TWI Industrial Member Report Summary 938/2009
L S Smith
The performance of steel weldments often depends upon the characteristics of the heat affected zone (HAZ) and, in particular, the grain-coarsened HAZ (GCHAZ). This zone of the weldment poses significant challenges for modelling, since thermal cycle and grain growth must be successfully predicted before phase transformation modelling during cooling can be attempted. Previous work at TWI[i,ii] produced software for the prediction of GCHAZ (Microsim) and weld metal microstructure in single pass arc welds. The last year of development of this software benefited from TWI's involvement in the early stages of a collaborative ECSC programme, partnered with Corus, CEIT, Arcelor and CSM. However, the subsequent years of the ECSC programme have produced software that exceeds the capabilities of the original 'Microsim' software, drawing upon the expertise of the partners.
The ECSC programme covered five main themes (and one integration task) aimed at modelling GCHAZ microstructure and performance in plain and microalloyed C-Mn steel power beam and single and multipass arc weldments:
- Prediction of thermal profiles, led by CSM.
- GCHAZ single pass microstructure prediction, led by Corus.
- Prediction of martensite-austenite (MA) constituent in multipass welds, led by Arcelor.
- Effect of postweld heat treatment (PWHT), led by TWI.
- Prediction of toughness, hardness and strength, led by CEIT.
- Drawing together of the disparate models into one single integrated piece of computer software (HAZMET), led by TWI.
The origin of the various modelling methods employed in each of the themes described above and details of their use and validation are given in the final ECSC report[iii]. The present report describes the HAZMET software that was produced by TWI to integrate the modelling code of CSM, Corus, TWI and CEIT. Arcelor developed it own stand-alone software for the prediction of MA constituent in multipass welds, and thus is not included in HAZMET.
Integrate the computer code produced by the collaborative programme partners into a coherent piece of software capable of running on a conventional computer platform.