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Designed for welding hardenable steels with medium and high carbon content, with or without specific requirements, such as tool steels, shafts, gears, free-cutting steels, dissimilar alloys, bearing layers, overlays, and other similar applications. The combination of high alloy content and ferrite (40-50 FN) ensures exceptional tolerance to dilution across a wide range of hardenable steels and alloys, even with minimal or no preheat. It is particularly effective for welding free-cutting steels or steels with a low Mn:S ratio (especially if <20), where other welding solutions may not prevent hot cracking due to boundary liquation in the fusion zone. The weld deposit is prone to work hardening, providing excellent wear and friction resistance. It is also effective against corrosion and high temperatures up to about 1000 °C. However, it is not recommended for structural applications above 300 °C or for welds requiring post-weld heat treatment due to the risk of embrittlement. Not indicated for heavy joint filling, nor for sub-zero applications where high notch toughness is required.

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 varies based on the base material. Preheat is generally not necessary for small components and bearing layers, but is recommended for thicker high carbon steels to prevent quench cracking in the HAZ and to control maximum hardness, between 100-250 °C. Although 29.9 alloys offer good high-temperature oxidation resistance, the high ferrite content weld metal is susceptible to 475 °C embrittlement at temperatures above 300 °C and sigma phase embrittlement at high temperatures. Therefore, this alloy is not suitable for high-temperature structural applications or where PWHT is expected.