Fracture toughness of 80mm thick electroslag welded joints with COD approach application

Abstract

The paper deals with searching for criteria for the mechanical properties estimation of thick walled electroslag welded joints with an aim to find out whether the COD approach would be reliable for the differentiation of brittle fracture resistance. Three types of C-Mn steels modified by titanium, vanadium and molybdenum respectively with yield point of about 40 kp/mm 2, applied usually for pressure vessels and bridge constructions were used in the experimental work. The welded joints were tested in as-welded, stress relieved, and normalized and tempered conditions respectively. It was stated that the COD approach distinguishes quite well the above mentioned variants of the heat treatment of welded joints and base materials apart from the necessity of some precision of testing procedure and evaluation of test results. The adventage not under discussion of COD approach in comparison to classic methods lies in the interpretation of brittle fracture resistance by the parameter of the defect size particularly for the conditions where no valid K IC values are obtained.