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

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.