TWI Industrial Member Report Summary 109/1980
By R E Dolby
Correlations between Charpy V and COD test data for deposits in C-Mn and C-Mn microalloyed steels have been sought by reviewing published and unpublished literature. The information was grouped by welding process and plate thickness and the results separated for the as-welded and postweld heat treated conditions. Correlations were found between Charpy V and COD transition temperatures and between Charpy V transition temperature and the mean and minimum COD at -10 degrees providing:
i. care was taken to match the micromechanisms of fracture in both specimen types and
ii. both tests sampled the same region of the weld deposit.
The report shows, in particular, that COD values determined for manual metal arc and flux cored wire deposits using through-thickness notched specimens machined from double V weldments are controlled by weld root Charpy properties, and in the as-welded condition are unaffected by specimen thickness in the range 25-100mms. An effect of yield strength on Charpy-COD correlations was found in the case of submerged arc weldments. The findings of this review concerning the toughness of double V weldments should not be implied as a criticism of the requirements of existing National Standards. However, the report should be of value to industry in dealing with problems of adequate fracture toughness or defect tolerance in specific applications. The report is a first attempt to produce guidance on Charpy-COD relationships and should be treated as such. The Welding Institute will continue to pursue this topic and provide further data in the future.