Abstract: A method of sequentially annealing and then hardening long metal components (1,2,3,4) made of fine or special steel with an austenitic structure, said method including at least one annealing operation by supplying heat from the outside in a reducing or neutral atmosphere and one quenching operation by contact with a flow of cooling fluid and an apparatus for putting said method into practice.The flow rate and the temperature of the cooling fluid are adjusted so that the components undergo no transformation of their austenitic structure during hardening.Application to annealing and hardening armoured electric components with conductor cores, inorganic insulant coatings and outer sheaths made of austenitic steel.