Evaluation of Friction Properties of Magnesium Alloy during Hot Forging by Ring Compression Test

2017 ◽  
Vol 889 ◽  
pp. 119-126
Author(s):  
Sueji Hirawatari ◽  
Hisaki Watari ◽  
Shinichi Nishida ◽  
Yuki Sato ◽  
Mayumi Suzuki
Keyword(s):  
Magnesium Alloys ◽  
Compression Test ◽  
Hot Forging ◽  
Hot Forming ◽  
Compression Tests ◽  
Ring Compression Test ◽  
Stress Strain ◽  
Friction Coefficients ◽  
Ring Compression ◽  
Velocity Motion

This paper deals with friction properties and deformation resistance during hot forming of Mg-Al-Ca-Mn series magnesium alloys. Friction coefficients between dies and magnesium alloys were obtained by ring compression tests that used graphite, PTFE, and an oil lubricant in a hot-forging process. Hot forging was performed under various conditions to clarify the effects of types of lubricants and slide motion of the press machines on friction properties. Two types of slide motion, a constant velocity motion and a pulse motion were selected in the ring-compression test. It was found that graphite with an oil lubricant effectively eliminated die sticking in hot forming of magnesium alloys. The isothermal deformation resistances were derived using friction coefficients obtained by ring-compression tests as well as finite-element simulations. The predicted stress strain curves with temperature were examined with the stress-strain relationship obtained in experiments using a servo press and demonstrated the effectiveness of the proposed method.

Development of a Testing Method for the Identification of Friction Coefficients for Numerical Modeling of the Shear-Clinching Process

2015 ◽  
Vol 639 ◽  
pp. 469-476 ◽  
Author(s):  
Martin Müller ◽  
Ulrich Vierzigmann ◽  
Réjane Hörhold ◽  
Gerson Meschut ◽  
Marion Merklein
Keyword(s):  
Compression Test ◽  
Manufacturing Industry ◽  
Dissimilar Materials ◽  
High Strength Steels ◽  
High Strength ◽  
Ring Compression Test ◽  
Friction Coefficients ◽  
Testing Method ◽  
Ring Compression ◽  
Joining Process

Global competition as well as social and scientific megatrends strongly influence the modern car manufacturing industry. One of the most important approaches is the implementation of lightweight constructions. Therefore, the usage of high performance materials with tailored properties gains importance. For safety-relevant components such as automotive passenger cells it is necessary to minimize deformation to reduce the risk of injury for the vehicle occupants during a car accident. Thus, hot stamped high-strength steels have been established. High-strength and low formability of this kind of materials represent new challenges for joining technologies. One possibility to join high-strength steels is the newly developed shear-clinching technology. Due to the use of a combined cutting and joining process, the connection of dissimilar materials with high difference in strength and formability can be achieved. Further research to ensure process reliability and to improve the strength of the joint is required. One possible approach for this is the numerical investigation of the material flow during the joining process. Therefore, the definition of process parameters for the finite element model is necessary. A big impact on the quality of the results has the accuracy of the used friction values. As established testing methods are not suitable for modeling the rather complex tribological system between the joining partners of the shear-clinching process, an innovative testing method is needed. Studies in the field of sheet-bulk metal forming already demonstrated the applicability of the ring compression test for sheet metals. This paper presents a concept for the adaption of the ring compression test to the specific needs of the investigated shear-clinching process. The numerical identification of the friction coefficients is validated by experimental data and first results are qualified by experimental and simulative shear-clinching joints.

Friction in Hot Forging of Chrome Steel Covered with Oxide Scale Film Generated at Steam Atmosphere

2014 ◽  
Vol 622-623 ◽  
pp. 194-200
Author(s):  
Ryo Matsumoto ◽  
Shohei Harada ◽  
Hiroshi Utsunomiya
Keyword(s):  
Oxide Scale ◽  
Compression Test ◽  
Hot Forging ◽  
Chemical Compositions ◽  
Ring Compression Test ◽  
Chrome Steel ◽  
Air Atmosphere ◽  
Ring Compression ◽  
Plastic Deformation Behavior ◽  
Shear Friction

The hot ring compression test of chrome steel covered with an oxide scale film is carried out to examine the effects of the oxide scale film on the hot forging characteristics. For changing the chemical compositions of the oxide scale, the oxide scale film is generated at air or steam atmosphere. The nominal coefficient of shear friction of the chrome steel covered with the oxide scale film is estimated from the plastic deformation behavior during the ring compression test. The estimated coefficient of shear friction of the chrome steel covered with the oxide scale film is found to be lower than that of the chrome steel without the oxide scale film. Furthermore, the oxide scale generated at steam atmosphere provides lower friction characteristics in comparison with the oxide scale generated at air atmosphere. The mechanism of the reduction of friction with the oxide scale is discussed.

Interfacial Friction of Ceramics at High Temperature Ring-Compression Test

2011 ◽  
Vol 704-705 ◽  
pp. 967-972
Author(s):  
Hui Gai Wang ◽  
Yan Pei Song ◽  
Fei Wang ◽  
Kai Feng Zhang
Keyword(s):  
High Temperature ◽  
Boron Nitride ◽  
Friction Factor ◽  
Compression Test ◽  
Elevated Temperatures ◽  
Interfacial Friction ◽  
Average Pressure ◽  
Compression Tests ◽  
Ring Compression Test ◽  
Ring Compression

