What Is The Difference Between Nickel-based Welding Wire And Stainless Steel Welding Wire?

Nickel-based welding wire: The main component is nickel (Ni), and the nickel content is usually above 50%. It also contains various alloy elements such as chromium (Cr), molybdenum (Mo), and niobium (Nb). For example, the chromium content in nickel-based welding wire is generally around 15% - 30%, and the molybdenum content is around 2% - 10%. The addition of these alloy elements can improve the corrosion resistance, high temperature resistance and oxidation resistance of nickel-based welding wire. For example, in some high-temperature corrosion environments, molybdenum can enhance the material's resistance to acidic media.
Stainless steel welding wire: The main component is iron (Fe), the chromium content is generally between 10.5% - 30%, and the nickel content is relatively low, usually around 0 - 22%. In addition to chromium and nickel, it also contains elements such as manganese (Mn) and silicon (Si). For example, the common 304 stainless steel welding wire has a chromium content of about 18% - 20% and a nickel content of about 8% - 10.5%. Stainless steel welding wire mainly relies on the passivation film formed by the chromium element to achieve corrosion resistance.

①Corrosion resistance

Nickel-based welding wire: It has excellent corrosion resistance, especially in harsh environments such as strong acid, alkalinity and high-temperature oxidation. For example, in a medium containing chloride ions, the joints welded by nickel-based welding wire are more resistant to pitting and crevice corrosion than those welded by stainless steel welding wire. This is because nickel-based alloys can form a more stable passivation film, and its alloying elements can play a role in different corrosive environments, such as molybdenum, which can effectively resist the erosion of chloride ions.
Stainless steel welding wire: Corrosion resistance varies depending on the type of stainless steel. It has good corrosion resistance in general atmospheric environments, fresh water and some weak acid and alkali environments, but its corrosion resistance is relatively weak in strong corrosive environments (such as high concentrations of hydrochloric acid, sulfuric acid, etc.). For example, 316L stainless steel welding wire contains more molybdenum than 304 stainless steel welding wire, so in a medium containing a certain amount of salt, such as a marine environment, the structure welded by 316L stainless steel welding wire is more corrosion-resistant.

②High temperature resistance

Nickel-based welding wire: Outstanding high temperature resistance, able to maintain good mechanical properties and oxidation resistance at higher temperatures. For example, some parts welded by nickel-based alloy welding wire can work for a long time in a high temperature environment above 1000℃. This is because nickel-based alloys can form a dense oxide film at high temperatures to prevent oxygen from further corroding the inside of the material, and the alloy elements inside it can strengthen the matrix and prevent the material from deforming and softening at high temperatures.
Stainless steel welding wire: The high temperature resistance is relatively weak, and different types of stainless steel welding wire have different operating temperature ranges. Generally speaking, parts welded by ordinary austenitic stainless steel welding wire may experience problems such as decreased strength and increased oxidation at around 400-600℃. For example, in a high temperature environment, the chromium element at the grain boundary of 304 stainless steel may combine with carbon to form chromium carbide, resulting in a decrease in the chromium content near the grain boundary, thereby reducing the corrosion resistance and high temperature strength of the material.

③Mechanical properties

Nickel-based welding wire: usually has high strength and good toughness, especially at high temperatures. Its tensile strength can reach about 800-1200MPa, and it can also maintain good toughness in a low temperature environment, and is not prone to brittle fracture. This is because the crystal structure of the nickel-based alloy and the strengthening effect of the alloying elements enable the material to withstand large external forces without damage.
Stainless steel welding wire: The mechanical properties vary depending on the type of stainless steel. The parts welded by austenitic stainless steel welding wire have good toughness, but relatively low strength, and the tensile strength is generally around 500-700MPa; the parts welded by martensitic stainless steel welding wire have high strength, but relatively poor toughness. For example, the strength of parts welded by 410 martensitic stainless steel welding wire can be significantly improved after quenching and tempering, but the toughness is not as good as that of parts welded by austenitic stainless steel.

Nickel-based welding wire: widely used in petrochemical, aerospace, marine engineering, nuclear power and other fields. In the petrochemical industry, it is used to manufacture and repair reactors and pipelines resistant to strong corrosion; in the aerospace field, it is used to weld high-temperature alloy parts such as engine blades. For example, in deep-sea oil extraction equipment, the parts welded by nickel-based welding wire can resist the erosion of deep-sea high pressure, high-salinity seawater and corrosive media.
Stainless steel welding wire: mainly used in food processing, architectural decoration, medical equipment, general chemical equipment and other fields. In the food processing industry, it is used to weld stainless steel containers, pipelines, etc. to ensure the safety and hygiene of food; in architectural decoration, it is used to weld stainless steel railings, curtain walls, etc. For example, stainless steel handrails welded by 304 stainless steel welding wire can maintain brightness and corrosion resistance for a long time in indoor environments.

Nickel-based welding wire: welding requires higher heat input because the thermal conductivity of nickel-based alloys is low and the heat dissipation during welding is slow. At the same time, the control requirements for welding parameters (such as welding current, voltage, welding speed, etc.) are more stringent to avoid defects such as thermal cracks. For example, when welding nickel-based alloys using tungsten inert gas welding (TIG welding), the welding current is generally slightly lower than when welding stainless steel, and the welding speed is relatively slow.
Stainless steel welding wire: The welding process is relatively flexible, and the welding speed can be adjusted appropriately according to the actual situation. However, when welding certain special stainless steels (such as martensitic stainless steel), preheating and post-heat treatment are required to prevent cracks. For example, when welding martensitic stainless steel welding wire, it is usually necessary to preheat to 150-300℃, and tempering treatment is performed after welding to improve the toughness and crack resistance of the welded joint.