Study On Microstructure And Property Of AZ31B Magnesium Alloy Prepared By Solid State Recycling

Magnesium alloy was widely used in aerospace, transportation, information industry and household. However, the problem of how to deal with the scrap produced by machining process and rejected components is becoming severs. Taking effective measures to recycle magnesium scrap has great significance for resources saving, environmental protection and sustainable development of magnesium industrial.For typical recycle measures of remelting, the recycle rate of magnesium is low, the cost is high, the recycle process is not safe and it is hard to recycle magnesium chips. Plenty of burnout and waste residue are produced using the common remelting method and covering flux and refining flux are added in the remelting process. In this paper, AZ31B magnesium alloy chips and scraps were prepared by solid state recycling. In the solid state recycling process, magnesium alloy chips and scraps were directly extruded into the products by plastic deformation. This measure is safe and easy to carry out. Solid recycling magnesium alloy presents high mechanical property and corrosion resistance.The recycled AZ31B magnesium alloy was prepared by changing chip size, extrusion ratio. The effect of extrusion ratio on the mechanical property and microstructure was studied. The grain size of recycled AZ31B magnesium alloy is decreased with the extrusion ratio increased from 4:1 to 44:1. It is 6.7μm with the extrusion ratio of 40:1. The tensile property and yield stress is increased with the raise extrusion ratio. Tensile property raises form 220MPa to 305MPa. Yield stress increase from 82MPa to 223MPa. The fractographs of recycled AZ31B magnesium was observed. The chips can not be bonding tightly while the extrusion ratio is low. The microstructure of recycled specimens and the specimens extruded form ingot was compared. The gain size of the specimens extruded form ingot is smaller.The different section of recycled specimen was observed. The gain size in the rim of cross section is smaller. The back of extruded specimens has smaller gain size and better mechanical property.Corrosion Behaviors of recycled AZ31B magnesium alloy in 4%NaCl of different PH was discovered. For different extrusion parameters or PH, the process of corrosion is the same.The recycled specimens have better corrosion resistance than that of extrusion form ingot. The corrosion rate and degree is decreased with increased extrusion ratio and decreased chips size. Compared with the side face and cross section the corrosion resistance of the side face is better.