| Aluminum brass tubes are often used in the condensers as heat exchange materials for their good processing performance,excellent corrosion resistance and good heat transfer performance.But low-cost aluminum brass tubes exist obvious tendency of dezincification corrosion.So it is meaningfull to improve the corrosion resistance of aluminum brass alloy,prolong the service life of alloy steel tubes.this experiment,using the orthogonal experiment design method,study the corrosion resistance and mechanical properties of different content of B ? Sn ? Ce elements in HAl77-2 aluminium brass by the static corrosion test,electrochemical test,metallographic(OM),scanning electron microscope(SEM),room temperature tensile and phase analysis(XRD).The results show that:(1)HAl77-2 aluminium brass is single-phase ? group with Cu0.64Zn0.36 for substrate,the alloy phase does not changes after adding the different content of B,Sn,Ce element.The three elements are solution in alloy substrate and aging strengthened,which increasing the hardness values.(2)These three elements of B?Sn?Ce are effective to improve the corrosion resistance of brass.in the aspect of dezincification corrosion resistance,the influence degree of each element in order: B > Sn > Ce,Each element in the seawater corrosion performance,influence degree sequence is: Sn > B > Ce.tested on the orthogonal test of each sample Through static corrosion test,electrochemical properties and corrosion morphology analysis.The results show that alloy specimens' corrosion rate is the smallest in both different solution,Corrosion on the surface of the smoothest,electrochemical corrosion properties of the weakest,the corrosion resistance of the strongest,which is added 0.05% B?0.5% Sn?0.15% Ce.Finally compare the theoretically best sample and the experiment best sample,and Found that the experiment best sample's corrosion resistance is superior to the theoretically best sample's,which is added 0.03% B?1.5% Sn?0.15% Ce.The Results show that the best to improve the corrosion resistance of the alloy composition is alloy added 0.05% B?0.5% Sn?0.15% Ce.(3)the optimal alloy added 0.05% B?0.5% Sn?0.15% Ce is obvious different under different state.The Corrosion resistance order from strong to weak is: annealed state> recrystallize state> as-cast> cold rolling state.The corrosion rate of diffusion annealing sample by 800 ? ×4h is minimum and its average dezincification layer is only 332.2?m.recrystallized samples has better mechanical property than other alloy specimens of different states for its small crystal structure.(4)Recrystallization annealing process had significant effect on the performance of alloy.Under different annealing temperature,the influence degree of annealing time on the electrochemical properties of alloy is different.the difference is the largest under 400?,and is minimal under 600?.Under the condition of the same annealing time,with the increase of annealing temperature,the corrosion rate of alloy decrease first,then increase and tensile strength and elongation increase first,then decrease.(5)the corrosion rate of the optimal alloy by 800?×4h diffusion annealing,75% cold rolling process,and then 500?×3h recrystallization annealing decline first,after rising,and then tend to be stable with the increase of Cl-concentration;first fall sharply,leveling off,and then slightly decreased,at last increased dramatically with the increase of p H.the corrosion rate is the minimize in the environment of weak alkali,the biggest in the environment of strong acid.the corrosion rate and Cl-concentration meet 4 power function relationship,the function equation is :y = 8.3728-86.873 * + 402.2092 * 2-544.4629 * 3+ 232.9160 * 4Among them:y—corrosion rate;x—Cl-concentration When the concentration of Cl-is 0.18mol/L,the corrosion rate of alloy is minimal. |
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