The Influence of Heat Input on the Formation of Fatigue Cracks for High-Strength Steels Resistant to Low Temperatures

Abstract

Welding is one of the most widely used metal joining techniques. However, improper technique and handling may lead to weld defects. Cracks that occur during the exploitation of the welded joints in places of increased stress concentration are called fatigue cracks. In our previous study, we suggested that lowering the stress concentration in the zone of the weld face may prevent surface cracks in butt-welded joints. Here, we further examined how welding heat input and external factors can be controlled to minimize the occurrence of fatigue cracks on welded joints. The fatigue cracks analyzed in this study occurred during the exploitation and are a consequence of the increased stress concentration at the toe of the weld. We performed twenty-four welding experiments comprising the following four welding conditions: torch angle, number of cover passes, length of electrode stick-out, and shielding gas (two environments were used). Stress concentration factors and heat input were determined via experimental data. The results suggested that higher heat input is associated with a lower risk of developing fatigue cracks. Thus, we concluded that fatigue cracks could be minimized by increasing the arc voltage and current while also reducing the welding speed.

Keywords

• heat input
• stress concentration factor
• arc voltage
• arc current
• welding speed