Practice and theory in the design of martensitic steels

早在欧洲铁器时代的第一个世纪，就有关于钢淬火的文字记录。在荷马笔下，我们发现“……就像铁匠用斧头或大斧头……把发出嘶嘶声的刀刃深深地插进冷水中：钢铁的力量从何而来……”调质钢的考古证据早在几个世纪前就存在了。回火被认为是为了降低淬火钢的极高硬度和脆性所必需的。另一方面，低成本淬火马氏体钢和冷拔珠光体钢的强度已达到极限。我们建议把取消回火工序的激进举措推向极限，设计出新的复相，如淬火、韧性、贫钢(低成本、资源高效)(Matles)。关键是利用最近获得的对体心立方金属塑性的理解；加工硬化；以及溶解碳、位错和金属碳氮化物之间的相互作用。这将与新的最先进的实验技术结合在一起：特别是进动电子显微镜和张应力松弛。这些强有力的结合将为我们提供操纵和开发层状板条马氏体微结构(HiLaMM)的手段。我们设计的新钢材将拥有出色的绿色资质：资源效率、可回收利用、高强度/重量比。我们的愿景是电动汽车经济、海上风电场结构组件的轻量化以及用于海底和土木工程项目的超强电缆。绕一圈，我们的成果将为材料科学的现代理论提供信息，为世界上一个突出的科学问题提供解决方案：加工硬化的本质是什么？(为什么我不能把你刚才弄弯的扑克牌弄直？)

Written records of the quenching of steel exist as early as the first century of the European Iron Age. In Homer we find "... As when the smith an hatchet or a large axe ... plunges the hissing blade deep in cold water: whence the strength of steel ..." Archeological evidence for quenched and tempered steel exists from several centuries earlier. Tempering has been regarded as essential in order to mitigate the extreme hardness and brittleness of as-quenched steel. On the other hand the strength limit has been reached in low cost hardened martensitic and hard-drawn pearlitic steels. We propose to push the envelope making the radical move of dispensing with the tempering step and designing new multiphase, as quenched, tough, lean (low cost, resource efficient) steel (MATLeS). The key is to exploit recently acquired understanding of the plasticity of body centered cubic metals; work hardening; and interplay between dissolved carbon, dislocations and metal carbonitrides. This will be put together with novel state-of-the-art experimental techniques: in particular precession electron microscopy and tensile stress relaxation. In powerful combination these will furnish us with the means to manipulate and exploit the hierarchical lath martensite microstructure (HiLaMM). The new steels we design will have excellent green credentials: resource efficiency, recyclability, high strength-to-weight ratio. Our vision is toward the electric vehicle economy, light-weighting of structural offshore wind farm components and super-strong cables for undersea and civil engineering projects. Making full-circle, our outcomes will inform modern theories in materials science, advancing solutions to one of the world's outstanding scientific questions: what is the nature of work hardening? (Why can I not straighten the poker you have just bent?)