312

Suitable for welding medium and high carbon hardenable steels, including those with known or unknown specifications like tool steels, shafts, gear teeth, free-cutting steels, dissimilar alloy combinations, buffer layers, overlays, etc. The welding material, featuring a high alloy and high ferrite content (40-50FN), exhibits exceptional tolerance to dilution on a wide range of hardenable and alloy steels, often requiring minimal or no preheat. It is effective for welding free-cutting steels or those with a low Mn:S ratio, especially below 20, preventing hot cracking due to liquation at the fusion boundary. The resulting weld deposit work-hardens, offering excellent wear and friction resistance. It is useful for corrosion resistance and high-temperature scaling up to about 1000°C. However, it's not recommended for structural applications above 300°C or for welds that undergo post-weld heat treatment due to potential embrittlement. Additionally, it is not suitable for filling up heavy joints, sub-zero applications, or situations requiring high notch toughness.

Austenite-ferrite weld metal composition of nominally 29%Cr-9%Ni for dissimilar joints and difficult to weld steels.

Duplex austenite-ferrite microstructure with about 40% ferrite.

Medium and high carbon hardenable steels, tool steels and free-cutting steels.

The procedure is contingent upon the base material. Preheating is generally unnecessary for small components and buffer layers; however, it is advisable for thicker high-carbon steels to prevent potential Heat-Affected Zone (HAZ) quench cracking and regulate peak hardness, typically in the range of 100-250°C. Despite the excellent high-temperature oxidation resistance of 29%Cr-9%Ni alloys, it's crucial to note that duplex high ferrite weld metal may experience 475°C embrittlement above approximately 300°C and sigma embrittlement at elevated temperatures. Consequently, this alloy is not employed in applications involving high-temperature structural service or Post Weld Heat Treatment (PWHT).