Development of Roll Formable Ultra High Strength Steels for Energy Efficient Manufacture of Lightweight Crash Resistant Automotive Structures

该项目涉及超高强度钢（UHSS -极限抗拉强度大于1000 MPa的钢）的开发，专门设计用于通过新型低能量和灵活的制造工艺（称为3D辊轧成形）形成，以生产汽车行业的轻质防撞结构。辊轧成形工艺是一种增量弯曲工艺，与传统的冲压工艺相比，该工艺将平板变成结构轮廓，传统的冲压工艺涉及板的严重拉伸以产生所需的零件几何形状。3D滚轧成形工艺非常灵活-该技术的领先开发人员声称，一套工具可以用于制造多达四分之一的汽车结构，而冲压工艺则需要为每个零件制造一套昂贵的工具。此外，与冲压生产线的18个月相比，辊压成型生产线仅需10至16周即可安装。目前，超高强度汽车钢通常使用能量密集型热冲压形成，因为设计实现所需的高室温均匀延展性与超过1000 MPa的极限拉伸强度的组合的钢是非常困难和昂贵的。由于辊轧成形仅要求材料是可弯曲的，因此建议具有低加工硬化率和高屈服比（屈服强度/极限抗拉强度）的钢可以适合于使用该工艺成形。用于辊轧成形的UHSS的开发允许更简单的成分，更精简，合金成本更低，从而减少了原材料供应问题（稀缺性）的风险，与现有能力具有更好的兼容性，并且更一致（更高的产量/更低的废料）。这可能是一项颠覆性的技术，可以彻底改变汽车结构件的制造。它将：消除了目前用于成形UHSS的能源密集型热冲压的需要;显著降低了模具要求和制造过程中的相关能源;提高了材料利用率;避免了使用铝、镁和CFRP等能源密集型材料进行轻量化的需要;同时生产出的产品在使用过程中将显著节省二氧化碳。据估计，如果辊压成型钢取代了汽车中50公斤的热冲压部件，那么英国汽车制造业每年可以节省40，000吨二氧化碳。

This project is concerned with the development of Ultra High Strength Steels (UHSS - steels with a ultimate tensile strength greater than 1000 MPa) specifically designed to be formed by a novel low energy and flexible manufacturing process, known as 3D roll forming, to produce lightweight crash resistant structures for the automotive industry. The roll forming process is an incremental bending process that turns a flat sheet into a structural profile as compared to traditional stamping processes that involves severe stretching of the sheet to create the required part geometry. The 3D roll forming process is extremely flexible - leading developers of the technology claim a single set of tooling can be used to manufacture up to a quarter of the automotive structure, whereas the stamping process requires an expensive set of tools to be manufactured for each individual part. Furthermore a roll forming line only take 10 to 16 weeks to setup as compared to 18 months for a stamping line. Today ultra high strength automotive steels are usually formed using the energy intensive hot stamping as it is very difficult, and costly, to design steels that achieve the required high room temperature uniform ductility in combination with an ultimate tensile strength in excess of 1000 MPa. As roll forming only requires the material to be bendable, it is proposed that steels with low work hardening rates and a high yield ratio (yield strength /ultimate tensile strength) could be suitable for shaping using this process. The development of UHSS for roll forming allows simpler compositions that are leaner and have a lower alloy cost which reduces exposure to raw materials supply issues (scarcity), have better compatibility with existing capabilities and are more consistent (higher yield/lower scrap). This is potentially a disruptive technology that could revolutionise the manufacture of automotive structural members. It will: eliminate the need for energy intensive hot stamping currently used for shaping UHSS; dramatically reduce tooling requirements and the energy associated in their manufacture; increase material utilisation; avoid the need to use energy intensive materials for lightweighting such as Al, Mg and CFRP; all whilst producing a product that will yield significant CO2 savings during use. It is estimated that if roll formed steel replaced 50 kg of hot stamped components in a vehicle, then 40,000 tonnes of CO2 could be saved in the UK automotive manufacturing industry per annum.