading and delayed fracture performance.