The objective of this work is to study the cryogenic sheet metal forming behaviour of precipitation hardening AW-6016-T4.In this regard,the flow curves and forming limit curves were obtained by tension and Nakazima ex...The objective of this work is to study the cryogenic sheet metal forming behaviour of precipitation hardening AW-6016-T4.In this regard,the flow curves and forming limit curves were obtained by tension and Nakazima experimental testing methods in thetemperature ranges from-196to25°C.It was found that strength and elongation increase with decreasing temperature.Small butperceived differences between microstructure of the material deformed at the room and cryogenic temperatures respectively wereidentified by electron backscatter diffraction(EBSD)analysis.However,no significant difference in the precipitation kinetics duringcontinuous heating in the DSC has been observed.This study has demonstrated the potential of cryogenic forming by manufacturinga B-pillar part with8mm depth of side design element as compared to6mm at room temperature.展开更多
Materials with the same elastic modulus E and representative stress and strain （σr,εr） present similar indentation-loading curves, whatever the value of strain hardening exponent n. Based on this definition, a goo...Materials with the same elastic modulus E and representative stress and strain （σr,εr） present similar indentation-loading curves, whatever the value of strain hardening exponent n. Based on this definition, a good approach was proposed to extract the plastic properties or constitutive equations of metals from nanoindentation test combining finite element simulation. Firstly, without consideration of strain hardening, the representative stress was determined by varying assumed representative stress over a wide range until a good agreement was reached between the computed and experimental loading curves. Similarly, the corresponding representative strain was determined with different hypothetical values of strain hardening exponent in the range of 0-0.6. Through modulating assumed strain hardening exponent values to make the computed unloading curve coincide with that of the experiment, the real strain hardening exponent was acquired. Once the strain hardening exponent was determined, the initial yield stress ay of metals could be obtained by the power law constitution. The validity of the proposed methodology was verified by three real metals： AISI 304 steel, Fe andA1 alloy.展开更多
基金the Austrian Research Promotion Agency (FFG)the Federal Ministry for Transport, Innovation and Technology (bmvit) for sponsoring the project Kryo Alu in the framework of Kooperative F&E-Projekte-Industrielle Forschung, Experimentelle Entwicklung
文摘The objective of this work is to study the cryogenic sheet metal forming behaviour of precipitation hardening AW-6016-T4.In this regard,the flow curves and forming limit curves were obtained by tension and Nakazima experimental testing methods in thetemperature ranges from-196to25°C.It was found that strength and elongation increase with decreasing temperature.Small butperceived differences between microstructure of the material deformed at the room and cryogenic temperatures respectively wereidentified by electron backscatter diffraction(EBSD)analysis.However,no significant difference in the precipitation kinetics duringcontinuous heating in the DSC has been observed.This study has demonstrated the potential of cryogenic forming by manufacturinga B-pillar part with8mm depth of side design element as compared to6mm at room temperature.
基金Project （51171125） supported by the National Natural Science Foundation of China Project （20110321051 ） supported by the Science and Technology Key Project of Shanxi Province, China
文摘Materials with the same elastic modulus E and representative stress and strain （σr,εr） present similar indentation-loading curves, whatever the value of strain hardening exponent n. Based on this definition, a good approach was proposed to extract the plastic properties or constitutive equations of metals from nanoindentation test combining finite element simulation. Firstly, without consideration of strain hardening, the representative stress was determined by varying assumed representative stress over a wide range until a good agreement was reached between the computed and experimental loading curves. Similarly, the corresponding representative strain was determined with different hypothetical values of strain hardening exponent in the range of 0-0.6. Through modulating assumed strain hardening exponent values to make the computed unloading curve coincide with that of the experiment, the real strain hardening exponent was acquired. Once the strain hardening exponent was determined, the initial yield stress ay of metals could be obtained by the power law constitution. The validity of the proposed methodology was verified by three real metals： AISI 304 steel, Fe andA1 alloy.
