In this work, the corrosion behavior of the ascast and extrusion and aging treatment Mg–2Zn–0.2Mn alloy in simulated body fluid(SBF) were studied. The wear behavior of Mg–2Zn–0.2Mn alloy was investigated using pin...In this work, the corrosion behavior of the ascast and extrusion and aging treatment Mg–2Zn–0.2Mn alloy in simulated body fluid(SBF) were studied. The wear behavior of Mg–2Zn–0.2Mn alloy was investigated using pin-on-disk technique and stainless steel as counterbody under a constant sliding velocity at different loads ranging from 2 to 5 N with deionized water and SBF as lubrication.The results showed that the extrusion and aging treatment Mg–2Zn–0.2Mn alloy exhibited better corrosion resistance compared with the as-cast alloy due to finer average grain size, more homogeneous phase distribution, and decrease in porosity. The friction coefficient of fractional pair under SBF and deionized water lubrication were obviously lower than that of dry sliding condition. However, the wear rate of Mg–2Zn–0.2Mn alloy under SBF lubrication was higher than that of dry sliding and deionized water lubrication due to the corrosiveness of SBF accelerated the wear of the magnesium alloy. The magnesium alloy exhibited different wear mechanisms with the variety of loads and lubrication conditions.展开更多
The main purpose of this paper is to investigate the effect of corrosion on mechanical behaviors of the Mg-Zn-Zr alloy immersed in simulated body fluid （SBF） with different immersion times. The corrosion behavior of...The main purpose of this paper is to investigate the effect of corrosion on mechanical behaviors of the Mg-Zn-Zr alloy immersed in simulated body fluid （SBF） with different immersion times. The corrosion behavior of the materials in SBF was determined by immersion tests. The surfaces of the corroded alloys were examined by SEM. The tensile samples of the extruded Mg-2Zn-0.8Zr magnesium alloy were immersed in the SBF for 0, 4, 7, 10, 14, 21 and 28 d. The tensile mechanical behaviors of test samples were performed on an electronic tensile testing machine. SEM was used to observe the fracture morphology. It was found that with extension of the immersion time, the ultimate tensile strength （UTS）, yield strength （YS） and elongation （EL） of the Mg-2Zn-0.8Zr samples decreased rapidly at first and then decreased slowly. The main fracture mechanism of the alloy transformed from ductile fracture to cleavage fracture with the increasing immersion times, which can be attributed to stress concentration and embrittlement caused by pit corrosion.展开更多
An innovative grade of ferritic stainless steel,ultra-pure 18Cr–2Mo thick plate,was designed and produced for special industrial application.In order to maintain its mechanical properties after joining,three advanced...An innovative grade of ferritic stainless steel,ultra-pure 18Cr–2Mo thick plate,was designed and produced for special industrial application.In order to maintain its mechanical properties after joining,three advanced joining methods,hybrid laser arc welding,activated flux tungsten inert gas welding and friction stir welding,were selected and conducted to connect the thick plates.The feasibility of three joining methods,the microstructure and mechanical properties were compared,and the results have demonstrated that the sound joint was successfully produced using the selected parameters through friction stir welding.The obtained hardness and impact toughness of the weld zone were satisfying.In terms of activated flux tungsten inert gas welding,the crack will be created due to microstructural brittleness.And as for hybrid laser arc welding,the weld zone is narrow,and the addition of wire during welding for the top weld metal area leads to higher formation ratio of low-angle grain boundaries,which is beneficial to performance of the joint.However,there is still a weak area in the fusion line of the welded joint.The result has illustrated that the welding of innovative ultra-pure ferritic stainless steel thick plate by friction stir welding is feasible.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51271131 and 51071108)
文摘In this work, the corrosion behavior of the ascast and extrusion and aging treatment Mg–2Zn–0.2Mn alloy in simulated body fluid(SBF) were studied. The wear behavior of Mg–2Zn–0.2Mn alloy was investigated using pin-on-disk technique and stainless steel as counterbody under a constant sliding velocity at different loads ranging from 2 to 5 N with deionized water and SBF as lubrication.The results showed that the extrusion and aging treatment Mg–2Zn–0.2Mn alloy exhibited better corrosion resistance compared with the as-cast alloy due to finer average grain size, more homogeneous phase distribution, and decrease in porosity. The friction coefficient of fractional pair under SBF and deionized water lubrication were obviously lower than that of dry sliding condition. However, the wear rate of Mg–2Zn–0.2Mn alloy under SBF lubrication was higher than that of dry sliding and deionized water lubrication due to the corrosiveness of SBF accelerated the wear of the magnesium alloy. The magnesium alloy exhibited different wear mechanisms with the variety of loads and lubrication conditions.
基金Acknowledgements Thc authors are grateful for the supports from the National Natural Science Foundation of China （Grant No. 51271131）.
文摘The main purpose of this paper is to investigate the effect of corrosion on mechanical behaviors of the Mg-Zn-Zr alloy immersed in simulated body fluid （SBF） with different immersion times. The corrosion behavior of the materials in SBF was determined by immersion tests. The surfaces of the corroded alloys were examined by SEM. The tensile samples of the extruded Mg-2Zn-0.8Zr magnesium alloy were immersed in the SBF for 0, 4, 7, 10, 14, 21 and 28 d. The tensile mechanical behaviors of test samples were performed on an electronic tensile testing machine. SEM was used to observe the fracture morphology. It was found that with extension of the immersion time, the ultimate tensile strength （UTS）, yield strength （YS） and elongation （EL） of the Mg-2Zn-0.8Zr samples decreased rapidly at first and then decreased slowly. The main fracture mechanism of the alloy transformed from ductile fracture to cleavage fracture with the increasing immersion times, which can be attributed to stress concentration and embrittlement caused by pit corrosion.
文摘An innovative grade of ferritic stainless steel,ultra-pure 18Cr–2Mo thick plate,was designed and produced for special industrial application.In order to maintain its mechanical properties after joining,three advanced joining methods,hybrid laser arc welding,activated flux tungsten inert gas welding and friction stir welding,were selected and conducted to connect the thick plates.The feasibility of three joining methods,the microstructure and mechanical properties were compared,and the results have demonstrated that the sound joint was successfully produced using the selected parameters through friction stir welding.The obtained hardness and impact toughness of the weld zone were satisfying.In terms of activated flux tungsten inert gas welding,the crack will be created due to microstructural brittleness.And as for hybrid laser arc welding,the weld zone is narrow,and the addition of wire during welding for the top weld metal area leads to higher formation ratio of low-angle grain boundaries,which is beneficial to performance of the joint.However,there is still a weak area in the fusion line of the welded joint.The result has illustrated that the welding of innovative ultra-pure ferritic stainless steel thick plate by friction stir welding is feasible.
基金The authors acknowledge the financial support for this work from the National Natural Science Foundation of China （Grant No. 51371126） and the Science and Technology Plan Project of Binhai new area of Tianjin （2012-BK120024）.
