Shielding gas

About: Shielding gas is a research topic. Over the lifetime, 6697 publications have been published within this topic receiving 58668 citations.

Effects of oxygen contamination in the argon shielding gas in laser welding of commercially pure titanium thin sheet

Abstract: This work studied the effects of oxygen contamination in the argon shielding gases on weld microstructures and properties during laser welding of commercially pure titanium thin sheets. The experimental results, mainly analyzed by optical and scanning electron microscopy and mechanical testing, have indicated correlations between weld surface colour, weld microstructure and mechanical properties (strength, ductility, hardness). As the oxygen content increased, the weld surface colour changed from silver, straw to blue while the surface hardness continued to increase. On the other hand, with the increasing of oxygen content, the weld strength increased first and then decreased because the microstructure changed from mainly serrated alpha in welds made with pure argon shielding gas to mainly acicular and platelet alpha. Practical guidelines are also discussed, based on the study, to deal with shielding deficiencies in laser welding of titanium.

Arc welding torch

Abstract: An arc welding torch for robotic applications having sensing capabilities to provide intelligent diagnostics monitoring of the welding process in real time. A plurality of modular sensors are integrated with the torch to provide real-time monitoring of wire speed, arc voltage, gas flow, seam-tracking, welding current temperature and contact tip wear. The torch includes a contact tip wear sensor for sensing the wearing of the tip during the welding process. The shielding gas flow is measured by a gas flow sensor mounted between the main housing and the gooseneck. A seam-tracking sensor is mounted on the outside of the housing to detect the position of the seam to be welded. The speed of the consumable electrode is measured by a wire speed sensor module. To ensure that operating temperatures of components near the arc region are within predetermined ranges for optimum performance of the torch, temperature sensors are mounted on the torch. An arc voltage sensor is located in the housing of the torch to provide a more accurate measurement of the arc voltage near the arc region. Lastly, a current sensor is located between the main housing and the gooseneck to measure the current flow through the torch. All of the above sensors may be operatively connected to a weld controller which analyze the information received from each sensor to maintain an optimum welding process.

Weldability of High Nitrogen Stainless Steel

Abstract: The purpose of this paper is to give a short survey of nitrogen influence on stainless steel welds. The review are covers: the levels of nitrogen in weld metal, the influence of nitrogen on stainless steel weld metal characteristics such as weld defects, corrosion resistance and mechanical properties. High nitrogen steel welding must consider the risk of nitrogen escape from the weld pool. Avoiding nitrogen losses may be accomplished by controlling shielding gas, welding parameters and compositions of filler metal. The increase of nitrogen in the weld metal decreases in the δ ferrite content. The reduction of δ ferrite in austenitic weld metals will result in an increase in the solidification cracking susceptibility. However, the role of nitrogen in affecting the solidification cracking susceptibility of fully austenitic weld metals is unclear. Nitrogen addition increases the pitting corrosion resistance in weld metals whereas decreases resistance to stress corrosion cracking because of δ ferrite reduction. Nitrogen also improves mechanical properties in weld metals. However, the presence of nitrides may be detrimental to the mechanical properties in stainless steel welds.

Welding Duplex Stainless Steels — A Review Of Current Recommendations

Abstract: A steel will not become widely accepted and used unless it can be successfully welded without too many limitations. Contemporary duplex stainless steel grades fulfil these requirements with some grade dependent differences. The duplex stainless steel family has, during the last decade, been extended with new lean grades and recently also highly-alloyed hyperduplex grades. Most welding recommendations are very similar to those of the 1990’s. However, the introduction of new grades and the increased use of newer welding methods has somewhat changed the perception of what is possible. This paper discusses the state-of-the-art and trends in welding of duplex stainless steels. It is based on input from the worldwide welding community, including users and producers of steel and welding consumables as well as literature. In most cases, there is consensus on recommendations but variations reflecting differences in practices exist in particular for newer steel grades where limits in e.g. allowable energy inputs are less well documented.