Effect of rolling reduction and annealing process on microstructure and corrosion behavior of LZ91 alloy sheet
(1. International Joint Laboratory for Light Alloys, College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China;
2. State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing 400044, China;
3. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China)
2. State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing 400044, China;
3. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China)
Abstract: The effect of rolling reduction and annealing process on the microstructure and corrosion behavior of Mg-9Li-1Zn (LZ91) alloy was investigated. The test alloy sheets were cold rolled with the reduction of 50% and 75%, respectively, and then were annealed at 200 °C for 1 h. The microstructure of test alloys was observed by OM and SEM while the phase composition was determined by XRD. The corrosion property was evaluated by electrochemical measurements and immersion tests. The results show that LZ91 alloy sheet consists of α-Mg, β-Li and precipitated Mg-Li-Zn compounds (MgLi2Zn and MgLiZn phases). Dynamic recrystallization grains appear in β-Li phase during annealing process, leading to grain refinement. The results indicate that the increasing rolling reduction and performing the annealing process can enhance the corrosion resistance of LZ91 alloy. The 75% cold-rolled and annealed LZ91 alloy shows the best corrosion resistance.
Key words: LZ91 alloy; cold rolling; annealing; microstructure; corrosion resistance