Evaluation of Control Techniques for Dip Transfer Gas Metal Arc Welding

Dip transfer gas metal arc welding (GMAW) is used extensively for high productivity welding of thin sheet steel, and is also useful for positional welding of thicker section steels. Unfortunately in the past, the process has gained a reputation for fusion defects, which becomes more apparent when welding traditionally difficult materials such as coated steels. This reputation can be attributed in some instances to the method of control used and the changeable nature of variables crucial to controlling heat transfer during the welding process. The paper examines the relationship between weld fusion, heat input and current for coated steel welding applications and evaluates the effectiveness of two common control techniques when exposed to variation in welding torch angle. It is concluded that current control produces more consistent weld penetration and fusion area, irrespective of variations in welding torch angle or whether the base sheet steel is Zn or Zn-Al alloy coated.