屈服强度1100 MPa级超高强钢热处理组织及性能

摘要：随着工程机械向大型化轻量化方向发展，超高强钢的市场需求越来越大且综合性能要求越来越严格。结合5000mm宽厚板生产线及热处理装备，研究淬火过程中淬火温度对屈服强度1100MPa级超高强度钢组织及力学性能的影响。结果表明，淬火温度决定了合金元素的溶解和分布状态、原始奥氏体晶粒尺寸，影响试验钢的综合力学性能。不同淬火温度下，基本微观组织为板条马氏体。随着淬火温度的升高，原奥氏体晶粒尺寸增大；当淬火温度由840℃升高至990℃时，原奥氏体晶粒平均尺寸由9.0μm增加到22.5μm。采用900～930℃淬火及350℃回火的热处理工艺，试验钢可获得最佳的强韧性匹配，此时屈服强度为1125～1155MPa、抗拉强度为1306～1335MPa、断后伸长率为12.5%～14.0%，布氏硬度为415～419，－40℃冲击功为80～100J，抗拉强度与布氏硬度比值范围在3.10～3.20之间，满足标准GB/T 28909—2012对Q1100E的要求。

Microstructures and properties of 1 100MPa grade ultra high strength steel after heat treatments

With the development of construction machinery steel towards large scale and lightweight, the market demand of ultra high strength steel has been increasing and requirements for its comprehensive properties get more and more strict. The production line and heat treatment equipment of 5000mm wide plate were employed to investigate the effects of quenching temperature on the microstructures and mechanical properties of 1100MPa grade ultra high strength steel. Results show that the dissolution and distribution of alloying elements, the grain size of primary austenite, and the mechanical properties of experimental steel are determined by the quenching temperature. At different quenching temperatures, the basic microstructures of experimental steels are all lath martensite. As quenching temperatures increasing, the grain size of primary austenite gradually increases. When the quenching temperature increases from 840℃ to 990℃, the average grain size of primary austenite is increased from 9.0μm to 22.5μm. By adopting the heat treatment processes of quenching at 900-930℃ and tempering at 350℃, the best combination of strength and toughness of experimental steel can be achieved: With yield strength of 1125-1155MPa, tensile strength of 1306-1335MPa, elongation of 12.5%-14.0%, Brinell hardness of 415-419, impact toughness at -40℃ of 80-100J, and the ratio of tensile strength and Brinell hardness of 310-320, the experimental steel can meet the requirements of GB/T 28909-2012 for Q1100E.