The experimental and numerical simulation methods were employed to study the effect of pressure on the feeding characteristics of ZCuZn16Si4 alloy castings. The results proved that different pressures would lead to di...The experimental and numerical simulation methods were employed to study the effect of pressure on the feeding characteristics of ZCuZn16Si4 alloy castings. The results proved that different pressures would lead to different feeding distance of riser over a suitable pressure range, and the pressure can be used to greatly improve the feeding characteristics compared with gravity casting. It should be pointed out that current porosity criteria in the numerical simulation codes cannot yet be applied well enough to predict the porosity defects of low-pressure copper alloy castings.展开更多
The burst feeding behavior of ZL205 A casting under mechanical vibration and low pressure was investigated by casting experiment and physical model. Experimental results indicated that the burst feeding appeared repea...The burst feeding behavior of ZL205 A casting under mechanical vibration and low pressure was investigated by casting experiment and physical model. Experimental results indicated that the burst feeding appeared repeatedly during solidification and left a shrinkage cavity with layered structure under mechanical vibration. The castings with less shrinkage and higher density could be achieved through the vibration. The calculation results of physical model showed that the burst feeding could perform spontaneously under vibration while difficultly without vibration in low-pressure die casting. The obstruction of a casting could be broken and the grains could be rearranged by the vibration. And the obstruction could be carried away due to the inner and outer pressure difference, causing a burst feeding.展开更多
The burning mechanism during creep feed grinding of titanium alloy with SiC wheel is stud- ied. A CBN intermittent creep feed grinding technology combining the advantages of CBN, intermittent grinding and creep feed ...The burning mechanism during creep feed grinding of titanium alloy with SiC wheel is stud- ied. A CBN intermittent creep feed grinding technology combining the advantages of CBN, intermittent grinding and creep feed grinding is recommended. The results show that the intermittent CBN wheel has a bright future in resolving the problem of workpiece burning during creep feed grinding of titanium al- loys展开更多
Turning clearance angle is changed machining characteristics. In this study, the experiments start from choosing two workpiece materials that are machine structural carbon steel, chrome-molyb- denum steel. Then, the e...Turning clearance angle is changed machining characteristics. In this study, the experiments start from choosing two workpiece materials that are machine structural carbon steel, chrome-molyb- denum steel. Then, the experiments show specifically how features of selected materials changed when they were processed with machining operation. In order to find the surface roughness of workpiece materials, the workpiece materials which have higher tensile strength showed much better value of surface roughness in a surface roughness tester. Moreover, process feed rate was compared between 0.05 mm/rev and 0.10 mm/rev. When process feed rate was 0.05 mm/rev, surface roughness has superior results without reference to the quality of the materials.展开更多
The application of ultrasonic vibration during the casting process has been proven to refine the microstructure and enhance the properties of the casting.By using the direct inserting method,wherein the ultrasonic hor...The application of ultrasonic vibration during the casting process has been proven to refine the microstructure and enhance the properties of the casting.By using the direct inserting method,wherein the ultrasonic horn is inserted directly into the melt,ultrasonic treatment can be utilized in the semi-continuous casting process to produce aluminum ingots with simple shapes.However,due to the attenuation of ultrasound,it is challenging to apply the direct inserting method in the die casting process to produce complex castings.Thus,in this study,the impact of ultrasonic vibration on the microstructure of a gravity die-cast AlSi9Cu3end cap was investigated by applying ultrasonic vibration on the core(indirect method).It is found that the effect of ultrasonic vibration relies greatly on the resonance mode of the core.Selection of ultrasonic vibration schemes mainly depends on the core structure,and only a strong vibration can significantly refine the microstructure of the casting.For castings with complex structures,an elaborated ultrasonic vibration design is necessary to refine the microstructure of the specified casting.In addition,strong vibration applied on the feeding channel can promote the feeding ability of casting by breaking the dendrites during solidification,and consequently reduce the shrinkage porosity.展开更多
Coarse columnar β grains result in anisotropic mechanical properties in Ti alloys deposited by additive manufacturing. This study reports that Ti-6Al-4V alloy fabricated by coaxial electron beam wire feeding additive...Coarse columnar β grains result in anisotropic mechanical properties in Ti alloys deposited by additive manufacturing. This study reports that Ti-6Al-4V alloy fabricated by coaxial electron beam wire feeding additive manufacturing presents a weak anisotropy, high strength and ductility. The superior tensile property arises from a microstructure with fine equiaxed β grains(EGβ), discontinuous grain boundary α phase and short intragranular α lamellae. A large region of fine EGβ arises from a special combination of the temperature gradient and solidification rate, and attractive α morphology is caused by solid phase transformations during interpass thermal cycling and post heat treatments.展开更多
文摘The experimental and numerical simulation methods were employed to study the effect of pressure on the feeding characteristics of ZCuZn16Si4 alloy castings. The results proved that different pressures would lead to different feeding distance of riser over a suitable pressure range, and the pressure can be used to greatly improve the feeding characteristics compared with gravity casting. It should be pointed out that current porosity criteria in the numerical simulation codes cannot yet be applied well enough to predict the porosity defects of low-pressure copper alloy castings.
