Study of Size Effects on Deformation Behavior and Formability in Micro Metal Forming of Ti Foil

2012 ◽  
Author(s):  
Jie Xu ◽  
Bin Guo ◽  
Debin Shan ◽  
Baishun Li
Keyword(s):  
Grain Size ◽  
Flow Stress ◽  
Size Effects ◽  
Deep Drawing ◽  
Metal Forming ◽  
Deformation Behavior ◽  
Foil Thickness ◽  
Micro Scale ◽  
Micro Deep Drawing ◽  
Micro Parts

Micro forming technology becomes a promising approach to fabricate micro-parts due to its advantages of high productivity, low production cost, good product quality and mechanical properties, and near net or net shape characteristics. However, the deformation behaviors of material change and the so-called size effect occurs when the part dimension is decreased to micro-scale. To analyze the quality of micro-parts, the material flow stress, anisotropy, ductility and formability in micro-scale need to be considered. In the paper, micro tensile and micro deep drawing tests of Ti foils were used and the size effects on deformation behavior and formability of micro sheet metal forming were studied. The results show that the flow stress of Ti foils is related with foil thickness and grain size. The fracture behaviors also have been changed from shear dimple to slip separation with the decrease of foil thickness. The formability of micro deep drawing becomes worse with the decrease of micro cup dimension and the increase of grain size.

scholarly journals Study on Micro Hydroforming of Metals

2014 ◽  
Vol 887-888 ◽  
pp. 1133-1138 ◽  
Author(s):  
Liang Luo ◽  
Zheng Yi Jiang ◽  
Dong Bin Wei ◽  
Xiaofeng He
Keyword(s):  
Production Rate ◽  
Size Effects ◽  
Deep Drawing ◽  
Micro Scale ◽  
High Production Rate ◽  
Micro Parts ◽  
High Production ◽  
Similarities And Differences

Micro hydroforming has an ability to manufacture complex 3D micro parts at a high production rate and has drawn increasing attentions. Brief understanding of macro hydroforming, for instance, deep drawing, is necessary to understand the principle of micro hydroforming. Then, special phenomena, such as size effects, occurred at micro scale are discussed and the related theories explaining these phenomena are introduced. Based on the similarities and differences between micro and macro hydroforming, experiments and simulation which consider the size effects are reviewed.

Modeling of Size Effects on the Flow Stress of Type 304 Stainless Steel and Application in Coining Process

2007 ◽  
Author(s):  
Gap-Yong Kim ◽  
Muammer Koc ◽  
Jun Ni
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Flow Stress ◽  
Size Effect ◽  
Size Effects ◽  
Specimen Size ◽  
304 Stainless Steel ◽  
Length Scales ◽  
Type 304 ◽  
Type 304 Stainless Steel

Application of microforming in various research areas has received much attention due to the increased demand for miniature metallic parts that require mass production. For the accurate analysis and design of microforming process, proper modeling of material behavior at the micro/meso-scale is necessary by considering the size effects. Two size effects are known to exist in metallic materials. One is the “grain size” effect, and the other is the “feature/specimen size” effect. This study investigated the “feature/specimen size” effect and introduced a scaling model which combined both feature/specimen and grain size effects. Predicted size effects were compared with experiments obtained from previous research and showed a very good agreement. The model was also applied to forming of micro-features by coining. A flow stress model for Type 304 stainless steel taking into consideration the effect of the grain and feature size was developed and implemented into a finite element simulation tool for an accurate numerical analysis. The scaling model offered a simple way to model the size effect down to length scales of a couple of grains and extended the use of continuum plasticity theories to micro/meso-length scales.

scholarly journals Study on size effects in micro deep drawing of stainless steel foil

2021 ◽  
Vol 2020 (1) ◽  
pp. 012040
Author(s):  
S N Yuan ◽  
H B Xie ◽  
F H Jia ◽  
H Wu ◽  
D Pan ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Size Effects ◽  
Deep Drawing ◽  
Stainless Steel Foil ◽  
Micro Deep Drawing

On the Size Effects in Micro/Meso Upsetting of Brass H62 at Elevated Temperatures

2014 ◽  
Vol 621 ◽  
pp. 158-164
Author(s):  
Hao Yan Wang ◽  
Zhe He Yao ◽  
De Qing Mei
Keyword(s):  
Flow Stress ◽  
Sample Size ◽  
Size Effects ◽  
Metal Forming ◽  
Room Temperature ◽  
Production Efficiency ◽  
Elevated Temperatures ◽  
Processing Temperature ◽  
High Production ◽  
Scaling Down

Micro/meso forming, as an emerging manufacturing process for miniature metallic workpieces, has attracted great attention since the 1990s due to its high production efficiency, low material waste and high precision. Due to the so-called size effects in the scaling down, many traditional theories in metal forming cannot be simply applied to the micro/meso forming. In this study, the micro/meso upsetting experiments of Brass H62 were conducted at various temperatures. The stress−strain curves in the experiments were measured and compared. The effects of the temperature and the sample size on the flow stress were discussed. It is found that the flow stress of the material decreased with the decrease of the sample size at room temperature. However, the flow stress of the material may increase with the decrease of the sample size at elevated temperatures. The results indicate that the size effects in the micro/meso forming are significantly affected by the processing temperature.