Using ring compression tests, the interfacial friction and flow stress of 3Y-TZP/Al2O3 composite at elevated temperatures were investigated. Theoretical calibration curves of the friction factor and the relative average pressure curves for the ring compression tests of 6:3:2 standard rings were drawn based on a velocity field capable of describing the bulge phenomena. The lubricant was the boron nitride (hexagonal). The tests were adopted at temperature range of 1400°C-1600°C. Results indicate that the interfacial friction factor has the value in the range of 0.34-0.49, so that boron nitride lubricant can be used effectively in present temperatures. As two extremely important parameters, the temperature and strain rate have no significant effect on the fraction factor. It is proved reliable that the ring-compression test at 1400°C and even higher is used to evaluate the performance of boron nitride lubricant.

scholarly journals Estimation of friction by using improved calibration curves of ring compression test for hot forging of steel

2017 ◽  
Vol 207 ◽  
pp. 2280-2285 ◽  
Author(s):  
Kazuhito Asai ◽  
Kazuhiko Kitamura ◽  
Nobuki Yukawa ◽  
Nobukazu Hayashi
Keyword(s):  
Compression Test ◽  
Hot Forging ◽  
Ring Compression Test ◽  
Calibration Curves ◽  
Ring Compression

Comparison of Ring Compression Testing to Three Point Bend Testing for Unirradiated ZIRLO Cladding

2015 ◽  
Author(s):  
Paul S. Korinko ◽  
Robert L. Sindelar ◽  
Ronald L. Kesterson
Keyword(s):  
Compression Test ◽  
Water Oxidation ◽  
National Laboratory ◽  
Solubility Limit ◽  
Hydrogen Release ◽  
Compression Tests ◽  
Ring Compression Test ◽  
Controlled Cooling ◽  
Ring Compression ◽  
Point Bend

Safe shipment and storage of nuclear reactor discharged fuel requires an understanding of how the fuel may perform under the various conditions that can be encountered. One specific focus of concern is performance during a shipment drop accident. Tests at Savannah River National Laboratory (SRNL) are being performed to characterize the properties of fuel clad relative to a mechanical accident condition such as a container drop. Unirradiated ZIRLO tubing samples have been charged with a range of hydride levels to simulate actual fuel rod levels. Samples of the hydrogen charged tubes were exposed to a radial hydride growth treatment (RHGT) consisting of heating to 400°C, applying initial hoop stresses of 90 to 170 MPa with controlled cooling and producing hydride precipitates. Initial samples have been tested using both a) ring compression test (RCT) which is shown to be sensitive to radial hydride and b) three-point bend tests which are less sensitive to radial hydride effects. Hydrides are generated in Zirconium based fuel cladding as a result of coolant (water) oxidation of the clad, hydrogen release, and a portion of the released (nascent) hydrogen absorbed into the clad and eventually exceeding the hydrogen solubility limit. The orientation of the hydrides relative to the subsequent normal and accident strains has a significant impact on the failure susceptability. In this study the impacts of stress, temperature and hydrogen levels are evaluated in reference to the propensity for hydride reorientation from the circumferential to the radial orientation. In addition the effects of radial hydrides on the Quasi Ductile Brittle Transition Temperature (DBTT) were measured. The results suggest that a) the severity of the radial hydride impact is related to the hydrogen level-peak temperature combination (for example at a peak drying temperature of 400°C; 800 PPM hydrogen has less of an impact/ less radial hydride fraction than 200 PPM hydrogen for the same thermal history) and b) for critical strains in post drying handling, storage and accident conditions the 3 point bend strain tolerance is less affected by radial hydrides than the conventional ring compression test (the radial hydride related Quasi DBTT associated with a three point bend straining is lower (better) than that measured by the ring compression tests).

Determination of the friction factor of Ti-6Al-4V titanium alloy in hot forging by means of ring-compression test using FEM

2011 ◽  
Vol 44 (12) ◽  
pp. 2074-2080 ◽  
Author(s):  
Yanchun Zhu ◽  
Weidong Zeng ◽  
Xiong Ma ◽  
Qingan Tai ◽  
Zhihua Li ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Friction Factor ◽  
Compression Test ◽  
Hot Forging ◽  
Ring Compression Test ◽  
Ring Compression

Superimposed Oscillating and Non-Oscillating Ring Compression Tests for Sheet-Bulk Metal Forming Technology

2015 ◽  
Vol 794 ◽  
pp. 89-96 ◽  
Author(s):  
S. Koch ◽  
Milan Vucetic ◽  
Sven Hübner ◽  
Anas Bouguecha ◽  
Bernd Arno Behrens
Keyword(s):  
Compression Test ◽  
Metal Forming ◽  
Compression Tests ◽  
Ring Compression Test ◽  
Oscillation System ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Forming Technology ◽  
Water Jet Cutting ◽  
Ring Compression

The new manufacturing technology sheet-bulk metal forming (SBMF) combines the sheet metal forming and bulk metal forming techniques. At the Institute of Forming Technology and Machines (IFUM), a new multistage SBMF process is being developed. In order to reduce the friction and improve the dimensional accuracy of the parts, superimposed oscillation is used within the new SBMF process. SBMF processes allow the manufacturing of solid metal components out of flat steel. To analyse the effect of friction on the superimposed oscillating SBMF process more precisely, superimposed oscillating and non-oscillating ring compression tests at room temperature were carried out. Like the semi-finished products for SBMF process the ring specimens were cut out of a sheet plate by water jet cutting. A new tool system with an integrated hydraulic oscillation system was developed for superimposed oscillating compression of the ring specimens. This tool system enables the absorption of the forming force and displacement stroke of the ring specimen during the ring compression test. After the practical experiments, the force profiles of superimposed oscillating and of non-oscillating process were compared. The influence of the frequency on the surface roughness of ring specimens was investigated. Furthermore, the tribological conditions of the superimposed oscillating ring compression test were analyzed.

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