2010 Volume 28 Issue 1 Pages 97-107
It is well known that weld residual stress and distortion should be controlled appropriately for structural integrity. Recently, it has become much more necessary to control weld distortion for highly improving manufacturing efficiency.
Various studies on control of weld distortion had been conducted based on clarification of influential dominant factors for that. The influential dominant factors had been studied from a viewpoint of temperature distribution in plate thickness section. Without considering moving of weld heat source, the temperature distribution is controlled by weld heat input (Qnet) per weld length. Angular distortion, which is controlled by temperature distribution along direction of plate thickness (h), is controlled by heat input parameter (Qnet/h2). However, it has been recently known that the conventional results cannot be applied to all welding processes because such processes are becoming more diversified. It is significant for more accurate control of angular distortion to investigate once again the relationship between the heat input parameter and angular distortion.
In this study, series experiments on the relationship between heat input parameter and angular distortion is performed. The effects of welding current and welding speed are investigated individually in both TIG and MAG welding. The difference between these welding methods is also investigated. Based on the result, the effects of them are discussed in relation to temperature distribution during welding. It is considered that angular distortion is affected by temperature distribution not only in plate thickness section but also along welding direction. So, angular distortion is not always controlled by only the conventional heat input parameter because the heat input parameter is proposed as the influential dominant factor for temperature distribution in plate thickness section. It is concluded that generation characteristics of inherent strain should be considered in relation to three dimensional temperature distributions during welding for more accurate control of angular distortion.