Method for the production of alloy pipes for heat exchangers using precipitation hardening through underwater extrusion

摘要

Production method for heat exchanger pipes comprising the following stages:
a) production of a billet in an alloy suitable for hardening through precipitation;
b) direct hot extrusion under hydrostatic head in a water bath, of the billet previously heated to a temperature equal to or higher than the solution heat treatment of the alloy, in order to construct an extruded pipe blank of a pre-determined size;
c) cold rolling of the extruded pipe blank to obtain a rolled blank having a reduced transversal measurement and consequently having an increased length;
d) subjecting the rolled blank to a straight drawing process to obtain a semi-finished pipe;
e) subjecting the semi-finished pipe to spinner drawing to reduce the transversal measurement and consequently, to obtain a pipe having its definitive size;
f) subjecting the pipe to annealing in a tunnel furnace in a manner to determine the hardening of the pipe through precipitation.