Selection of Solid Welding Wire

01丨Welding Wire for Submerged Arc Welding

In the process of submerged arc welding, the welding wire serves the dual purpose of filling metal and introducing alloying elements into the weld while participating in metallurgical reactions that protect and treat the weld metal.

1）Selection of Welding Wire for Low Carbon Steel and Low Alloy Steel:

During submerged arc welding of low carbon steel and low alloy steel, the following three types of welding wires are commonly employed:

A. Low manganese welding wire (e.g., H08A): Typically used in conjunction with high manganese flux for welding low carbon steel and low-strength low alloy steel.

B. Medium manganese welding wire (e.g., H08MnA, H10MnS): Mainly utilized for welding low alloy steel and can also be used with low manganese flux for welding low carbon steel.

C. High manganese welding wire (e.g., H10Mn2, H08Mn2Si): Employed in welding low alloy steel.

2) Selection of Welding Wire for High-Strength Steel:

This category of welding wire contains over 1% manganese and 0.3% to 0.8% molybdenum, such as H08MnMoA and H08Mn2MoA, suitable for welding high-strength low alloy steel. Depending on the composition and performance requirements of high-strength steel, elements such as Ni, Cr, V, and Re can be added to the welding wire to enhance weld metal properties. Welds with a tensile strength of 590MPa often use MN-MO series welding wires like H08MNMOA.

3) Selection of Stainless Steel Welding Wire:

The selection of welding wire for welding stainless steel should closely match the composition of the base stainless steel. For chromium stainless steel, HoCr14, H1Cr13, and H1Cr17 welding wires are employed. When welding chromium-nickel stainless steel, wires like H0Cr19Ni9, HoCr19Ni9, and HoCr19Ni9Ti are used. For welding ultra-low carbon stainless steel, corresponding ultra-low carbon welding wires, such as HOOCr19Ni9, are employed. Flux can be either smelting or sintering, with a preference for low-oxidation flux to minimize alloy element loss. While foreign countries predominantly use sintering flux for stainless steel welding, China still primarily employs smelting flux, though research and promotion of sintering flux are ongoing.

02丨Welding Wire for Gas Shielded Welding

Gas-shielded welding includes inert gas-shielded welding (TIG and MIG welding), active gas-shielded welding (MAG welding), and self-shielded welding. In TIG welding, pure Ar gas is typically used, while MIG welding generally employs Ar+2%O2 or Ar+5%CO2 gas mixtures. MAG welding mainly relies on CO2 gas. To improve the performance of CO2 welding, CO2+Ar or CO2+Ar+O2 gas mixtures can be used, along with flux-cored wires.

1) TIG Welding Wire:

In TIG welding, sometimes no additional filler wire is needed, and the base material is melted and directly connected. However, filler wire may be used in some cases. Since TIG welding uses pure Ar gas, which is non-oxidizing, the composition of the filler wire remains largely unchanged after melting, making it identical to the weld's composition. In some instances, the base material's composition is used as the filler wire's composition to match the weld with the base material. TIG welding uses lower welding energy, resulting in welds with good strength, plasticity, and toughness that easily meet performance requirements.

2) MIG and MAG Welding Wires:

The MIG method is primarily used for welding stainless steel and other high-alloy steel. To enhance arc characteristics, an appropriate amount of O2 or CO2 gas is added to the Ar gas, transforming it into MAG welding. When welding alloy steel, Ar+5%CO2 gas improves the weld's resistance to porosity. However, when welding ultra-low carbon stainless steel, Ar+5%CO2 gas is unsuitable, and Ar+2%O2 gas is preferred to prevent an increase in carbon content. Currently, low-alloy steel MIG welding is gradually being replaced by MAG welding with Ar+20%CO2. In MAG welding, the protective gas has some oxidizing properties, so the welding wire may need increased Si and Mn deoxidizing elements in its composition. Other components may match the base material or differ slightly. When welding high-strength steel, the weld's C content is typically lower than that of the base material, while the Mn content should be higher, meeting the requirements of the weld metal composition. To improve low-temperature toughness, the Si content in the weld should not be excessively high.

