Investigations of the influence of titanium addition to the base material on toughness properties of the HAZ

Without taking precautions on the material side the application of fully mechanized welding techniques with high heat inputs into the base metal can lead to undesirable grain growth and unfavourable toughness values in the HAZ. The aim of the investigations of four fine grained steels (FeE 355) with varied contents of titanium and nitrogen and one steel without titanium addition was to study different states of precipitation in the steels, the change after a welding simulation treatment and the comparison with real weldments. The results have shown that in titanium microalloyed steels the increase of the austenitic grain size is clearly lower than in steels without titanium addition. They keep their favourable toughness properties even after welding processes with high heat inputs. The toughness values of the SA weldings are higher than the values of the simulated specimens.