Abstract Two FeCSi alloys containing 2.20 and 4.16wt.% C are incrementally deposited on a steel substrate by flame spraying. The substrate temperature gradually increases during spraying. The maximum temperature is in the range of about 330 to 670 K depending on the cooling conditions. The cooling rate of the flattened metal droplets during solidification is almost independent of the substrate temperature. As the maximum substrate temperature rises, metastable austenite and a metastable h.c.p. ϵ phase formed on rapid solidification start to decompose during spraying. The cooling rate, the cause of the self-annealing, the decomposition of the metastable phases and the hardness of the deposit layer are examined.