板条马氏体晶宽纳米化及其力学行为

Lath Martensite Nanostructuring and its Effects on Mechanical Properties of Steel

对低碳低合金 30CrNiSiMoV钢采用奥氏体预应变淬火 ,可使板条马氏体板条晶宽细化至1 0 0nm ,板束尺寸达到 0 8μm以下 ,且板束方向多向化。对具备这种亚纳米结构马氏体组织的钢力学性能测试 ,发现其强度远超出了同类钢的常规极限水平 ,其抗拉强度σb 超过 1 80 0MPa,提高约 2 0 % ;屈服强度可达 1 70 0MPa以上 ,提高近 2 5 % ,伸长率δ≥ 1 0 %～ 1 2 % ,夏氏冲击韧度αk≥ 40～ 45kJ cm2 ,断口形貌由准解理型转变为准解理和韧窝的复杂准解理型 ,且韧窝的大小与亚纳米马氏体板条束宽度一致。研究取得了超常的强、韧化效果 。

Austenite\|prestrained quenching technology was employed to fine the microstructure of lath martensite of low carbon and low alloy 30CrNiSiMoV steel.The results show that the lath of martensite can be distinctively fined to nanometer scale with an average width of 100nm,and lath beam,length below 0\^8μm in different directions.The strength of the steel with fined microstructure is higher than the normal ultimate level of the steel.The tensile strength σ b and the yield strength σ s of the former exceeded 1800MPa and 1700MPa,which increase about 20% and near 25% than that of commercial 30CrNiSiMoV steel respectively.At the same time,the steel remaines high plasticity and toughness,and its percentage elongation δ and impact toughness value α k exceed 10%～12%,and 40～45kJ/m\+2,respectively.The fracture mode changes from quasi\|cleavage to quasi\|cleavge and dimple.The study provided a new approach to ultra\|fine microstructures of steels.