Effects of welding parameters on tensile strength of weld metal in flux cored arc welding

Effects of welding parameters such as welding current, voltage and travel speed on the tensile strength of weld metal in flux cored arc welding were studied. The results were interpreted in terms of chemical composition and microstructural change in the weld metal. When heat input was increased to 2.1 kJ mm(-1) by increasing welding current, the tensile strength of the weld metal increased. However, the tensile strength of the weld metal decreased when heat input was increased from 2.1 to 4.5 kJ mm(-1) by reducing travel speed or by increasing voltage. It showed that when heat input is higher than 2.1 kJ mm(-1) the decrease in tensile strength was related with the microstructural change. However, when heat input is lower than 2.1 kJ mm(-1) the increase in tensile strength was hardly related with the microstructural change. As Pcm value in the weld metal increases in the heat input up to 2.1 kJ mm(-1), it is believed that Pcm value has more powerful effect than microstructure in the heat input range. It showed that variation of the welding parameter resulted in different recoveries of the alloying elements in the wire. The recoveries increased with an increase in welding current and/or travel speed, but they decreased with an increase in voltage. The effects of welding parameters on the recoveries were rationalised with the time available for the reaction with oxygen during welding.