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Gas Metal Arc Welding (GMAW) is commonly used in the automotive industry for joining heavier gauge mild and High Strength Low Alloy (HSLA) uncoated steels, where it is recognized for its versatility and speed. The only constraints typically encountered relate to fatigue performance of the joint as a result of poor design or manufacturing fit-up. Advanced High Strength Steels (AHSS), now being considered for more and more applications, however, do not offer the same ease of welding and process control is significantly more critical. They differ from mild steels in chemical composition and thermal processing, resulting in a different microstructure; designed with a richer metallurgy to have higher strength at equivalent thickness. As a result, the sensitivity to heat input is greater and the process window in which acceptable welds can be achieved is narrower.

There has been a substantial increase in the use of advanced high strength steel 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 new safety and fuel economy regulations. These new materials have significant manufacturing challenges, particularly for welding and stamping. Proper understanding of the weldability of these materials is critical for successful application in future vehicle programs. This paper presents our production experience in use of DP600. Development work on the effect of weld tips on button size, and shrinkage voids due to different welding variables is discussed. The paper also provides recommendations from the current experimental knowledge base for applications on higher grades of steel (DP780 and beyond).

Gas Metal Arc Welding (GMAW) is used in the automotive industry, for joining heavier gauge mild and HSLA steels, where it is recognized for its versatility and speed. The only constraints typically encountered relate to fatigue performance of the joint as a result of poor design or manufacturing fit-up. Advanced High Strength Steels, however, do not offer the same ease of welding, and process control is significantly more critical. The process window represents the range of acceptable process parameters, primarily heat inputs, to achieve an acceptable weld; which is a measure of the robustness of the process. AHSS differ from mild steels in chemical composition and thermal processing, resulting in a different microstructure; designed with a richer chemistry to have higher strength at equivalent thickness compared to mild steels. As a result, the sensitivity to heat input is greater and AHSS has a narrower process window in which acceptable welds can be achieved.