Wyniki wyszukiwania - Biblioteka Nauki

1

Gradient Materials on Aluminium Alloy Basis Obtained from Powders by Hot Forming

100%

Szczepanik S.

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tom Vol. 28, nr 3-4

602-605

EN

The paper deals with the manufacturing of multi-layer and gradient materials from aluminium and aluminium alloys. The materials were prepared by hot closed-die forging, extrusion and hot consolidation. The formability of multilayer materials was studied at 400°C at the strain rate of 1 s'. The multilayer preforms and preforms with a continuous gradient of chemical composition were closed-die forged and extruded at the temperature of 500°C. The magnitude of extrusion forces and the mechanical properties in tensile, bending and compression tests of obtained materials was examined. The possibility of manufacturing of a sample with gradient chemical composition by hot consolidation was tested.

PL

W pracy podjęto badania nad wytwarzaniem materiałów wielowarstwowych i gradientowych z aluminium i jego stopów. Materiały wytworzono przez odkształcanie na gorąco w procesie kucia w matrycach zamkniętych, wyciskania lub zagęszczania. Odkształcalność materiałów badano w temperaturze 400°C przy prędkości odkształcenia ls"1. Próbki z materiałów wielowarstwowych lub z ciągłym gradientem składu chemicznego odkształcano w matrycach zamkniętych lub wyciskano w temperaturze 500°C. Badano wielkość sił wyciskania i własności mechaniczne w próbie rozciągania, zginania lub ściskania otrzymanych materiałów. Wykazano możliwość wytwarzania wyrobów z gradientem składu chemicznego w połączeniu metod metalurgii proszków i przeróbki plastycznej.

2

Effects of manufacturing methods and production routes on residual stresses of rectangular and square hollow steel sections: a review

72%

Abathun M. Z. , Han J. , Yu W.

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tom Vol. 21, no. 3

246--264

EN

Rectangular and square hollow steel sections can be manufactured using either a “direct forming” or an “indirect forming” method. The production route for both “direct forming” and “indirect forming” techniques can be conducted at room temperature (cold forming) or elevated temperature (hot forming). It might also start by forming at room temperature and subsequently followed by heat treatment (hot-finishing). The manufacturing method and production route choice cause the final products that are roll-formed from the same material to possess different mechanical properties. One of the main reasons for the disparity of mechanical properties is the variation of residual stress induced during forming processes. In this paper, available numerical and experimental studies of different rectangular and square steel hollow sections manufacturing methods and production routes on residual stresses are comprehensively reviewed. Furthermore, studies on the effects of roll-forming parameters on product quality and residual stresses are integrated. Moreover, future research activities aiming to manufacture residual stresses-free rectangular and square hollow sections are recommended.

3

The Influence of the Content of Furfuryl Alcohol Monomer on the Process of Moulding Sand's Thermal Destruction

72%

Dobosz S. M. , Drożyński D. , Jakubski J. , Major-Gabryś K.

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tom Vol. 59, iss. 3

1093--1096

EN

The article discusses the issue of the influence of furfuryl alcohol content in resin binders on properties of moulding sand at elevated temperature. Reducing the share of this component - due to the requirements of the European Union regarding its toxicity - may cause a decrease in temperature of moulding sands’ destruction and, consequently, the thermal deformation of moulds and the creation of many casting defects. The study examined the impact of the furfuryl alcohol content of the thermal destruction processes and on the strength of the moulding sand at an ambient temperature and the tendency to thermal deformation.

PL

W artykule omówiono zagadnienie wpływu zawartości alkoholu furfurylowego w spoiwach żywicznych na właściwości mas formierskich w podwyższonej temperaturze. Zmniejszenie udziału tego składnika – spowodowane wymaganiami Unii Europejskiej odnośnie jego toksyczności – może powodować obniżenie temperatur destrukcji masy, a w konsekwencji deformację cieplną form i powstanie wielu wad odlewniczych. W pracy przebadano wpływ zawartości alkoholu furfurylowego na procesy cieplnej destrukcji spoiwa a także na wytrzymałość masy w temperaturze otoczenia oraz skłonność do deformacji cieplnej.

4

Bi-axial stress state hot bulging behavior and plane-stress visco-plastic material modelling of TA32 sheets

72%

Peng H. , Luo Z. , Qu S. , Shi W. , Fu K. , Xiao W. , Zheng K.

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tom Vol. 23, no. 3

art. no e167, 2023

EN

Bi-axial state is the dominant stress state experienced by the sheet metal during various forming processes, which requires a thorough understanding and modelling for process designs. In this paper, effects of equal bi-axial stress-state on the hot deformation behavior of titanium alloys are thoroughly investigated using hot bulging tests, and is further compared to the uniaxial stress state. Firstly, a specific hot bulging test device enabling a uniform temperature field and constant control of strain rate was established, using which, systematic hot bulging tests at various temperatures (750–850 °C) and strain rates (0.001–0.1 s−1) of the near-alpha phase TA32 sheets were conducted to determine the hot equal bi-axial bulging behavior. Based on the testing data of force and geometry variations of bulged domes, the equivalent stress–strain curves were calculated. Secondly, a plane-stress visco-plastic plane-stress model of near-alpha TA32 sheets was developed for the first time, enabling both the uniaxial and biaxial flow behavior and forming limits to be precisely predicted. The prediction accuracies for uniaxial and biaxial cases are 93.5% and 89%, respectively. In the end, the uniform deformation resulting from the strain and strain rate hardening was determined, which contributes to the understanding of the stress-state effect on hardening preliminarily. The plane stress visco-plastic model provides an efficient and reliable material model for finite element (FE) simulations of hot forming titanium alloy sheets.