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对Q235B钢板进行了总变形量为55%的冷轧,并进行了系列热处理。然后通过硬度测试和金相观察,研究了冷轧低碳钢组织在热处理中的转变过程。结果表明:试验钢冷轧后铁素体晶粒及珠光体呈方向性分布,晶粒被严重拉长。Q235B钢在两相区初期等温处理后,珠光体球化并逐渐减少,温度升高后仍可见极少量点状亚微米级珠光体。850℃等温5 min淬火后,钢的组织完全转化成马氏体。650℃等温较长时间淬火后,部分区域生成了准多边形铁素体,导致其硬度值高于550℃等温相同时间时的硬度。
The Q235B steel plate has a total deformation of 55% of the cold-rolled, and a series of heat treatment. Then the transition of cold-rolled mild steel structure in heat treatment was studied by hardness test and metallographic observation. The results show that the ferrite grains and pearlite are oriented in the direction of cold rolling and the grains are severely elongated. Q235B steel in the initial phase of the two-phase isothermal treatment, the pearlite spheroidization and gradually reduced, the temperature can still be seen after a small amount of spot-shaped submicron pearlite. After quenching at 850 ° C for 5 min, the microstructure of the steel is completely transformed into martensite. After quenching at 650 ℃ for a long time, the quasi-polygonal ferrite is formed in some areas, resulting in hardness higher than that at 550 ℃ for the same time.