Metal dusting of pre-carburised 304L stainless steel

The metal dusting behaviour of 304L stainless steel (SS) with or without precarburisation treatment was investigated in a flowing CO/CO₂ atmosphere at the temperature range of 500- 700°C. A thermogravimetric analyser was used to conduct the short term (30 h) exposure tests, while a tube furnace was employed for the prolonged (500 h) tests. The relative resistance to metal dusting and the morphological aspects of the steel with three different surface conditions were compared and examined. The experimental results showed localised attack resulting from metal dusting was found on the surface of the as carburised 304L SS, while it became more uniformly attacked by removing the surface scale formed in pack carburising process before exposure in the CO/CO₂ mixed gas. In a sufficient high carbon activity gas atmosphere, the susceptibility to metal dusting of the as carburised 304L SS increased with increasing temperature.