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

塔塔钢铁目前正在开发一系列最低屈服强度为700、900、960和1100 MPa的厚热轧高强度钢，用于用途：起重和挖掘行业。这些等级通常需要通过简单的弯曲操作进行冷成型，以生产最终部件，例如起重机吊杆。在这些钢的某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已经很好，但这些钢的弯曲性却很差和/或不一致。这种差的弯曲性能现在限制了可以潜在供应的市场，因此存在真实的需要首先了解控制可弯曲性的因素，然后改善可弯曲性。谢菲尔德大学的拟议工作将利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粒子的损伤演化。最终目标是设计出在弯曲过程中更能抵抗裂纹形成的显微组织。确定在高强度、厚热轧带钢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。在弯曲过程中进行高分辨率的局部应变测量，以验证弯曲的有限元模型。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材研究方面的世界领先地位来提高能力。这个角色将通过在专业环境中领导塔塔钢铁的工作来发展领导技能。塔塔钢铁公司利用这项研究开发新产品将加速这一影响。塔塔钢铁公司正在合作这一项目。

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.