Computer modeling of arc welds to predict effects of critical variables on weld penetration

摘要

In recent years, there have been several attempts to study the effect of critical variables on welding by computational modeling. It is widely recognized that temperature distributions and weld pool shapes are keys to quality weldments. It would be very useful to obtain relevant information about the thermal cycle experienced by the weld metal, the size and shape of the weld pool, and the local solidification rates, temperature distributions in the heat-affected zone (HAZ), and associated phase transformations. The solution of moving boundary problems, such as weld pool fluid flow and heat transfer, that involve melting and/or solidification is inherently difficult because the location of the solid-liquid interface is not known a priori and must be obtained as a part of the solution. Because of non-linearity of the governing equations, exact analytical solutions can be obtained only for a limited number of idealized cases. Therefore, considerable interest has been directed toward the use of numerical methods to obtain time-dependant solutions for theoretical models that describe the welding process. Numerical methods can be employed to predict the transient development of the weld pool as an integral part of the overall heat transfer conditions. The structure of the model allows each phenomenon to be addressed individually, thereby gaining more insight into their competing interactions. 19 refs., 6 figs., 1 tab.