水电用SX780CFZ35特厚板热处理工艺研究

Study on heat treatment process of SX780CFZ35 heavy plate for hydropower station

针对水电用SX780CFZ35特厚钢板需具备易焊接、高强度、良好的塑性和低温韧性的要求,研究了热处理工艺对其力学性能及金相组织的影响。结果表明,在相同淬火温度下,钢板屈服强度、抗拉强度随回火温度的升高而降低,但冲击功随回火温度的升高而升高,屈强比则呈先上升后下降的趋势。在相同回火温度下,随淬火温度的升高,钢板强度增加,冲击功降低。820℃淬火,钢板组织存在较大比例未溶铁素体,为贝氏体和细小铁素体双相组织;860℃以上淬火,钢板组织为贝氏体,回火后为回火索氏体组织。热处理工艺为900℃淬火+620℃回火时,钢板冲击功达到100 J以上,强度依然能符合技术协议要求,为最佳热处理工艺。

According to the requirements of easy welding,high strength,good plasticity and low temperature toughness of SX780 CFZ35 heavy plate for hydropower station,the effect of heat treatment process on its mechanical properties and metallographic structure was studied.The results show that under the same quenching temperature,the yield strength and tensile strength of the plate are decreased with the increasing of tempering temperature,but the impact energy is increased with the increasing of tempering temperature,and the yield ratio is increased first and then decreased.At the same tempering temperature,as the quenching temperature increaseing,the strength of the plate is increased and the impact energy is decreased.Quenched at 820 ℃,there is a large proportion of undissolved ferrite in the plate structure,which is a dual phase structure of bainite and fine ferrite;quenched above 860 ℃,the plate structure is bainite,and after tempering,it is tempered sorbite organization.The heat treatment process is 900 ℃ quenching and 620 ℃ tempering,the impact energy of the plate is reached more than 100 J,and the strength can be meet the requirements of the technical agreement,which is the best heat treatment process.