微合金高强钢纳米相间析出行为研究进展

 提高强度的同时不降低韧性,是人们在高强钢研发过程中追求的目标。相较于其他强化方式,细化晶粒可以使材料的强度和韧性同时提高,但目前为止钢铁材料晶粒尺寸最小可控制到3～5 μm,所能带来的强化效果有限。新型铁素体基高强钢通过相间析出使铁素体基体上分布着有规则排列的纳米尺寸碳化物,大大提高强韧性能、可成型性和焊接性,广泛应用于工程机械、石油管线、汽车零部件以及高层建筑领域。近几年随着钢铁行业的发展,对于相间析出的了解也越来也深入,各种微合金钢的纳米相间析出特征已有大量报道,主要集中在析出物微观结构特征与强度贡献的研究上。然而,相间析出机制以及模型还存在许多争议,通过工艺控制实现稳定的相间析出还比较困难,纳米相间析出高强钢的性能稳定性还较差。随着科技的发展,相关先进分析仪器也在更新换代,为新型铁素体基高强钢纳米尺度碳化物相间析出行为的深入研究提供了条件。综述了铁素体基高强钢纳米尺度碳化物相间析出的国内外研究动态,阐明了台阶理论与溶质消耗理论的局限性;对铁素体基高强钢的成分设计进行了分析,揭示了合金化方式对相间析出行为的影响规律;介绍了目前国际上研究纳米尺度碳化物相间析出行为的先进仪器及技术,最后对新型铁素体基高强钢的发展进行了展望,指出复合微合金化表现出的优势将会是以后微合金钢发展的必然趋势。

Research progress on nano-scale interphase precipitation behavior of microalloyed high-strength steel

Increasing strength without reducing toughness is the goal that people pursue in the research and development process of high-strength steel. Compared with other strengthening methods, grain refinement can increase the strength and toughness of the material at the same time,but the minimum grain size of steel materials can be controlled to 3-5 μm now,and the strengthening effect that can be brought about is limited. A new type of ferrite-based high-strength steel has been developed in the past ten years. Through interphase precipitation,the ferrite matrix is distributed with regularly arranged nano-sized carbides,which greatly improves the toughness,formability and weldability,and is widely used in the field of construction machinery,oil pipelines,auto parts and high-rise buildings.With the development of the iron and steel industry in recent years,the understanding of the interphase precipitation has become more and more in-depth. There have been a large number of reports on the nanophase precipitation characteristics of various microalloyed steels,mainly focusing on the study of the microstructure characteristics and strength contributions of the precipitates. However,there are still many disputes about the interphase precipitation mechanism and model. It is still difficult to achieve stable interphase precipitation through process control,and the performance stability of nanophase precipitation of high-strength steel is still poor. With the development of science and technology,relevant advanced analytical instruments are also being updated, providing conditions for in-depth research on the precipitation behavior of nano-scale carbide phases in new ferrite-based high-strength steels. Based on this,the domestic and foreign research developments on the precipitation of nano-scale carbides in ferrite-based high-strength steels were reviewed,and clarifies the limitations of step theory and solute consumption theory;the composition design of ferrite-based high-strength steels was analyzed. The influence of the alloying method on the interphase precipitation behavior was revealed;the current international advanced instruments and technologies for studying the interphase precipitation behavior of nano-scale carbides were introduced. Finally,the development of the new ferrite-based high-strength steel was prospected,and the advantages of composite microalloying will be the inevitable trend of microalloying steel development in the future.