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There has been a substantial increase in the use of advanced high strength steel (AHSS) in automotive structures in the last few years. The usage of these materials is projected to grow significantly in the next 5-10 years with the introduction of new safety and fuel economy regulations. AHSS are gaining popularity due to their superior mechanical properties and use in parts for weight savings potential, as compared to mild steels. These new materials pose significant manufacturing challenges, particularly for welding and stamping. Proper understanding of the weldability of these materials is critical for successful application on future vehicle programs. Due to the high strength nature of AHSS materials, higher weld forces and longer weld times are often needed to weld these advanced strength steels.

In an attempt to develop gas-metal arc-welded (GMAW) sheet steel coupons with tightly controlled weld geometry for fatigue testing, it was discovered that the very slight changes in welding process parameters strongly influence the weld geometry. The extent of fusion zone, horizontal and vertical leg lengths, and depth of penetration were considered to define the weld geometry. In order to elucidate the sensitivity of weld geometry to process parameters, a study was conducted on welding of various types of specimens. The paper reports the results of variations in weld geometry with small changes in process parameters. In addition, through several examples, it is demonstrated that variability in the weld geometry is unavoidable even with very tight weld process control.