Microstructure Evolution And Condensation Brass Casting Process Of Copper Condenser Corrosion Resistance Study

This paper studied microstructure and properties of the pure coppercondenser tubes with the cast state and the rolling state of a three-rollplanetary; we simulated the rolling process through the hot compress test,analyzed the deformation mechanism during the rolling process of thethree-roll planetary according the varied tendency of the microstructureand properties; we analyzed corrosion mechanism of copper condensertubes using for heat exchanging in different corrosion system, through theexperiments in the conditions of 3.5%NaCl, 0.5%Na₂S, 900mg/L aquaammonia. The conclusions are drawn as follows:1. The radial macrostructure of the horizon continual casting theouter was the columnar crystal, the inner was the equaxed crystal. Thegrain size of the rolling state was homogenous, and we could find thedynamic recrystallization and the annealing twin. The copper tubessuffered two contrary processes both work-hardening and dynamicrecrystallization softening during the roll process of the three-rollplanetary, and obtained the dynamic recrystallization after the roll.2. In the thermal simulation test, the gain size was becoming smallcorresponding with the increasing of the anamorphic degree, and thedegree of the recrystallization was becoming homogenous. The holdingtime was only affected the size of the grain. It was easier that therecrystallization occurred, with the greater rate of the deformation. Thechange of deformation temperature obviously affected the structure of thedeformation; we also could judge the transformation trend of the innergrain during the process of dynamic recrystallization according it.3. The similar structure of the crystal with the practical in the state ofthe rolling process of the three-planetary could be simulated, in the testcondition of the deformation temperature 700℃, deformation degree 75%,deformation rate 1 s^-1, holding time 3min.4. Compared with red copper, brass HSn70-1, the ambrose alloyBFe30-1-1 and the ambrose alloy BFe30-1-1, all of the four copper tubeshad better corrosion resistance in the aqua ammonia system. Comparedthe properties of corrosion resistance in the three corrosion systems, the HSn70-1 was the best of the copper alloys. The brass occurreddezincification in the chloride system, the ambrose alloy BFe30-1-1occurred denickel corrosion in the sulfide system.