Overview of Shielding Gases
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Shielding gases. The right gas working for you.

The right shielding gas does make a difference. To most users a shielding gas is just there to protect the welding from the effects of ­ xygen and nitrogen in the atmosphere. While this is a o key function of the shielding gas other benefits can be achieved by making the correct product choice. Some are metallurgical such as improved corrosion resistance, some are mechanical such as tougher weld metal, some are financial such as reduced weld cost or improved productivity. Understanding what shielding gases are capable of delivering to your ­ usiness can bring about considerable financial...

Choosing the right shielding gas for your needs. Weld metal properties The careful combinations of different gases, often tailored to specific materials, can improve the performance in any welding situation by lower manufacturing costs through: Although weld metal properties are primarily controlled by the consumable composition, the shielding gas can directly influence the strength, ductility, toughness and corrosion resistance of a weld. • improving the weld metal properties, such as strength, corrosion r ­ esistance and toughness • changing the weld bead shape and size • improving the...

The addition of helium to the shielding gas results in a hotter welding arc than that produced from pure argon. Carbon dioxide Weld shape and quality Although shielding gases with lower levels of oxygen and/or carbon dioxide usually result in weld metal having higher mechanical ­ roperties, p these welds can suffer from greater numbers of fusion defects than those made from gases with higher oxidation potentials. Shielding gases with low oxidation potentials produce weld beads with a very narrow wineglass or finger like bead profile. However, adding carbon dioxide to the shielding gas makes...

Impact values at –20  (joules) °C 0.040 CORGON 5S2 % Carbon in weld metal Maximum limit in stainless steel Carbon dioxide Operational performance There are many ways in which a shielding gas can improve welding process performance. For example, VARIGON H5 uses the addition of hydrogen to argon for TIG welding austenitic stainless steel to produce a more fluid arc, which allows welding speeds to be significantly increased. To get the best performance out of any welding product, whether the wire, power source or shielding gas, the skill and knowledge of the o ­ perator is always important....

The right shielding gas from Linde. Choosing the right shielding gas is important for your business, ­ arking m the transformation from cost to profit. Linde has put together a series of material related guides to help you make the right selection for each of your welding applications: • Shielding gases for carbon and low alloy steels • Shielding gases for stainless steels • Shielding gases for non-ferrous materials By knowing what is the most important feature you want from your shielding gas – for example welding speed, lower defect levels, better mechanical properties – you can choose...

Making the right choice can really save you money. A high percentage of manufacturers only measure the cost of welding either by the man hours to produce a component or in terms of the c ­ omponent costs of the gas and wire used over a period of time. While both these measures will give a rough measure as to the cost of a weld, they do not tell the whole story. In most literature on the topic of weld costing four elements are mentioned: • • • • Gas Wire Labour Power These four elements are the easiest to quantify but do not reveal the full cost. Irrespective of the material being welded the...

Typical cost breakdown for MAG welding carbon steel Typical cost breakdown for MAG welding stainless steel Power 2 % Labour 25 % Wire 20 % For example, in carbon steel MAG welding every 8.5 grams of spatter ­ generated is equivalent to 1 metre of 1.2 mm diameter ­ elding wire w being thrown on the floor. At high welding currents using carbon dioxide, over 17 grams of spatter is generated for every metre of weld completed. In the worst case if the component cannot be repaired and has to be scrapped, there is the additional cost of the raw material and any p ­ re-welding work carried out,...

Frequently asked questions about shielding gases. 1. Why am I getting holes in my welds? 2. Why can I not use pure argon for MAG welding steels? Holes (porosity) is usually caused by gas trapped inside the cooling weld metal. While gases such as nitrogen are one of the main causes of porosity, other sources such as water, oil and grease on the material can be as much of a problem. The main causes of porosity are: While it is possible to MAG weld steels with pure argon, the arc produced is very unstable and erratic, and the resultant weld will have a lot of spatter and an unsatisfactory...

4. Why do I get cracks in my stainless steel welding? 5. hat causes the “sooty” deposit when welding ­ luminium? W a There are two main types of cracking in stainless steels: “hot cracking” and “cold cracking”. This “sooty” deposit is not soot (carbon) at all, but a form of aluminium oxide. Hot cracking, correctly termed “solidification cracking”, tends to be a problem in austenitic stainless steels. It is called “hot cracking” as it tends to occur immediately after welding while the weld is still hot. Weld metal solidification cracking is more likely in fully austenitic s ­ tructures which...

Getting ahead through innovation. With its innovative concepts, Linde is playing a pioneering role in the global market. As a technology leader, it is our task to constantly raise the bar. Traditionally driven by entrepreneurship, we are working steadily on new high-quality products and innovative processes. ­ Linde offers more. We create added value, clearly discernible competitive advantages, and greater profitability. Each concept is tailored specifically to meet our customers’ requirements – offering standardised as well as customised solutions. This applies to all industries and all...