Gas tungsten arc welding (GTAW) is the primary process for precision joining of metals due to its capability for accurate control of heat input. As a close relative and modification of GTAW, plasma arc welding (PAW) has higher energy density and can penetrate thicker workpieces while maintaining the desired capability for accurate control of heat input. In order to produce quality welds consist...

The weld pool is the core of the welding process where complex welding phenomena originate. Skilled welders acquire their process feedback primarily from the weld pool. Observation and measurement of the three-dimensional weld pool surface thus play a fundamental role in understanding and future control of complex welding processes. To this end, a laser line is projected onto the weld pool surf...

This paper investigates the effects of process parameters on weld bead width of austenitic stainless steel SS-310 in tungsten inert gas welding. The four parameters namely welding current, type of gas, gas flow rate and included angle of weld plates during butt joint were varied at three levels. The DOE approach was used to design experimental conditions. Orthogonal array L9 was used for carryi...

Gas tungsten arc welding is fundamental in those industries where it is important to control the weld bead shape and its metallurgical characteristics. However, compared to the other arc welding process, the shallow penetration of the TIG welding restricts its ability to weld thick structures in a single pass (~ 2 mm for stainless steels), thus its productivity is relativity low. This is why th...

Plates of 3–5 mm in thickness were extracted from an AZ91D ingot and then butt joints of the plates were produced using tungsten inert gas (TIG) welding method. The TIG arc was also used to deposit welding beads on some of the thin plates. No cracking was found in the butt joints. However, hot cracking was always observed to propagate from the heat affected zone (HAZ) under the welding bead int...

In this research, optimization of the pulsed gas tungsten arc welding including pulse current, background current, pulse frequency and on time were investigated in welding of non-similar materials of austenitic stainless steel AISI 316L and nickel-base super alloy of Monel 400 by using ERNiCr3 filler metal. In order to obtain optimum conditions of welding the Taguchi method with the L9 array wa...

Abstract: During the last decade, the demand for natural gas has steadily increased for the prevention of environmental pollution. For this reason, many liquefied natural gas (LNG) carriers have been manufactured. Since one of the most important issues in the design of LNG carriers is to guarantee structural safety, the use of low-temperature materials is increasing. Among commonly employed low...

AbstructThis application paper addresses the control of a nonminimum-phase plant with variable large orders and delays. The process concerned is full penetration gas tungsten arc welding. Based on an analysis of accepted adaptive algorithms, the generalized predictive control algorithm presented by Clarke et al. is selected as the principal control strategy. An adaptive generalized predictive d...