In the welding project, the choice of welding wire is to ensure that the welding quality and performance of the key links. It should not only consider the type of steel being welded, but also need to take into account the quality requirements of the welded parts, construction conditions, cost and chemical composition of the wire and other factors. In this article, we will introduce in detail the various aspects to be considered when selecting welding wire, as well as the influence of the chemical composition of the wire on the welding performance.
First, the basic principles of wire selection
1. Matching steel: According to the welded structure of the steel, select the appropriate wire to ensure that the weld metal and the chemical composition and mechanical properties of the base material to match.
2. equal strength matching: for carbon steel and low alloy high-strength steel, should follow the "equal strength matching" principle, select the mechanical properties to meet the requirements of the wire. For heat-resistant steel and weathering steel, need to pay attention to the consistency of the weld metal and the chemical composition of the base material.
3. Quality requirements: according to the quality requirements of the welded parts (such as impact toughness), select the appropriate wire.
4. process conditions: consider the welding conditions, bevel shape, shielding gas mixing ratio and other process conditions, choose not only to ensure the performance of the welded joints, but also to improve welding efficiency and reduce costs of the wire.
5. Welding position: according to the site welding position, select the appropriate wire diameter and current value to ensure the smooth progress of the welding process.
Second, the characteristics and application of different types of welding wire
1. flux-cored wire: with good process performance, good weld quality, strong adaptability to steel and other advantages, suitable for a variety of steel welding, such as low carbon steel, low alloy high-strength steel, stainless steel and so on. Its shielding gas can choose CO2 or Ar+CO2.
Flux-cored wire for low-carbon steel and high-strength steel: mainly used in shipbuilding, bridges, construction, vehicle manufacturing and other fields, with many varieties and large dosage.
Flux-cored wire for stainless steel: characterized by good process performance and stable mechanical properties, it is widely used in petrochemical, pressure vessel, shipbuilding and engineering machinery industries.
Flux-cored wire for wear-resistant cladding: increase wear resistance through transition alloying elements or make the metal surface to obtain special properties, suitable for wear-resistant cladding and other occasions.
Self-protecting flux-cored wire: no need for additional protective gas or flux, suitable for field or overhead work, with high deposition efficiency, wind resistance and other advantages. However, it should be noted that the weld metal plastic, toughness is generally lower than the flux-cored wire with auxiliary shielding gas, and welding fume is larger, need to strengthen ventilation.
Third, the chemical composition of the wire on the impact of welding performance
1. Weld strength: carbon is one of the main chemical composition of the wire, the strength and hardness of the weld has a significant impact. However, too high a carbon content may reduce weldability and impact toughness. Manganese, molybdenum and other elements can improve the toughness and hardenability of the weld.
2. Weld embrittlement: Elements such as hydrogen, nitrogen, oxygen, phosphorus and sulfur may cause weld embrittlement. Therefore, in the design of the chemical composition of the wire, the content of these elements need to be strictly controlled.
3. Impact toughness: manganese, nickel and other elements have an important impact on the low temperature impact toughness of the molten metal. By adjusting the content of these elements, the impact toughness of the weld can be improved.
4. Corrosion resistance: chromium, nickel and other alloying elements can improve the corrosion resistance of the wire. These elements can reduce oxidation and corrosion in the welding process and improve the corrosion resistance and corrosion resistance of the weld.
In general, the selection and chemical composition design of welding wire is a comprehensive process that takes into account a number of factors. In order to ensure that the performance of the welded joint meets the requirements, it is necessary to select the appropriate type and size of wire according to the specific welding needs, and pay attention to the influence of the chemical composition of the wire on the welding performance. At the same time, the selection of high quality, reliable brand wire products is also the key to ensure the quality and efficiency of welding.
