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利用金相显微镜、X射线衍射等方法研究了0.15C-1.46Si-1.56Mn-0.06Nb冷轧TRIP钢板等温淬火温度对组织和力学性能的影响。结果表明,试验钢最佳的临界热处理工艺:在840℃两相区保温180 s,再快速冷却到420℃并在该温度保温240 s,进行贝氏体等温转变处理。采用这种热处理工艺,试验钢的微观组织为铁素体+贝氏体+残留奥氏体,其中铁素体占72%,贝氏体占20%,残留奥氏体占8%,可获得较佳的相变诱发塑性和较好的强韧性配合,其强塑积可达到2.5×104MPa.%,提高或降低贝氏体等温淬火温度都会降低强塑积。结果还表明,在840℃,适当的延长热处理时间可以提高残留奥氏体体积分数及残留奥氏体的碳含量,有助于提高材料的强塑积。
The microstructure and mechanical properties of 0.15C-1.46Si-1.56Mn-0.06Nb cold-rolled TRIP steel were studied by means of optical microscope and X-ray diffraction. The results show that the best critical heat treatment process for the test steel is that the bainite isothermally transformed at 840 ℃ for 180 s in the two-phase zone, cooled rapidly to 420 ℃ and kept at that temperature for 240 s. Using this heat treatment process, the microstructure of the test steel is ferrite + bainite + retained austenite, of which ferrite accounts for 72%, bainite accounts for 20% and retained austenite accounts for 8% Better phase transition induced plasticity and better toughness with the strong plastic product can reach 2.5 × 104MPa%, increase or decrease bainite austempering temperature will reduce the strong plastic product. The results also show that extending the heat treatment time appropriately at 840 ℃ can increase the volume fraction of retained austenite and the carbon content of retained austenite, which helps to improve the material ’s strong plasticity.