摘要:
采用热模拟试验机、高分辨透射电镜及金相显微镜等设备研究了V-Ti试验钢连续冷却相转变和强化机制。结果表明,低冷速下(0.5~1.5℃/s),组织为铁素体和珠光体;冷速增加(1.5~5℃/s),发生贝氏体相变,且贝氏体比例逐渐增加;高冷速状态(5~25℃/s),马氏体出现并逐渐作为主体组织。V-Ti试验钢强化机制主要为析出沉淀强化和细晶强化,晶粒内部弥散析出10~60 nm圆角矩形的V(C,N)+TiN粒子。优化冷速1.0~1.5℃/s开展25 mm HRB600产线试制,屈服强度≥630 MPa,抗拉强度≥820 MPa,断后伸长率≥20%,最大力总伸长率≥11%,强屈比≥1.25。
Abstract:
Continues cooling phase transformation behavior and strengthening mechanisms of the V-Ti containing rebarsteel were systematically studied by thermal simulation testing machine,HR-TEM and OM.The result showed that the microstructure of used rebar was composed of ferrite and pearlite at 0.5～1.5 ℃/s cooling rate; the bainite transformation occurred and the ratio of bainite increased at 1.5～5 ℃/s cooling rate; the martensite structure appeared and gradually become the main structure at 5～25 ℃/s cooling rate.The strengthening mechanisms of V-Ti containing test steel were mainly precipitation strengthening and fine-grain strengthening,and V（C,N）+TiN mainly precipitated as rounded rectangle fine particles dispersing and its size was 10～60 nm.The V-Ti containing rebar was pilot-manufactured by using cooling rate of 1.0～1.5 ℃/s,which shows yield strength above 630 MPa,tensile strength above 820 MPa,elongation of 20%,maximum gross elongation of 11%,and the ratio of tensile strength and yield strength of 1.25.
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