Investigation of the composite strength of hybrid steel-steel semi-finished products manufactured by laser beam welding and friction welding

Abstract

An ever-increasing demand for more effective products with lower weight, more compact design and extended functionality has led to the use of material combinations with locally adapted properties instead of mono-materials. The Collaborative Research Centre (CRC) 1153 "Tailored Forming" at LUH addresses this topic with the aim to develop hybrid bulk-metal components on the basis of a new, tailored production process using joined semi-finished products. In contrast to existing manufacturing processes for hybrid bulk-metal components where the joining takes place during the forming process or at the end of the production chain, CRC 1153 uses tailor-made semi-finished products which are joined before the forming process. This contribution focuses on the production of hybrid semi-finished products from a steel-steel (C22.8 and 41Cr4) material combination by means of laser beam as well as friction welding. The effects of additional ultrasonic coupling into the weld-pool are presented for laser beam joining and a positive effect on the weld pool was observed. Furthermore, the resulting properties of the joining zone are investigated by uniaxial tensile tests at room temperature and metallographic analyses of the respective manufacturing processes. The friction welding proved to be a very robust process for the production of semi-finished steel-steel products.