Performance criteria for cold formed structural steels
A joint programme of work was carried out by Corus, IEHK, Labein and University of Cantabria to establish the effect of cold deformation and hole punching on the performance of structural steels with yield strengths up to 890 MPa. The principal objective of the project was to quantify the effects of these downstream processes on structural integrity and to provide guidelines for optimising fracture and fatigue performance. Material was subjected to various downstream processes and the shift in properties, mainly tensile, Charpy impact energy and fracture toughness, associated with the strains imparted by these processes established. The fracture and fatigue properties of punched and drilled holes were also assessed. Plates up to 890 strength level were successfully formed in a press brake and those up to 690 strength were successfully punched. Finite element models of both processes were developed, incorporating a damage criterion with a coupled model for the punching process. Regression analysis was used to derive factors for estimating property shifts as a function of level of strain from cold forming operations. Application of these shifts using structural integrity assessment methods showed them to be largely conservative. Comparisons between Eurocode 3 service temperature predictions and cold formed wide plate test results showed that largely safe predictions were obtained when using these estimates of property shifts. Fatigue tests on punched holes demonstrated that a reduced S-N class was appropriate for holes formed in this way as compared to their drilled equivalents. Orientation had a major effect on results due to the nature of the microstructural damage around the hole. Fracture tests demonstrated that punched holes have adequate strain capacity for most design situations. While the processes of cold forming and punching can lead to reduction in performance in some cases, in most conventional design situations this reduction is not of concern.
Bibliographic Reference: EUR 22056 EN (2006), 241 pp. Euro: 35
Availability: Katalogue Number: KI-NA-22056-EN-S The paper version can be ordered online and the PDF version downloaded at: http://bookshop.europa.eu
ISBN: ISBN: 92-894-5042-8
Record Number: 200719317 / Last updated on: 2007-07-10
Original language: en
Available languages: en