Abstract: The invention relates to a carbonitriding facility (IC) which includes: a heating chamber (CC), for heating at least one steel part (PA) to a first temperature, in the presence of a neutral gas and under a selected pressure; a first enriching chamber (CE1) for enriching the heated part with nitrogen, by nitriding same in ?-phase at a second temperature no higher than the first temperature; a second enriching chamber (CE2) for enriching the nitrogen-enriched part with carbon, by carburising same at a third temperature higher than the second temperature; a quench chamber (CT) for quenching the nitrogen- and carbon-enriched part under pressure; a transfer airlock (ST) communicating with the chambers and suitable for temporarily receiving the part in a controlled atmosphere; and transfer means (MT) for transfer-ring the part from one chamber to another chamber via the transfer airlock (ST).