基金Projects(51475120,U1537201) supported by the National Natural Science Foundation of China
文摘The burst feeding behavior of ZL205 A casting under mechanical vibration and low pressure was investigated by casting experiment and physical model. Experimental results indicated that the burst feeding appeared repeatedly during solidification and left a shrinkage cavity with layered structure under mechanical vibration. The castings with less shrinkage and higher density could be achieved through the vibration. The calculation results of physical model showed that the burst feeding could perform spontaneously under vibration while difficultly without vibration in low-pressure die casting. The obstruction of a casting could be broken and the grains could be rearranged by the vibration. And the obstruction could be carried away due to the inner and outer pressure difference, causing a burst feeding.
文摘The burning mechanism during creep feed grinding of titanium alloy with SiC wheel is stud- ied. A CBN intermittent creep feed grinding technology combining the advantages of CBN, intermittent grinding and creep feed grinding is recommended. The results show that the intermittent CBN wheel has a bright future in resolving the problem of workpiece burning during creep feed grinding of titanium al- loys
文摘Turning clearance angle is changed machining characteristics. In this study, the experiments start from choosing two workpiece materials that are machine structural carbon steel, chrome-molyb- denum steel. Then, the experiments show specifically how features of selected materials changed when they were processed with machining operation. In order to find the surface roughness of workpiece materials, the workpiece materials which have higher tensile strength showed much better value of surface roughness in a surface roughness tester. Moreover, process feed rate was compared between 0.05 mm/rev and 0.10 mm/rev. When process feed rate was 0.05 mm/rev, surface roughness has superior results without reference to the quality of the materials.
基金supported by the Natural Science Foundation of Shandong province(Grant No.ZR2021ME023)the Innovation Team Project of Jinan,China(Grant No.2019GXRC035)SQ project[2021370113124591]。
文摘The application of ultrasonic vibration during the casting process has been proven to refine the microstructure and enhance the properties of the casting.By using the direct inserting method,wherein the ultrasonic horn is inserted directly into the melt,ultrasonic treatment can be utilized in the semi-continuous casting process to produce aluminum ingots with simple shapes.However,due to the attenuation of ultrasound,it is challenging to apply the direct inserting method in the die casting process to produce complex castings.Thus,in this study,the impact of ultrasonic vibration on the microstructure of a gravity die-cast AlSi9Cu3end cap was investigated by applying ultrasonic vibration on the core(indirect method).It is found that the effect of ultrasonic vibration relies greatly on the resonance mode of the core.Selection of ultrasonic vibration schemes mainly depends on the core structure,and only a strong vibration can significantly refine the microstructure of the casting.For castings with complex structures,an elaborated ultrasonic vibration design is necessary to refine the microstructure of the specified casting.In addition,strong vibration applied on the feeding channel can promote the feeding ability of casting by breaking the dendrites during solidification,and consequently reduce the shrinkage porosity.
基金supported by the internal funding source from University of Shanghai for Science and Technology.
文摘Coarse columnar β grains result in anisotropic mechanical properties in Ti alloys deposited by additive manufacturing. This study reports that Ti-6Al-4V alloy fabricated by coaxial electron beam wire feeding additive manufacturing presents a weak anisotropy, high strength and ductility. The superior tensile property arises from a microstructure with fine equiaxed β grains(EGβ), discontinuous grain boundary α phase and short intragranular α lamellae. A large region of fine EGβ arises from a special combination of the temperature gradient and solidification rate, and attractive α morphology is caused by solid phase transformations during interpass thermal cycling and post heat treatments.
