| 摘要 |
Process for producing an atmosphere for the heat treatment of metals, formed by introducing a gaseous stream of nitrogen, according to which there is first of all formed, by separating air using selective permeation, a crude gaseous stream of nitrogen with a residual oxygen content, to which a flow of hydrogen is added which is at least sufficient to remove most of the residual oxygen by catalytic reaction forming water vapour, and the water vapour is extracted, characterised by the combined use of the following measures: a) the gaseous stream of nitrogen has a residual oxygen content of between 0.5 % and 1 %; b) the catalytic reaction forming water vapour is free from any external heat input; c) the residual oxygen content is lower than 30 vpm, with establishment of a water vapour content between 0.5 % and 2 % relative to the nitrogen flow rate; d) the substantial extraction of the water vapour is performed exclusively by exchange with a cold fluid with a final stage of exchange with a refrigerant unit; e) the substantial extraction of the water vapour according to d is conducted so that the residual water vapour content is between 2000 vpm and 350 vpm relative to the total flow rate. Exclusive application to the annealing, or welding, or heating before quenching of carbon steels or of low-alloy steel, to the sintering of ferrous metals and to the welding of aluminium.
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