Hot Deformation Behavior and Microstructure of U720Li Alloy

2013 ◽  
Vol 709 ◽  
pp. 143-147 ◽  
Author(s):  
Tao Wang ◽  
Zhao Li ◽  
Shu Hong Fu ◽  
Yong Zhang ◽  
Yu Xin Zhao ◽  
...  
Keyword(s):  
Grain Size ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Primary Phase ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
Fine Grain ◽  
Lower Strain

The hot deformation behavior of U720Li was investigated by isothermal compression tests at temperature ranging from 1060-1180°C and strain rate from 0.001s-1 to 20s-1. The flow stress-strain curves and microstructures were investigated and a constitutive equation was established. It is found that flow stress is sensitive to stain rate and deformation temperature greatly. The higher stain rate resultes in a larger fluctuation in flow stress. The hot deformation activation energy is determined to be 552.8kJ/mol. Grain size increases with increasing temperature and decreases firstly and then increases with increasing strain rate. U720Li alloy should be deformed below the solve temperature of γ primary phase with lower strain rate in order to obtain the even and fine grain size.

Mechanical and Laser Micro Deep Drawing

2007 ◽  
Vol 344 ◽  
pp. 799-806 ◽  
Author(s):  
H. Schulze Niehoff ◽  
Zhen Yu Hu ◽  
Frank Vollertsen
Keyword(s):  
Shock Wave ◽  
Size Effects ◽  
Deep Drawing ◽  
Thermal Stresses ◽  
Laser Forming ◽  
Drawing Process ◽  
Deep Drawing Process ◽  
Plasma Generation ◽  
Micro Deep Drawing ◽  
Explosive Forming

Mechanical micro deep drawing becomes a more and more industrial relevant process. But due to size effects new challenges are involved in this process compared to macro deep drawing. The size effects cause an increase of friction and thus hinder the material flow. The change of friction in mechanical micro deep drawing is subject of the presented investigations in this paper. Additionally to this, a new non-mechanical micro deep drawing process is presented, whereby a laser beam acts as a punch. This new laser deep drawing process is based on a totally different mechanism compared to thermal laser forming, e.g. forming by laser induced thermal stresses: The laser produces a pulse with an extremely high power density, which causes plasma generation at the target and thus a shock wave. The shock wave can be used as in explosive forming, but is smaller and easier to generate. Recent investigations showed that using this technology laser deep drawing is possible with a sheet metal out of Al 99.5 and a thickness of 50 'm. The deep drawing process was carried out with a die diameter of 4 mm and shows promising results.

Effects of Specimen Diameter on Microstructure and Microhardness of Hot Extruded AZ31B Magnesium Alloy

2014 ◽  
Vol 1004-1005 ◽  
pp. 158-162 ◽  
Author(s):  
Xiang Ting Hong ◽  
Fu Chen ◽  
Fei Chen ◽  
Wang Yu ◽  
Bo Rong Sang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Size Effects ◽  
Strain Distribution ◽  
Elevated Temperatures ◽  
Az31b Magnesium Alloy ◽  
Specimen Diameter ◽  
Average Grain Size ◽  
Micro Parts

Microstructures of metal micro parts after microforming at elevated temperatures must be evaluated due to mechanical properties depend on average grain size. In this work, the effects of specimen diameter on the microstructure and microhardness of a hot-extruded AZ31B magnesium alloy were studied. Obvious size effect on microstructure and microhardness of the alloy could be observed. The size effects could be explained by strain distribution and dislocation density differences between the two kinds of specimens.

scholarly journals Scaling Anomaly in the Mechanical Response in Microscale Reverse Extrusion of Copper

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Bin Zhang ◽  
W. J. Meng
Keyword(s):  
Grain Size ◽  
Flow Stress ◽  
Metal Forming ◽  
Mechanical Response ◽  
Extrusion Process ◽  
Increasing Demand ◽  
First Time ◽  
Device Miniaturization ◽  
Scaling Anomaly ◽  
Microstructural Examination

Abstract The continuing trend of device miniaturization brings increasing demand for small metal parts and, consequently, significant interest in microscale metal forming technologies. In this work, the influence of grain size on mechanical response in microscale axisymmetric reverse extrusion of Cu 110 alloy was investigated in detail. A characteristic plastic strain associated with material deformation in the extrusion process was, for the first time to the best of our knowledge, defined, measured, and used to evaluate the material's bulk flow stress at this corresponding strain. This flow stress was then used to scale measured mechanical response in reverse extrusion and help identify deviations from scaling behavior expected in continuum plasticity. A scaling anomaly was indeed observed, indicating a dependence of mechanical response on both the initial grain size and the characteristic dimension of microforming operations. Detailed microstructural examination of grains in extruded Cu parts was conducted, and points to directions for future study to better understand mechanisms behind the observed scaling anomaly.

scholarly journals Hot Deformation Behavior and Microstructural Evolution of Twin-Roll-Casting Mg Alloy during High-Temperature Compression

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Qingshan Yang ◽  
Jiahong Dai ◽  
Sensen Chai ◽  
Daliang Yu ◽  
Bin Jiang ◽  
...  
Keyword(s):  
Grain Size ◽  
Flow Stress ◽  
Microstructural Evolution ◽  
Deformation Behavior ◽  
Volume Fraction ◽  
Mg Alloy ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
Average Grain Size ◽  
Twin Roll

The deformation behavior and microstructural evolution of twin-roll-casting AZ31 Mg alloy sheets were investigated via hot compression tests at 0°, 5°, and 10° from the normal direction. Compression strains of 5%, 15%, 25%, and 35% were employed at high temperatures of 450°C and 500°C. The flow stress as well as the difference in the flow stress associated with different sampling directions decreased when the temperature was increased. Furthermore, the volume fraction of dynamically recrystallized grains increased with increasing deformation, whereas the average grain size decreased. The DRX grain size and the volume fraction of dynamically recrystallized grains increased with increasing deformation temperature. During ultrahigh temperature compression, the effect of sampling direction on the compression microstructure is relatively small.

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