摘要
以Q235、20MnSi钢坯为原料进行了用余热处理工艺生产英标460MPa级钢筋的试验,研究了水冷段数、水压、上冷床温度以及成分、钢种和时效对钢筋性能的影响。结果表明,Q235和20MnSi钢都可以利用余热处理工艺生产出性能合格的钢筋,但前者的生产成本较低;水压减小,钢筋强度降低,上冷床温度越高,强度越低,推荐5段水冷器全开,水压均为1.8~2.0MPa,Q235钢筋的上冷床温度应控制在650℃以下;钢筋典型的金相组织(Q235)表层为回火索氏体,过渡层为珠光体+铁素体且部分铁素体呈针状,心部为珠光体+铁素体,晶粒度8~10级;自然时效后屈服强度下降10~20MPa,用人工时效可以模拟自然时效,工艺是100℃×2h或200℃×1h。
Q235 and 20MnSi billets are. tested to produce BS 460MPa grade reinforced bar with postrolling residual heat treatment process. Influences of water-cooling stage, water pressure, the temperature at the entrance of cooling bed, compositions, steel grade and ageing on reinforced bar properties are studied,The results show that BS 460MPa grade reinforced bar can be produced all from Q235 or 20MnSi billet by the remained heat treatment process but the production cost of the former is lower. When the water pressure minishes, the intensities of reinforced bar reduce; the higher the temperature at the entrance of cooling bed is, the lower the intensities are. Therefore, the commendatory process parameters are that five stages coolers should be opened, water pressure should be all 1.8 -2.0MPa and the temperature at the entrance of cooling bed of Q235 reinforced bar should lower than 650%. The typical microstructure (Q235): the surface layer is tempered sorbite; the transition layer is pearlite and ferrite, and the partial ferrite is acicular; the core is pearlite and ferrite and the grain fineness is 8 - 10 grade. The yield strength is reduced by 10 - 20MPa after natural ageing and it can be simulated by artificial ageing( 100℃ × 2h or 200℃ ×1 h).
出处
《山东冶金》
CAS
2005年第5期35-38,共4页
Shandong Metallurgy