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How to Choose Welding Wire for Steel Structure Welding

The selection of welding wire should be comprehensively considered based on the type of steel being welded, the quality requirements of the welded components, welding construction conditions (plate thickness, groove shape, welding position, welding conditions, post weld heat treatment and welding operation, etc.), cost, and other factors.


The order to consider when selecting welding wires is as follows

1. Select welding wire based on the steel grade of the welded structure


For carbon steel and low alloy high-strength steel, the principle of "equal strength matching" is mainly followed to select welding wires that meet the mechanical performance requirements. For heat-resistant steel and weathering steel, the main focus is on considering the consistency or similarity of the chemical composition between the weld metal and the base material to meet the requirements for heat resistance and corrosion resistance.


2. According to the quality requirements of the welded components (especially impact toughness)


The selection of welding wire is related to process conditions such as welding conditions, groove shape, and shielding gas mixture ratio. It is necessary to select welding materials that achieve maximum welding efficiency and reduce welding costs while ensuring the performance of the welded joint.


3. According to the on-site welding position


Select the welding wire diameter corresponding to the plate thickness of the welded part, determine the current value used, refer to the product introduction materials and usage experience of each production plant, and select the welding wire grade suitable for the welding position and current usage.


The welding process performance includes arc stability, size and quantity of splashing particles, slag removal ability, weld appearance and shape, etc. For the welding of carbon steel and low alloy steel (especially semi-automatic welding), the welding method and welding materials are mainly selected based on the welding process performance. The comparison of welding process performance between gas shielded welding using solid core welding wire and flux core welding wire is shown in the chart:


Selection of Flux Cored Welding Wire

The welding of flux cored wire has advantages such as good process performance, good weld quality, and strong adaptability to steel, and has broad application prospects. Flux cored welding wire can be used to weld various types of steel structures, including low-carbon steel, low alloy high-strength steel, low-temperature steel, heat-resistant steel, stainless steel, and wear-resistant overlay welding. The protective gases used include CO2 and Ar+CO2, with the former used for ordinary structures and the latter for important structures. Flux cored welding wire is suitable for automatic or semi-automatic welding, with both DC and AC currents available.


1. Low carbon steel and high-strength steel flux cored welding wire


There are many types and large quantities of low carbon steel and high-strength steel flux cored welding wires, most of which are titanium slag systems with good welding processability and high welding productivity. They are mainly used in shipbuilding, bridges, construction, vehicle manufacturing and other departments. Low carbon steel and low alloy high-strength steel have a wide variety of flux cored welding wires. From the perspective of weld strength levels, flux cored welding wires of 490MPa and 590MPa levels are widely applicable; From a performance perspective, some focus on process performance, some on weld mechanics and crack resistance, some are suitable for all position welding including downward vertical welding, and some are specifically designed for fillet welding.


2. Stainless steel flux cored welding wire


Stainless steel flux cored welding wire has the characteristics of good process performance, stable mechanical properties, and high production efficiency. In recent years, it has been applied in industries such as petrochemicals, pressure vessels, shipbuilding, and engineering machinery abroad. At present, there are more than 20 types of stainless steel flux cored welding wires, in addition to chromium nickel stainless steel flux cored welding wires, there are also chromium stainless steel flux cored welding wires. The welding wire has diameters of 0.8mm, 1.2mm, 1.6mm, etc., which can meet the welding needs of stainless steel thin plates, medium plates, and thick plates. The protective gas used is mostly CO2, and a mixture of Ar+(20% -50%) CO2 can also be used.


3. Wear resistant overlay welding flux cored wire


In order to increase wear resistance or achieve certain special properties on the metal surface, it is necessary to transition a certain amount of alloy elements from the welding wire. With the emergence of flux cored welding wire, these alloy elements can be added to the flux core, and the processing and manufacturing are convenient. Therefore, using flux cored welding wire for submerged arc welding of wear-resistant surfaces is a common method and has been widely used. In addition, by adding alloying elements to the sintered flux, a corresponding composition of the overlay layer can also be obtained after surfacing. When combined with solid or flux cored welding wires, it can meet different surfacing requirements.


Self Protective Flux Cored Welding Wire

Self shielded welding wire refers to a welding wire that can be used for arc welding without the need for additional protective gas or flux, in order to obtain qualified welds. Self protective flux cored wire is a type of welding wire that places powder and metal powder used for slag making, gas making, and deoxygenation into the steel sheet. During welding, the powder is transformed into slag and gas under the action of the arc, providing slag making and gas making protection without the need for additional gas protection.


The deposition efficiency of self-protection flux cored welding wire is significantly higher than that of welding rod, and the flexibility and wind resistance of field welding are better than other gas shielded welding. It can usually be welded under four levels of wind force. Because it does not require protective gas and is suitable for outdoor or high-altitude operations, it is often used on installation sites and construction sites.


The weld metal plasticity and toughness of self-protection welding wire are generally lower than those of flux cored welding wire with auxiliary shielding gas. Self protective welding wire is currently mainly used for welding structures of low-carbon steel. In addition, there is a large amount of smoke and dust during the application of self-protection welding wire. When working in narrow spaces, it is important to strengthen ventilation and exchange of air.


The selection of welding wire is so important that in order to achieve the desired welding effect, it is necessary to choose suitable and high-quality brand welding wire.


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