Q420q-E厚板回火工艺探讨.pdfVIP

Q420q-E 厚板回火工艺探讨 杨云清 谭小斌 曹 波 刘 丹1 （湖南华菱湘潭钢铁有限公司，湘潭 411101 ） 摘 要 本文针对 Q420q-E 厚板回火出现的屈强比升高的生产实际问题，对 Q420q-E 不同回火温度的组织转变进 行研究，发现了不同回火工艺过程中析出物对钢板屈服强度的影响规律。Q420q-E 生产中屈强比上升的主要原因 是回火温度偏高，钢板中第二相ε-Cu 颗粒及铌、钛的析出相，屈服强度上升；较低温度回火后，钢板内应力得 以消除，钢板保持了TMCP 的组织特征，低温冲击韧性保持较高水平，屈服强度没有明显上升，屈强比基本保持 不变。提出了符合现场实际生产条件的回火工艺，即：500 ±10℃、（板厚+55 ）min 、空冷，该工艺成功地应用于 实际生产, 生产的 Q420q-E 厚板满足了我国第一代高速、重载公铁两用大胜关长江大桥建设的要求。 关键词 回火工艺 析出物 屈强比 Temper Process Study of Q420q-E Thick Plates Yang Yunqing Tan Xiaobin Cao Bo Liu Dan (Xiangtan Iron Steel Co., Ltd., Institute of Heavy Plate, Xiangtan, 411101) Abstract The effects of tempering temperatures on phase transformation of Q420q-E thick plates were studied due to the increasing yield ratio problem during tempering of the thick plates’ production. The influences of the precipitation on plates’ yield strength under different tempering process were showed. It was demonstrated that high tempering temperature was the main reason to increase the yield ratio during the Q420-E production, the second phase ε-Cu and the precipitates of Nb and Ti made the yield strength increase. However, the internal stress was relieved, the microstructural characteristics of TMCP was kept, low temperature impact toughness was kept at a high level, the yield strength had little increase and the yield ratio was almost kept unchanged under the low temperature tempering process. Then the actual tempering process for production was indicated, that was 500 ±10℃, （the plate thickness +55 ）min and air cooling. The process had already been applied in production, with which the Q420q-E thick plates had met the demand of the construction of China’s first generat