Improved production procedure for manufacturing chromium bronze bars

Abstract

A thermal deformation treatment (TDT) method is developed and implemented during production of industrial batches of chromium bronze bars, according to which aging is performed after intermediate billetWithin the group of chromium bronzes there are binary copper-chromium or complex chromium-containing lowalloy copper materials [1]. Strengthening is achieved by quenching and subsequent aging, as a result of which chromium or chromium-containing chemical compounds are precipitated [2]. The bulk of chromium-containing alloys in the overall output of low-alloy copper materials is of the order of 60%; copper-chromium and ternary copper-chromium-zirconium systems are used most extensively, whose production reaches 80% of the total volume of chromium bronze output. Alloys based on these two systems, and also other complexly-alloyed chromium-containing alloys, exhibit a unique combination of properties, and this makes it possible to use the alloys in heat exchange units (molds and other installations), electric resistance welding machines (electrodes, armatures), in electrical engineering, electronics, instrument building, and other branches. Chromium bronzes are dispersion-hardened alloys, and therefore the unique properties achieved by optimizing physicochemical properties promoting their productive use are only achieved by heat treatment, which is effectively thermal deformation treatment (TDT). (The terms "thermomechanical treatment" (TMT) and "mechanothermal treatment" (MTT), often used in technical publications, should be considered obsolete. A more functional understanding, combining both versions is considered to be TDT [6], for which the existence and duration of time interval between deformation and heat treatment (or in reverse order) is not an obligatory condition.)Heat treatment (as applied to the group of thermally strengthening alloys is often called "improvement"), as a rule, includes quenching, fixing a supersaturated solution of alloying element in a base, and aging, during which there is decomposition and precipitation of fine particles of the strengthening phase. Only after quenching and subsequent aging is use of chromium bronze more effective, since in other conditions its properties are markedly lower [3,4].However, the level of strength properties obtained for semi-finished products, subjected to aging without prior deformation, under conditions of severe operating regimes, is clearly inadequate [3,4], and in order to satisfy the increasing demands TDT is used, in which between quenching and aging there is cold plastic deformation, having a strong effect on