超高强钢23Co14Ni12Cr3强韧性的优化配合

On Optimizing Combination of Strength and Toughness of Ultra-High Strength Steel 23Co14Ni12Cr3

主要考察了双时效工艺对超高强钢 2 3Co1 4Ni1 2 Cr3显微组织与力学性能的影响。在抗张强度没有明显降低的条件下 ,新创立的双时效比正常时效的冲击疲劳寿命与动态断裂韧性分别延长和提高了 35 .5 %与 2 2 .6%。结果表明 :双时效工艺在改善高强钢的强韧性优化配合方面是一新的突破。基于显微组织的观察结果 ,深入地分析了逆转变奥氏体 AR 稳定性提高和疲劳寿命延长的物理机制 ,不仅双时效的高温保温阶段所形成的 AR 韧性得到大幅度提高 ,而且在双时效的低温处理过程中 ,从马氏体铁素体中析出的间隙碳原子会扩散到逆转变奥氏体中 。

This investigation aims at improving the toughness of ultra-high strength steel 23Co14Ni12Cr3 at the cost of just a small lowering of strength, thus optimizing the combination of strength and toughness. By our new way of double aging, on which we have done research since 2002, the impact fatigue life can be prolonged by 35.5 % and dynamic fracture toughness can be raised by 22.6 % respectively, as compared with the normal aging; strength is just lowered by 5.8 %. On the basis of microstructure study, we have analyzed in depth the physical mechanism of the prolongation of fatigue life and the enhancement of stability of the reverted austenite. Here we just give a very concise analysis of this physical mechanism. In the light of our current understanding, not only is the toughness of reverted austenite formed in process of heat preservation at higher temperature of double aging increased by a big margin, but also, during the treatment of lower temperature of double aging, the carbon separating from the martensitic ferrite of 23Co14Ni12Cr3 steel will certainly diffuse into the reverted austenite, as a result, the brittleness of austenite is decreased and the stability is increased.