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In this study, springback of Ti-6Al-4V sheet subjected to hot bending was investigated experimentally and by numerical simulation. The experiment determined the relative effects of forming temperature, forming speed and holding time on springback during hot bending of the alloy sheet. Distribution of temperature and equivalent stress fields experienced during hot bending were predicted by thermal-mechanical coupling numerical simulation. Analysis of the mutual influence of deformation and temperature was conducted using finite element modeling in DYNAFORM software. The results indicated that increased forming temperature, forming speed and holding time each reduced springback to a degree. Forming temperature had the greatest influence in limiting springback, followed by forming speed and holding time, the latter of which was of minor significance. The thermomechanical coupling numerical model is reliable and the predicted temperature field distribution was confirmed. [ABSTRACT FROM AUTHOR]

The deformation and effective die quenching are critical to ensure the final dimensional accuracy and strength of the thick-walled curved components in hot forming-quenching integrated process. The deformation behavior of an Al–Cu–Mg alloy plate during bending-quenching process was thus analyzed at different temperatures and die clearances. The strengthening behavior along thickness and radial directions was evaluated under different heating and die quenching conditions. The strengthening mechanism was revealed by microstructure observation. It is found that the smaller die clearance and higher heating temperature contribute to improve the dimensional accuracy. The water-cooled die quenching can ensure the effective quenching of a bended specimen with 25 mm in thickness, being at the strengthening level of peak aging. And, the effective quenching thickness reaches 50 mm at least. Dynamic recovery is the main restoration mechanism in the integrated process. The hardness reduces while air cooling due to the formation of coarse S precipitates with average size exceeding 750 nm. Finally, a large-size tapered thick plate component with superior dimensional accuracy was successfully fabricated under the guidance of the obtained results.

This work reports a 12.3 inch flexible AMOLED display with small bending radius. Based on its flexible substrate and thin film encapsulation (TFE) advantages, S‐shaped demo and smart cockpit were developed by cold bending technology with minimum bending radius of 100 mm. Moreover, by hot bending forming technique, R245 and R500 demo were obtained. [ABSTRACT FROM AUTHOR]

In the no-load test of the 3# motor in Tangshan compressor station of China–Russia Eastern Gas Pipeline Project before commissioning, the amplitude of exciter end rose rapidly and resulted in the shutdown when the operating speed reached 3 120 r/min.To solve this problem, the vibration analysis system was used to analyze the vibration spectrum of the exciter end.It was determined that the fault was caused by the high load upon the bearing bush at the exciter end, which further led to the high local load or local friction of the exciter rotor, induced the hot bending of rotor, caused the new unbalance, and further resulted in shutdown.Local friction marks was found during removal of the bearing bush, and the above analysis conclusion was verified.Through changing the height of bearing base at the exciter end, the bearing bush load was lowered and the rapid amplitude rise at the exciter end was eliminated.The exciter end was balanced and optimized by vector diagram method to ensure that the vibration at the exciter end can meet the requirements of brushless synchronous machines-500 kVA and larger(API 546-2008).Thereafter, the problem of high vibration at the exciter end of the 3# motor in Tangshan compressor station has been quickly solved, and the safe operation can be ensured.

The multi-layer structure of TiAl-based alloys can meet the demand of having lightweight and high-strength properties at elevated temperature. In this paper, the corrugated-core sandwich structure of a TiAl-based alloy was fabricated by the hot bending/diffusion bonding process. In order to fabricate this structure, the high-temperature tensile property, hot bending behavior, and vacuum diffusion bonding of a Ti-47.5Al-Cr-V alloy were investigated. The flow behavior was evaluated by uniaxial tensile experiment, and the results showed that the alloy exhibited good plasticity at the given conditions, and the maximum elongation reached 200% at 1000 °C at strain rate of 3 × 10−4 s−1. The bending experiments were also performed at temperatures of 950, 1000, and 1050 °C with fillet radii of R = 0, 0.5, and 1 mm, respectively. No micro-/macro-defects developed. The vacuum diffusion bonding of this alloy was also carried out, and the shear bonding strength of bonding joints was measured at room temperature. The maximum shear strength was 398 MPa, and the joint was obtained at 1000 °C/30 MPa/3 h. Combining the bonding interface with the shear strength of different joints, the appropriate bonding pressure and bonding time for diffusion bonding of the TiAl alloy at 1000 °C were 20 MPa and 2 h, respectively. Then, the forming process of the corrugated-core sheet was conducted at 1000 °C with a fillet radius of 1 mm. Finally, the corrugated-core sandwich structure was manufactured under vacuum atmosphere, and the mechanical properties and the interface microstructure were investigated. [ABSTRACT FROM AUTHOR]

Recently, improvement of hybrid and electric vehicle technologies, equipped with batteries, continues to solve energy and environmental problems. Lighter weight and crash safety are required in these vehicles body. In order to meet these requirements, three-dimensional hot bending and direct quench (3DQ) technology, which enables to form hollow tubular automotive parts with a tensile strength of 1470 MPa or over, has been developed. In addition, this technology enables to produce partially quenched automotive parts. In this study, the crash characteristics of 3DQ partially quenched products were investigated as the fundamental research of the design for improving the energy absorption. Main results are as follows: (1) for partially quenched straight products in axial crash test, buckling that occurs at nonquenched portion can be controlled; (2) for the nonquenched conventional and overall-quenched curved products, buckling occurs at the bent portion at the initial stage in axial crash tests, and its energy absorption is low; (3) by optimizing partially quench conditions, buckling occurrence can be controlled; and (4) In this study, the largest energy absorption was obtained from the partially quenched curved product, which was 84.6% larger than the energy absorption of the conventional nonquenched bent product in crash test.

