Impact Toughness Analysis of a High Strength Steel Hardox 450 Welded Joint

Análise da Tenacidade ao Impacto de uma Junta Soldada de um Aço de Alta Resistência Hardox 450

Abstract:

This work aims to analyze the influence of low temperature on the toughness of a high-strength steel HARDOX 450^® joints welded by the Metal Core Arc Welding (MCAW) process. Impact toughness tests (Charpy V-notch test) were performed on the 10 mm base metal (BM), weld metal (WM), and heat-affected-zone (HAZ) at temperatures of -100 °C, -80 °C, -60 °C, -20 °C, 0 °C, and 25 °C to obtain the ductile-brittle transition curve for each of these regions. Additionally, the tensile test and metallographic characterization were performed in order to complement the evaluation of the welded joint. The results of the impact tests showed higher toughness values of the base metal compared to the other two regions of the weld joint analyzed (WM and HAZ). The low toughness present in the HAZ is related to its microstructure composed of Widmanstätten ferrite and coarse grain. However, temperatures of -100 °C and -80 °C show the absorbed energy values in the three regions remarkably close to each other (between 11 J and 20 J).

Key-words:
Charpy; Ductile-brittle; MCAW