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对二次硬化超高强度AerMet 100钢,通过引入预时效并优化双时效(即预时效+正常时效)工艺,膜状逆转变奥氏体(AR)中合金元素Ni、Co含量的起伏有利于提高其稳定性并降低Ms温度。高分辨透射电子显微镜(HRTEM)与扫描电子显微镜(SEM)分析表明:膜状AR在原奥氏体晶粒及马氏体铁素体(MF)板条边界形成,其间同时存在的K-S和N-W位向关系使有效晶粒由原奥氏体晶粒减小为MF板条(其厚度约80 nm);试样断面大而深的韧窝及高的撕裂棱反映出裂纹尖端钝化和分岔会吸收大量能量,在抗拉强度(σb)>2000 MPa条件下断裂韧度(KIC=127 MPa.m1/2)提高20%。
For the second hardened ultra-high strength AerMet 100 steel, the fluctuation of the Ni and Co content in the film-like reverse-transformed austenite (AR) is facilitated by the introduction of a pre-aging and optimization of the dual aging (ie pre-aging + normal aging) Improve its stability and reduce Ms temperature. High-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) analysis showed that the membranous AR was formed at the boundaries of the original austenite grains and the martensite ferrite (MF) lamella, with simultaneous presence of KS and NW The relationship between the effective grain from the original austenite grains reduced to MF lath (the thickness of about 80 nm); sample section of the deep and deep dimples and tear edges reflect the crack tip passivation and points The fork can absorb a large amount of energy and increase the fracture toughness (KIC = 127 MPa.m1 / 2) by 20% under the condition of tensile strength (σb)> 2000 MPa.