合金钢淬火-配分工艺研究进展

 随着国内冶金、机械等领域的不断发展,对钢铁材料性能的要求越来越严格,汽车用钢不仅要求减重而且要有足够高的抗冲击性能保证汽车安全性,耐磨材料不仅要保证硬度还要有良好的韧性。合金钢淬火-配分(quenching and partitioning,简称Q&P)工艺是由美国Speer J G教授在2003年受Trip钢启发提出的,最终目的是在硬相基体上获得一定量的软相残余奥氏体,从而提高钢的塑韧性,马氏体、贝氏体保证了强度,残余奥氏体可以提高韧性,两相结合拥有良好的综合力学性能。和传统工艺淬火-回火(QT)抑制碳化物析出不同,钢中的碳没有分解为碳化物,而是在保温过程中重新扩散至奥氏体,提高了奥氏体的稳定性。Q&P钢具有成本低、性能好、工艺相对简单等特点,最初应用到汽车高强钢上,可以很大程度减轻汽车的质量、提高防撞能力、减小变形程度;陆续有研究者将Q&P工艺应用到耐磨材料上,发现可以在耐磨性损失很小或者不损失的情况下大幅度提高韧性。为了进一步提高性能,国内外许多学者做了大量的研究,在Q&P热处理工艺优化方面,发现奥氏体化温度、淬火工艺、配分工艺等参数对Q&P钢组织和性能都有较大影响;在合金元素调控方面,不仅C、Mn、Si等常规合金元素对Q&P钢的性能有重要的影响,Nb、Mo等微合金元素也对Q&P钢组织和性能有较大的影响。主要阐述了Q&P工艺的发展、国内外的研究现状以及Q&P工艺的应用,最后对Q&P工艺未来的发展进行了展望和总结。

Research progress of quenching and partitioning process for alloy steel

With the continuous development of metallurgy, machinery and other fields in China, the requirements for the properties of iron and steel materials are becoming more and more strict. Automotive steel is required not only to lose weight but also to have high enough impact resistance to ensure safety. Wear-resistant materials should have not only strong hardness but also good toughness. The Quenching and Partitioning (Q&P) process of alloy steel was proposed by Professor Speer J G of the United States in 2003 inspired by Trip steel. The ultimate goal is to obtain a certain amount of soft phase retained austenite on the hard phase matrix, so as to improve the plasticity and toughness of the steel. Martensite and bainite ensure strength and retained austenite can improve toughness, and the combination of the two phases has good comprehensive mechanical properties. Different from the traditional process of quenching tempering (QT) inhibiting carbide precipitation, the carbon in the steel is not decomposed into carbide, but is rediffused to austenite in the process of heat preservation, which improves the stability of austenite. Q&P steel has the characteristics of low cost, good performance and relatively simple process, when initially applied to automobile high strength steel, it can greatly reduce the weight of automobile, improve anti-collision ability and reduce the degree of deformation. In succession, some researchers have applied Q&P process to wear-resistant materials, and found that the toughness can be greatly improved with little or no loss of wear resistance. In order to further improve the properties, many researchers at home and abroad have done a lot of research. In the optimization of heat treatment process, it is found that the parameters such as austenitizing temperature, quenching process and partitioning process have great influence on the microstructure and properties of Q&P steel. In terms of alloying element control, not only conventional alloy elements such as C, Mn and Si have important influence on the properties of Q&P steel, micro alloying elements such as Nb and Mo also have great influence on the microstructure and properties of Q&P steel. The proposal and development of Q&P process were described mainly, the research status at home and abroad, and the application of Q&P process were discribed mainly. Finally, the future development of Q&P process is prospected and summarized.