Welding rods are essential tools for maintaining the integrity of metal structures, including heat resistant steels such as those used for boilers, kilns and industrial furnaces. Heat-resistant steels, along with nickel alloys, are widely used for the fabrication and repair of high-temperature components and vessels. These materials are ideal for generating process heat and resisting hot corrosion, making them the perfect choice for welders in the many manufacturing processes which require working with high temperatures.
Since heat resistant steels are typically used at high temperature levels and are subject to thermal, structural and mechanical fatigue, and have limited creep resistance, they require special attention when welding. Selection of the right welding rod is imperative to ensure safe, durable and sound welds.
Selection of the correct welding rod for heat resistant steels depends on the type of steel, the thickness of the material, the welding process and the ambient conditions. Furthermore, the weld joint design, the welding environment and the welding position can also play an important role in making the right choice.
Heat resistant steels feature an austenitic structure, a high temperature strength and a resistance to both oxidation and scaling at elevated temperatures. Generally speaking, the two main types of heat resistant steels used for welding are the relatively low-alloyed carbon steel (Type 300 series) and the higher-alloyed austenitic steel (Type 400 series).
When selecting a welding rod for heat resistant steels, it’s important to consider the base metal and its temperature requirements as well as the type of weld joint. Some grades of heat resistant steels are best welded using certain types of rods while other grades are better suited to others. For example, when welding austenitic grades of type 400 series steels, a stainless steel rod is generally the best choice to ensure the weld will hold up against the higher temperature. On the other hand, when welding carbon steels of type 300 series, a nickel based filler metal is usually the most effective.
Welding rod selection also depends on the welding process. Heat resistant steels can be successfully welded using shielded metal arc welding (SMAW or stick welding) as well as gas tungsten arc welding (GTAW or TIG welding). Some manufacturers of GTAW rods specifically recommend types of electrodes for welding various grades of heat resistant steels. Generally speaking, metal cored electrodes are ideal for thicker sections of type 400 series steels while bare electrodes are better for thin sections.
The appropriate welding rod for heat resistant steels must be corrosion and heat resistant, as well as have good ductility and low thermal diffusivity. It’s important to research each type of welding rod thoroughly to determine which are most suited to the grades of heat resistant steels in the specific welding application.
Heat resistant steels can present a unique set of challenges for welders so making the right welding rod selection is like investing in assurance for a quality job. With the right welding rod, welders can create sound, durable and safe joints - even in high-temperature applications.
