| Abstract Scope |
Controlling weld characteristics has conventionally employed a trial-and-error approach to establish acceptable ranges in variability for process parameters and composition limits. This approach has limited predictive capability for anticipating how changes in either composition or process parameters will quantitatively impact weld characteristics. Composition limits set by industrial standards encompass broad ranges of material properties that are not necessarily representative of material that has been welded in literature. A survey of reported alloy compositions was conducted to establish a representative composition range for laser welded 304L austenitic stainless-steel alloys. The compositions found in this survey have been used with industrial thermophysical modeling software to develop property ranges and models of property dependence on composition. The property ranges have been used with established numerical models of heat transfer and fluid flow for laser welding to establish weld characteristic ranges for composition and property ranges found in the literature survey. A one-at-a-time sensitivity analysis of composition dependent material properties was used to establish the relative importance of alloying elements on material properties pertinent to laser welding numerical models. A one-at-a-time sensitivity analysis approach was used for the material properties and processing parameters with the welding model to establish a hierarchy of contributions to variability in weld characteristics. The material properties found to be of most importance to weld variability are enthalpy of the solid and liquid, thermal conductivity of the liquid, heat capacity of the solid, solidus, and liquidus. The composition changes that strongly influence these properties are changes in chromium, nickel, copper, and phosphorous amount. The process parameters with the strongest influence on weld characteristics are changes in defocus distance and laser beam diameter at focal point. Quantifying these relationships between the composition, material parameters, process parameters, and weld characteristics will permit for more robust welding process quality control requirements. |