TWI Industrial Member Report Summary 532/1995
A J Kinsey
As a result of recent steelmaking trends towards low hardenability thermomechanically, controlled processed (TMCP) steels and the development of lower hydrogen potential welding consumables, the possibility of welding even thick section structural steels without preheat is becoming more and more feasible. Current guidelines for very low hydrogen potential consumables are largely based on cracking data obtained mostly on high carbon equivalent steels. In the present work, controlled thermal severity (CTS) tests were conducted on a range of 50mm thick steels which were representative of old and new carbon equivalents. All welding was performed with consumables which conformed to scale D hydrogen level i.e. <5ml H2/100g deposited weld metal. The data generated were compared to the guidelines given by TWI nomograms so that the validity (or shortcomings) in the present system could be assessed. Even when BS5135 indicates preheat is not required some fabricators use a
To define the limits within which preheat can be safely avoided when welding new steels with recently developed, low hydrogen consumables.