Thermomechanical aspect and high-strain rate behavior of next generation advanced high-strength materials

点击翻译按钮获取中文摘要

The Canadian government and automotive industries regularly review the policies, standards and regulations to ensure the safety of both drivers and passengers, as well as to meet the annual greenhouse emission target from the present 704 megatonnes to 517 megatonnes of carbon dioxide equivalent by the year 2030. The proposed metallurgical research program is aimed to reduce the greenhouse emission of Canada by improving the fuel efficiency of automotive vehicles while strengthening the Canadian economy, through the development of a novel, lightweight, clean and economic third generation advanced high-strength steels (AHSS) using unconventional alloying concepts with manganese content of 8-10 wt%. Steel is not an obsolete material. Despite the development of other metallic lightweight materials for automotive parts, significant parts of the body-in-white are still and will always be made of steel in the foreseeable future. This is because of its exceptional combination of economy, strength and durability. In fact, steel industries around the world are aggressively continuing to develop the next generation AHSS. This project will be divided into four major phases. The first phase is dedicated to alloy design, stacking-fault energy (SFE) analysis, thermodynamic assessment, and casting of novel AHSS. These medium-manganese steels will be designed to achieve tensile strengths of more than 1000 MPa with elongations of 30-40%. The second phase involves heat treatment and cooling cycles of these steels to establish the equilibrium phase transitions, cooling curves and phase diagrams. The third phase involves laboratory-scale simulation of thermomechanical processing such as hot rolling and hot forging to assess the formability of these materials. The crashworthiness will be evaluated by performing high-speed deformation experiments. The fourth and final phase covers extensive microstructural characterization to accurately understand the individual effects of twinning-induced plasticity (TWIP), transformation-induced plasticity (TRIP) and precipitation hardening on the mechanical properties of medium manganese steels. At the end of the project, four new third generation AHSS will be developed and a clear processing-microstructure-property relationship will be established. The commerciality of these materials will also be evaluated. The results from this work are expected to accelerate the design and discovery of new, high-performance and energy-saving materials. Ten highly qualified personnel (HQP), which consist of five graduate (two PhDs and three MScEs) and five undergraduate students are expected to join and strengthen the Canadian automotive and manufacturing industries. They are expected to support the research and development activities and maintain the competitiveness of Canadian industries.