【摘要】 高强度化始终是钢的发展主题,同时还需要解决高强度化后导致的韧塑性降低、疲劳破坏和延迟断裂敏感性增加等问题。在获得高的力学性能之后,实际应用时还需要材料具有良好的工艺适应性与服役性能,达到合适的材料生产-零件制造-服役评价的技术匹配。本文以耐候钢、合金结构钢、紧固件用钢、高氮奥氏体不锈钢、马氏体不锈钢为案例,回顾并展望了与耐腐蚀、高强度、高品质等相关的材料发展动向。近年来的实践充分证明了技术基础研究是创新的源泉,从全产业链流程的组织与性能调控进一步转向合金化的再认识与利用,可能是今后一段时间应该考虑的问题。更多还原

【Abstract】 Strengthening and toughening are the main topics of steels, and accompanied fatigue failure and delayed fracture requiring to be solved simultaneously. Not just more than that, better performances in fabrication and service are quite important for an intentional steel to be used eventually. It is worth to pay close attention to match up three main courses: steel processing, component fabrication and service evaluation. Over past two decades, ferrite grains can be refined to micron scale in both plain low carbon steel products and microalloyed steel products and lead to remarkable increase of strength. The reason to define the limitation of ferrite grain refinement to microns is ductility decrease, low processing efficiency and heat affected zone(HAZ) coarsening. Ten years ago, a novel microstructure M~3(multiphase, metastable and multiscale) was proposed to overcome the problems stated above, and led to ductility and/or toughness improvement. It based on the idea of crack initiation and propagation retardment. It led to prevalence of the 3 rd generation advanced high strength steel(AHSS) and the 3rd generation high strength low alloy(HSLA) steel, presenting higher ductility and/or toughness at high strength level.In the near future, it is imaginable that polymorphic alloying will be taken into consideration instead of recent hot issue on microstructure control during whole processing. From the view point of classic alloying theory, solution and precipitation of alloying elements play an important role on processing and then final microstructure. The distribution and occurrence of small atom radius elements(e.g. C and N) and comparable atom radius elements(e.g. Cr, Mn, Ni, Co) in iron seem quite clear. The ambiguous situation still remains for B and P, and even larger atom radius elements such as rare earth(RE) elements. Segregation of small amount of them to defects and boundaries maybe lead to decrease of energy and result in remarkable change of microstructure characterization. Thanks to the advancement in processing and instrumentation technologies, the distribution and occurrence of alloying elements in steel and the advantages of different alloying elements in steel matrix and surface can be taken, so called the polymorphic alloying.The practices of polymorphic alloying in steel development are engaged to improve corrosion resistance, strengthening and toughening. The performance enhancements are discussed in cases of weathering steel microalloyed with RE, ultrahigh strength steel strengthening by carbide and intermetallic precipitates, bolt steel with C and microalloying elements, austenitic stainless steel alloyed with N, and martensitic stainless steel alloyed with C and Ag.更多还原