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Copper and brass radiators have served the automobile industry for many years using traditional fabrication processes. Demand for newer and stronger radiators with lighter weight for the modern vehicles prompted investigation of alternate materials. Properties of zinc alloys and their compatibility with brass suggested these could be used for radiator manufacture. Many zinc alloy compositions were investigated in the initial studies, because a solder alloy has to have many positive attributes. The first screening studies evaluated the ability of the solder to spread over copper and brass surfaces, representing tube, fin, and header materials. The second most important feature was the melting range of the developed alloy. In order to retain the anneal resistance of the fin and temper in the tube it was desirable to have a zinc solder with a melting temperature at 800°F or less.

The demands for longer lifetimes of cars have meant that the durability of radiators has also become more important, particularly with regard to the resistance to external corrosion due to environmental pollution. In this paper corrosion mechanisms, as well as some preventive measures for copper/brass radiators, are discussed. The radiator is constructed basically of solder–coated flat brass tubes and copper fins. The tubes and fins are joined together with tinllead solder. Bimetallic contact points in joints and also pores and scratches are exposed to corrosive chloride and sulfur compounds. This can initiatiate corrosion damage, if corrosion prevention measures have not been taken into consideration. Experiments have been made to evaluate the risks of bimetallic corrosion between copper, some brass alloys and soldering alloys on radiators. Experiments are based on electrochemical methods.

Automotive radiator designers require practical design load limits to avoid stress-and stress-corrosion failures under current and anticipated operating conditions. Today, brass radiator materials are evaluated on the basis of coupon corrosion specimens and full-scale engine tests. Coupons provide only limited information while engine tests are time-consuming and costly. An alternative method known as slow strain rate tensile testing provides valid, quantitative information on the performance of radiator materials under controlled conditions that closely simulate radiator service conditions. The test, developed 20 years ago and widely used in several technologies, enables rapid evaluation of radiator materials, coolants and to some extent, radiator fabrication methods.