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在RILNL-78热膨胀系数测定仪上进行微合金化SWRCH6A钢热模拟试验,采用热膨胀法和金相法建立CCT曲线,研究添加微量硼、钛元素后SWRCH6A钢连续冷却过程中的相变规律。结果表明,随着冷却速率的增加,微合金化SWRCH6A钢的显微组织构成由多边形铁素体PF逐步转变为多边形铁素体PF、珠光体P和准多边形铁素体QF,最终转变为珠光体P、准多边形铁素体QF和粒状贝氏体GB;随着冷却速率的增加,SWRCH6A钢的维氏硬度逐渐增加;结合SWRCH6A钢的CCT曲线,确定出合适的轧后冷却速率为0.5℃·s~(-1),此冷却速率下可得到理想的显微组织:准多边形铁素体QF+多边形铁素体PF+珠光体P。
The micro-alloyed SWRCH6A steel was simulated on the RILNL-78 thermal expansion coefficient tester. The CCT curve was obtained by thermal expansion method and metallographic method. The phase transformation of SWRCH6A steel after continuous addition of boron and titanium was studied. The results show that microstructure of SWRCH6A microalloyed steel gradually changes from polygonal ferrite PF to polygonal ferrite PF, pearlite P and quasi-polygonal ferrite QF with the increase of cooling rate, and finally transformed into pearlescent Body P, quasi-polygonal ferrite QF and granular bainite GB. With the increase of cooling rate, the Vickers hardness of SWRCH6A steel gradually increases. Combined with the CCT curve of SWRCH6A steel, the suitable cooling rate after rolling is determined as 0.5 ℃ · S ~ (-1). At this cooling rate, the ideal microstructure is obtained: quasi-polygonal ferrite QF + polygonal ferrite PF + pearlite P.