Load‐bearing capacity of pre‐strained high strength steel up to S960 – Component scale notched tensile tests

ce/papers, vol. 9, pp. 359–364

Abstract

Abstract Plastic pre‐strain can significantly influence the load‐bearing capacity of steel components, especially for high‐strength steels. While the effects of such cold‐forming processes are well understood for conventional structural steels, limited knowledge exists for high‐strength steels up to grade S960, which are increasingly used due to their favourable strength‐to‐weight ratio. These steels exhibit distinct mechanical behaviour characterized by a low yield strength ratio close to 1.0, which promotes early strain localization and necking. Consequently, pre‐straining may considerably affect both ductility and structural performance, especially in the ductile to brittle transition‐region. This study presents experimental investigations on cold‐formed high‐strength steel S960M in comparison to conventional steel S355JR in the ductile to brittle transition‐region. The primary aim is to quantify the influence of different levels of plastic pre‐strain on the toughness and structural performance at temperatures ranging from room temperature down to ‐150°C. The results demonstrate a clear correlation between increasing plastic pre‐strain and a shift of the ductile‐to‐brittle transition to higher temperatures for both, laboratory CHARPY‐tests as well as component tensile tests. While for 11 of 12 investigated pre‐strained components an increase in load‐bearing capacity due to hardening effects of the pre‐straining compared to the as delivered state was determined, one S960M specimen with 6 % pre‐strain, failed with lower maximum net‐section resistance. The findings underline the need for refined assessment models for pre‐strained high‐strength steels to improve the reliability of structural applications in demanding environments.

Authors 3

1. Mirco Meissner corresponding Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University Aachen Germany

2. Helen Bartsch Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University Aachen Germany

3. Markus Feldmann Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University Aachen Germany