两相区连续退火均热温度对Q&P980钢组织性能的影响

以冷轧Q&P钢的连续退火生产为工艺背景,采用两相区均热保温+缓冷+快冷至Ms与Mf点之间进行配分的热处理工艺,研究了两相区不同均热温度对低碳硅锰系Q&P980合金高强钢微观组织和力学性能的影响。结果表明,随着两相区均热温度的升高,铁素体含量降低,马氏体所占比例升高,且板条尺度有所增加;随着均热温度的升高,残留奥氏体含量先升高至最大值(7.2%)后降低;随着均热温度继续升高,基体内部马氏体的含量增加,导致材料抗拉强度增加,而伸长率的变化趋势则与残留奥氏体含量变化趋势相似;在配分温度为310 ℃时,最佳的均热温度区间为765.24~812.56 ℃,其中在790 ℃均热时,抗拉强度为1052 MPa,伸长率为22.9%,强塑积为24 090.8 MPa·%。

Effect of intercritical continuous annealing temperature on microstructure and properties of Q&P980 steel

Taking continuous annealing production of cold rolled Q&P steel as the technological background, the heat treatment process of soaking and heat preservation in two-phase zone+slow cooling+rapid cooling to partitioning between Ms and Mf points was adopted, and the effects of different soaking temperatures in the two-phase zone on microstructure and mechanical properties of low-carbon silicon manganese alloyed Q&P980 high-strength steel were studied. The results show that with the increase of soaking temperature in the two-phase region, the ferrite content decreases, the proportion of martensite and lath size increases, the content of retained austenite first increases to 7.2% and then decreases. With the further increase of soaking temperature, the tensile strength increases monotonically due to the increase of martensite content in the matrix, while the change trend of elongation is similar to that of retained austenite content. When the partitioning temperature is 310 ℃, the best soaking temperature range is 765.24-812.56 ℃. When soaking at 790 ℃, the tensile strength is 1052 MPa, the elongation is 22.9%, and the strength-elongation production is 24 090.8 MPa·%.