Computational analysis of the yield stress of ultra-high strength all-weld metals

Abstract

Lightweight constructions providing a high yield stress play a crucial role in transportation systems and steel constructions optimized for low energy consumption. For the fabrication of such components, the development of matching welding consumables is an essential task. In this investigation, the aim is to understand the influence of different alloying elements on the strength of all-weld metal samples of ultra-high strength filler metals with a yield strength of 1100 MPa. In the end, this should provide insight into the operating mechanisms providing the desired strength and make it possible to predict the expected yield stress with reasonable accuracy. Apart from precipitation and solid solution strengthening, special attention is paid to the contributions of dislocation hardening and grain boundary strengthening, since these are expected to be the major contributors to the overall strength in a predominantly martensitic structure. In order to apply those classical strengthening mechanisms to the specific microstructure of martensite, additional considerations have to be made concerning the effective grain size and initial dislocation density used for calculation. Finally, the developed model is tested and the results are compared with over 90 actually produced and measured alloys.