3) CO2 Welding Wire:

CO2 is an active gas with strong oxidizing properties, so welding wires used in CO2 welding must contain higher levels of deoxidizing elements such as Mn and Si. Generally, C-Mn-Si series welding wires, such as H08MnSiA, H08Mn2SiA, and H04Mn2SiA, are used. The welding wire diameter typically ranges from 0.89mm to 2.0mm. Wires with diameters less than or equal to 1.2mm are considered fine-wire CO2 welding, while those with diameters greater than or equal to 1.6mm are considered coarse-wire CO2 welding. H08Mn2SiA welding wire is widely used for CO2 welding and offers good process performance, suitable for welding low-alloy steel with tensile strength below 500MPa. For steel with higher strength requirements, welding wires with Mo elements, such as H10MnSiMo, are preferred.

03丨Welding Wire for Submerged Arc Welding

Submerged arc welding is suitable for welding medium and thick plates, and the welding wire primarily serves as a filler metal and for alloying.

04丨Welding Wire for Non-Ferrous Metals and Cast Iron

Welding wire codes with the first two letters "HS" indicate wires for non-ferrous metals and cast iron. The first digit in the code represents the wire's chemical composition type, while the second and third digits represent different wire grades of the same type.

1) Hardfacing Welding Wire:

Currently, hardfacing with hard alloy welding wires mainly falls into two categories: high chromium alloy cast iron (e.g., Solmaryte) and cobalt-based alloys (e.g., Stellite). High chromium alloy cast iron exhibits excellent oxidation resistance and corrosion resistance, high hardness, and good wear resistance. Cobalt-based alloys maintain high hardness and good corrosion resistance even at high temperatures (650°C). Some have lower carbon and tungsten for improved toughness, while those with high carbon and tungsten have high hardness but reduced impact resistance. The hard alloy hard-facing welding wire can be used for hardfacing using oxy-acetylene or gas welding methods. While oxy-acetylene hard-facing has lower production efficiency, it offers simple equipment, shallow penetration during hard-facing, minimal base material melting, and high hard-facing quality, making it widely used.

2) Copper and Copper Alloy Welding Wire:

Copper and copper alloy welding wires are commonly used for welding copper and copper alloys, with brass welding wire also widely used for brazing carbon steel, cast iron, and hard alloy cutting tools. Welding copper and copper alloys can employ various welding methods, with the correct choice of filler metal being essential to obtain high-quality welds. When using oxy-acetylene gas welding, it is advisable to use it in conjunction with gas welding flux.

3) Aluminum and Aluminum Alloy Welding Wire:

Aluminum and aluminum alloy welding wires are used for aluminum alloy argon arc welding and oxy-acetylene gas welding as filler materials. The choice of welding wire is mainly based on the type of base material, joint cracking resistance, mechanical properties, and corrosion resistance requirements. In most cases, welding aluminum and aluminum alloys should use wires with the same or similar grades as the base material to ensure good corrosion resistance. However, when welding heat-treated aluminum alloys with a high risk of hot cracking, the choice of welding wire primarily focuses on crack resistance, and the composition of the welding wire may differ significantly from the base material.

4) Cast Iron Welding Wire:

Cast iron welding wire is mainly used for gas welding and repair of cast iron. Oxy-acetylene flames have a lower temperature (less than 3400°C) compared to the high-temperature electric arc (6000°C), and they have a wider heat-affected zone. This makes them suitable for repairing gray cast iron and thin-walled cast iron parts. Currently, cast iron welding wires for oxy-acetylene welding mainly include rare earth magnesium alloy and yttrium-based heavy rare earth. Due to yttrium's higher boiling point, it offers better resistance to nodularization degradation, making it more suitable for ensuring welds achieve a nodular cast iron structure, and it has seen increasing use in recent years.

Industry Knowledge