Recently, the usage of thick plate is being increased to replace the forged parts for reducing the weight, forming load as well as improving the tool life in the automotive industry. In this study, a numerical simulation was carried out to find the process conditions which affect the product quality by examining the U-channel shape and the forming capabilities for thick high-strength steel plates. The steel plate used was composed of Nb 0.05%–Ti 0.01%–V 0.07% micro-alloyed high-strength steel with a 580 MPa strength at room temperature. The effect of forming temperature and corner radius of punch on spring-go behavior was investigated, and mechanism of spring-go based on through-thickness stress was found during the bending of thick plate at the elevated temperature. Based on the simulation results, a prediction model of spring-go was constructed, and compensation method of the tool to improve the dimensional accuracy of bent part was suggested. [ABSTRACT FROM AUTHOR]

Proses pembentukan plat baja dalam industri kelautan diketahui bervariasi proses pengerjaannya, tidak hanya pengelasan saja, namun dapat pula konstruksi bending (bengkok). Bending, mempunyai dua variasi metode yaitu hot bending dan cold bending. Untuk mengetahui metode mana yang lebih tepat digunakan pada industri kelautan, dilakukan penelitian dengan menggunakan perbandingan kedua metode bending tersebut menggunakan variasi sudut yakni 90° dan 135°. Masing-masing sudut yang digunakan dibagi menjadi tiga spesimen yang akan mempengaruhi laju korosi pada plat tersebut. Uji laboratorium dengan menggunakan NaCl 2% dilakukan untuk mengetahui berapa laju korosi dari metode hot bending dan metode cold bending. Perhitungan kemudian dilakukan setelah hasil laju korosi didapat, untuk menentukan grafik laju korosi dari variasi bending tersebut. Hasil uji laju korosi pada metode cold bending dengan sudut bending 90° adalah 0,54 mm/year, dan untuk sudut bending 135° adalah 0,32 mm/year. Sedangkan hasil uji laju korosi pada metode hot bending dengan sudut bending 90° adalah 0,53 mm/year, dan untuk sudut bending 135° adalah 0,24 mm/year. Metode cold bending diketahui mempunyai nilai laju korosi lebih besar dibandingkan metode hot bending. Morfologi permukaan spesimen dianalisa dengan menggunakan Scanning Electron Microscopy (SEM). Permukaan spesimen dengan metode cold bending diketahui mengalami perubahan yang cukup besar dibanding spesimen dengan metode hot bending.

The basic properties of Three-Dimensional Hot Bending and Direct Quench (3DQ), especially the property of bending force were researched. The tensile strength of the product reaches 1470 MPa, and the energy absorption in crash test increases by applying partial quenching. In this report, the basic properties of Three-Dimensional Hot Bending and Direct Quench (3DQ), specially the property of bending force, are introduced. In addition, mass production system using robot and features of products are introduced. [ABSTRACT FROM AUTHOR]

The utilization of high-strength steel for automotive structural parts has increased since the oil crisis in the 1970s owing to its high strength and potential for weight reduction. Because of the limited formability of high-strength steels, automotive components are increasingly produced through hot press forming. In some instances, high-strength steel sheets are coated with an Al-Si layer in order to prevent scaling of components during hot press forming, and this can increase their reliability with a view to the dimensional accuracy and stress distribution when they are in service. In this contribution, the coating degradation mechanisms of Al-Si-coated boron steel after the hot bending process are reported. The issues related to coating degradation during hot press forming are critically reviewed at different positions on a part that was subject to hot bending. In addition, the hardness and friction coefficient were tested by a nano-indenter at various positions. The relationship between the experimental parameters and coating layer properties is also reported. It is concluded that the bending deformation affected the coating layer behavior the most. [ABSTRACT FROM AUTHOR]

Bending behavior occurs in the hot press forming process, resulting in many cases of failure during forming. To address the problem of cracking and improve the formability and mechanical properties of boron steel sheets in the bending process, an experiment has been carried out by using a spring compound bending die. Also, a comparison has been made between the traditional U-bending die and the spring compound bending die with regard to formability. The influence of the parameters for hot press forming such as the heating temperature, punch speed, and die radii on the mechanical properties and microstructure was analyzed by tension testing and metallographic observations. [ABSTRACT FROM AUTHOR]