Microstructural Features Controlling the onset of Crack Formation during the Bending of S700 and S960 High Strength hot rolled steels

塔塔钢铁公司目前正在开发一系列热轧高强钢，其最低屈服强度为700、900、960和1100MPa，用于起重和挖掘领域。这些等级通常需要通过简单的弯曲操作进行冷成型，以生产起重机臂架等最终部件。在其中一些牌号的开发过程中，特别是S700和S960牌号，虽然强度和韧性之间的平衡非常好，但这些钢的可弯曲性很差和/或不一致。这种不良的弯曲性能现在限制了潜在供应的市场，因此真正需要首先了解控制可弯曲性的因素，然后提高可弯曲性。谢菲尔德大学提出的工作将使用高分辨率数字图像相关和微网格等技术研究厚的高强度钢的弯曲行为，并研究弯曲过程中第二相颗粒的损伤演变。最终目标是设计出在弯曲过程中更能抵抗裂纹形成的微结构。确定在高强度厚热轧带材弯曲过程中控制裂纹形成的显微组织特征和应力-应变行为。对弯曲过程进行高分辨率的局部应变测量，验证弯曲有限元模型。这项工作符合EPSRC的研究目标，因为它将通过保持英国在材料和钢铁研究方面的世界领先地位来提高能力。该职位将通过在专业环境中领导塔塔钢铁的工作，使领导技能得到发展。塔塔钢铁利用这项研究开发新产品，将加速这种影响。塔塔钢铁公司正在这个项目上进行合作。

Tata steel is currently developing a range of thick, hot rolled high strength steels with minimum yield strengths of 700, 900, 960 and 1100MPa for use: in the lifting and excavating sector. These grades often require cold forming via simple bending operations to produce final components such as crane booms. During the development of some of these grades, especially the S700 and S960 grades, whist the balance between strength and toughness has been excellent, the bendability of these steels has been poor and/or inconsistent. This poor bending behaviour is now limiting the markets which can be potentially supplied, and so there is a real need to firstly understand the factors controlling bendability, and then to improve bendability. The proposed work at Sheffield University wilI study the bending behaviour of thick, high strength steels using techniques such as high resolution digital image correlation and micro-gridding, and also study damage evolution at second phase particles during bending. The ultimate goal is to design microstructures which are more resistant to crack formation during bending.To determine the microstructural features and stress-strain behaviour which control the onset of crack formation during the bending of high strength, thick, hot rolled strip. To make high resolution local strain measurements during bending to validate FE models of bending.This work alines with the EPSRC's research aims as it will improve capability by keeping the UK as a world leader in material and steel research. This role will enable the development of leadership skills by leading the work with Tata steel in the professional environment. The impact will be accelerated by Tata Steel using the research to develop new products.Tata steel are collaborating on this project.