In this paper, repeated unidirectional bending （RUB）, was applied to improve the texture of AZ31B magnesium alloy sheets so as to enhance their stamping properties. The samples undergoing RUB were annealed at differ...In this paper, repeated unidirectional bending （RUB）, was applied to improve the texture of AZ31B magnesium alloy sheets so as to enhance their stamping properties. The samples undergoing RUB were annealed at different temperatures. The mechanical properties, formability, textural components and microstructure of the samples before and after RUB were characterized and compared. It was found that the basal textural component was reduced dramatically by RUB, and that （1212） and （1211） textural components appeared. Annealing has a great effect on the mechanical properties of samples undergoing RUB. The plasticity and stamping formability of samples were greatly improved by RUB and annealing at 260℃ for 1 h, and elongation to fracture and Erichsen value were increased to 38% and 67%, respectively.展开更多
The morphology change of the magnesium matrix after pre-treatment and the morphology as well as the phase composition of chemical conversion coating formed by phosphate were studied using scanning electron microscope ...The morphology change of the magnesium matrix after pre-treatment and the morphology as well as the phase composition of chemical conversion coating formed by phosphate were studied using scanning electron microscope and X-ray diffraction. The corrosion resistance of the coating was studied by salt spray and damp test, and the corrosion tendency during salt immersion test was analyzed. The results show that the phase composition before and after pre-treatment is almost changeless, and the deep microflaw appears between a andβ phases during acidic pickling. The phosphate conversion coating is mainly composed of Mg, MgO, and some amorphous phase, and it can provide a good protection for the AZ31B alloy. Results from corrosive morphology indicate that the growth and the corrosion resistance of the phosphate conversion coating are related to the forming process of the AZ31B matrix.展开更多
Biodegradable magnesium-based alloys are very promising materials for temporary implants. Laser welding is an important joining method in such application. In this study, the as-rolled AZ31B magnesium alloy sheets of ...Biodegradable magnesium-based alloys are very promising materials for temporary implants. Laser welding is an important joining method in such application. In this study, the as-rolled AZ31B magnesium alloy sheets of 1 mm in thickness were successfully joined by Nd ： YAG laser welding. The microstructure and properties of the welded joint were investigated. The result shows that the welded joint is characterized by a narrow heat-affected zone, finer grains and a large number of precipitates distribute in the matrix in the weld. Microhardness of the weld is significantly improved to 72 HV 0. 05 as compared to 55 HV 0. 05 of the base metal. Tensile strength of butt-welded joint is 180. 24 MPa, which is 76. 8% that of the base metal. The electrochemical corrosion experiment shows that the corrosion resistance of laser welded joint is significantly improved in a 3.5 wt. % NaCl solution.展开更多
An attempt has been made to improve the surface properties of AZ31B magnesium alloy through solid solution hardening and refinement of microstructures using a CO2 laser as a heat generating source. X-ray diffraction ...An attempt has been made to improve the surface properties of AZ31B magnesium alloy through solid solution hardening and refinement of microstructures using a CO2 laser as a heat generating source. X-ray diffraction （XRD） was used to identify the phases. Microstructure and properties of laser melted layer of AZ31B magnesium alloy were observed or tested by means of optical microscope （OM）, scanning electron microscope （SEM）, micro-hardness equipment and electrochemical corrosion equipment etc. The results show that the microstructure of laser melted layer becomes finer significantly and uniform. Compared with the substrate, the content of β-Mg17 Al12 phase of melted layer decreases comparatively. Microhardness of the laser melted layer is improved to 50 -95 HV0. 05 as compared to 40 -45 HV0.05 of the AZ31B Mg alloy substrate. The results of electrochemical corrosion show that the corrosion resistance of laser surface melted layer has been improved.展开更多
基金supported by the National Natural Science Foundation of China under Grant No. 50504019Natural Science Foundation Project of CQ CSTC under Grant No. 2008BB4040
文摘In this paper, repeated unidirectional bending （RUB）, was applied to improve the texture of AZ31B magnesium alloy sheets so as to enhance their stamping properties. The samples undergoing RUB were annealed at different temperatures. The mechanical properties, formability, textural components and microstructure of the samples before and after RUB were characterized and compared. It was found that the basal textural component was reduced dramatically by RUB, and that （1212） and （1211） textural components appeared. Annealing has a great effect on the mechanical properties of samples undergoing RUB. The plasticity and stamping formability of samples were greatly improved by RUB and annealing at 260℃ for 1 h, and elongation to fracture and Erichsen value were increased to 38% and 67%, respectively.
基金supported by the National Natural Science Foundation of China(No.50474007)Science and Technology Project of Jiangxi Provincial Departmentof Education (No.[2006]1)
文摘The morphology change of the magnesium matrix after pre-treatment and the morphology as well as the phase composition of chemical conversion coating formed by phosphate were studied using scanning electron microscope and X-ray diffraction. The corrosion resistance of the coating was studied by salt spray and damp test, and the corrosion tendency during salt immersion test was analyzed. The results show that the phase composition before and after pre-treatment is almost changeless, and the deep microflaw appears between a andβ phases during acidic pickling. The phosphate conversion coating is mainly composed of Mg, MgO, and some amorphous phase, and it can provide a good protection for the AZ31B alloy. Results from corrosive morphology indicate that the growth and the corrosion resistance of the phosphate conversion coating are related to the forming process of the AZ31B matrix.
基金The work was supported by the National Natural Science Foundation of China （ Grant No. 51305292 ） and the Aviation Science Foundation （ Grant No. 20105429001 ）.
文摘Biodegradable magnesium-based alloys are very promising materials for temporary implants. Laser welding is an important joining method in such application. In this study, the as-rolled AZ31B magnesium alloy sheets of 1 mm in thickness were successfully joined by Nd ： YAG laser welding. The microstructure and properties of the welded joint were investigated. The result shows that the welded joint is characterized by a narrow heat-affected zone, finer grains and a large number of precipitates distribute in the matrix in the weld. Microhardness of the weld is significantly improved to 72 HV 0. 05 as compared to 55 HV 0. 05 of the base metal. Tensile strength of butt-welded joint is 180. 24 MPa, which is 76. 8% that of the base metal. The electrochemical corrosion experiment shows that the corrosion resistance of laser welded joint is significantly improved in a 3.5 wt. % NaCl solution.
基金The research is supported by the Shanxi Natural Science Foundation （No. 2008011044）.
文摘An attempt has been made to improve the surface properties of AZ31B magnesium alloy through solid solution hardening and refinement of microstructures using a CO2 laser as a heat generating source. X-ray diffraction （XRD） was used to identify the phases. Microstructure and properties of laser melted layer of AZ31B magnesium alloy were observed or tested by means of optical microscope （OM）, scanning electron microscope （SEM）, micro-hardness equipment and electrochemical corrosion equipment etc. The results show that the microstructure of laser melted layer becomes finer significantly and uniform. Compared with the substrate, the content of β-Mg17 Al12 phase of melted layer decreases comparatively. Microhardness of the laser melted layer is improved to 50 -95 HV0. 05 as compared to 40 -45 HV0.05 of the AZ31B Mg alloy substrate. The results of electrochemical corrosion show that the corrosion resistance of laser surface melted layer has been improved.
