Effect of annealing on microstructure and properties of Cu–30Ni alloy tube

Microstructural evolution and mechanical, and corrosion property evaluation of Cu–30Ni alloy formed by Direct Metal Deposition process

“…Copper based alloys generally have low strength but it has been shown that with different manufacturing techniques and alloying additions superior mechanical and corrosion resistance properties have been realized. Cupro-nickel alloys (primarily Cu-10Ni or Cu-30Ni, with compositions in approximate weight percentages) with some minor alloying additions are widely utilized as engineering materials for making condenser tubes of ships, heat exchangers of coastal power plants, desalination apparatuses and pipelines of desalination plants, boat hulls and several marine engineering applications because of their good corrosion resistance, good ductility, excellent electrical and thermal conductivity and superior anti fouling properties in seawater [12][13][14][15]. Minor iron additions, up to 1.8%, to cupro-nickel alloys have been reported to enhance the corrosion resistance of these alloys.…”

“…Excess alloying additions cause severe segregation and coarsening of the microstructure in alloys produced by conventional casting [15,19]. The microstructure could be homogenized by subsequent annealing and has been shown to improve the mechanical and corrosion properties but are usually time consuming [12,13]. Cupro-nickel alloys produced by rapid solidification techniques such as, planar flow castings and melt spinning have been reported to have better corrosion resistance and mechanical properties compared to those produced by conventional casting.…”

“…Since cupro-nickel alloys are primarily used as marine engineering material, failure of the equipments built with these alloys has been reported to occur primarily due to (i) stress corrosion caused by sulphide or ammonia polluted sea water, (ii) erosion corrosion caused by excessive fluid flow velocities and (iii) crevice or pitting corrosion [1,12,16] in seawater. Corrosion resistances of cupro-nickel alloys are typically compared by (i) weight loss measurements as a function of time and (ii) electrochemical measurements to measure the potentiodynamic polarization of test specimens in artificial or natural seawater solutions [12][13][14]16,20,22].…”

“…Corrosion resistances of cupro-nickel alloys are typically compared by (i) weight loss measurements as a function of time and (ii) electrochemical measurements to measure the potentiodynamic polarization of test specimens in artificial or natural seawater solutions [12][13][14]16,20,22]. During the test, seawater solutions were maintained at a slightly higher temperature and specimens were immersed either in a static bath [1] or in an agitated bath, either by moving the specimen at certain velocity or by aerating the solution to simulate the seawater corrosion [13,14,16,20].…”

Effect of heat treatment on the highly corrosion-resistant Cu70Ni27.7Fe2.3 alloy

“…The Fe-Ni precipitates deteriorate the corrosion performance when the Fe content exceeds 2 at.% in the Cu-Ni alloys containing 10 wt.% Ni [7][8]. It was demonstrated that the mechanical properties of Cu-Ni alloys were influenced by heat treatment [9][10]. Although much research has been devoted to the corrosion behavior of Cu-Ni alloys in seawater, the Fe contents in Cu 70 Ni 30 alloys and the influence of annealing treatment on the microstructure and corrosion behavior of Cu-Ni alloys remain unresolved.…”