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Using neural networks to predict the low curves and processing maps of TNM-B1

Stendal Johan Andreas, Emdadi Aliakbar, Sizova Irina, Bambach Markus

Computer Methods in Materials Science

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2018

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Vol. 18, No. 4

134--142

EN

The ability to predict the behavior of a material is vital in both science and engineering. Traditionally, this task has been carried out using physics-based mathematical modeling. However, material behavior is dependent on a wide range of interconnected phenomena, properties and conditions. During deformation processes, work hardening, softening, microstructure evolution and generation of heat all occur simultaneously, and can either cooperate or compete. In addition, they can vary with the deformation temperature, applied force and process speed. As the complete picture of material behavior from the macroscopic scale to the atomic scale is not yet fully understood, deformation processes such as hot forging can be difficult to handle using physics-based modeling. Usually, modeling the high temperature deformation behavior of metals consists of extracting characteristic points from the experimental flow curve data, and use them to fit the model equations through regression analysis. This is called phenomenological modeling, as it is based on the observations of a phenomena rather than being derived from fundamental theory. Alternatively, the data obtained from experiments could be used for a data-driven or machine learning (ML) approach to model the material behavior. An ML model would require no knowledge of the underlying physical phenomena governing a deformation process, as it can learn a mapping function which connects input to output based purely on the experimental data. In this work, the application of machine learning to modeling the flow curves of two different states of the titanium aluminide (TiAl) TNM-B1; hot isostatically pressed (HIPed) and heat treated, is investigated. Neural networks were used to learn a mapping function which predicted flow stress based on the inputs temperature, strain and strain rate. In addition, strain rate sensitivity maps and processing maps based on the experimental and the predicted data are analysed and compared. The results revealed that the neural networks were able to produce realistic and accurate flow curves, which fitted to the underlying behavior of the experimental data rather than the noise. The strain rate sensitivity and processing maps showed conflicting results. Good correlation was found for the HIPed material state between the ones based on experimental data and the ones based on predicted values, while there was a significant difference for the heat treated state.

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Theoretical-Experimental Analysis of the Workability of the Ni50Cr45N0.6 alloy

Łukaszek-Sołek A., Świątoniowski A., Celadyn K., Sińczak J.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 1

59--65

EN

In this paper, the results of investigations into, and of the analyses of, the hot deformation behaviour of the Ni50Cr45N0.6 alloy were presented. Compression tests were conducted on a Gleeble 3800 thermo-mechanical simulator within the following temperatures range 850-1200°C and within that of the strain rate 1-40 s-1 to the constant true strain of 0.9, for the purpose of fulfilling the objective of obtaining experimental stress date. Those data were taken advantage of for the purpose of calculating the workability parameters, and that means the efficiency of power dissipation η, the flow instability ξ and the strain rate sensitivity m. The processing maps based upon Murty’s criterion were drawn up for the following true strain range: 0.2-0.9, and, subsequently, both processing windows and the flow instability areas were determined. For the alloy being analysed, the most advantageous conditions of metal forming were ascertained within the following range of temperatures: 950-1000°C, and for that of the strain rate amounting to 10-40 s-1, and that because of (occurring at the temperature of 950°C) the peak of the efficiency of power dissipation parameter η, amounting to 22% (in accordance with Murty’s criterion). The flow instability areas identified on the processing maps ought to be avoided in metal forming processes. Experimental rolling tests were also conducted.

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Effect of Processing Conditions on Forgeability and Properties of Hot and Warm-Forged Steel 300M

Skubisz P., Łukaszek-Sołek A.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 4

2247--2254

EN

Results of investigation of the effect of processing conditions of medium-carbon alloy steel AISI 300M on forgeability and microstructure-properties are presented here, including as-forged and heat treated condition of the material. The presented results concern two vital aspects of plastic forming of high-duty impression-die forgings, which underlay a selection of technological conditions which enable the accomplishment of the required quality of the forged part. These are: firstly, the microstructure and mechanical properties and their uniformity within a part and secondly, technological realization of forging the required geometry in the given processing conditions. In order to define a favourable processing window, dynamic behaviour modeling in variable forging conditions was carried out, establishing a coefficient of energy dissipation η% and the metal flow instability areas, which indicated the temperature regime and strain rate range for the forging process. The constructed processing maps were subject to experimental verification in the die-forging tests, carried out on a screw press. Hot and warm forging conditions were applied accordingly to selected areas of the processing maps, representative for unique forging conditions occurring in the industrial practice.

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Mapy efektywności przeróbki plastycznej stopu Fe-16Al

Łyszkowski R., Bystrzycki J.

Hutnik, Wiadomości Hutnicze

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2008

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Vol. 75, nr 11

663-667

PL

W pracy przedstawiono wyniki badań odkształcenia plastycznego stopu na osnowie nieuporządkowanego roztworu stałego Al w Fe�. Badania symulacyjne ściskania jednoosiowego przeprowadzono w temperaturze 600-1100 stopni C z szybkością odkształcenia 0,001-100 s-1 do stałej wartości odkształcenia rzeczywistego 0,6. Na podstawie uzyskanych krzywych naprężenie odkształcenie obliczono wartości współczynnika efektywności procesu dyssypacji mocy ni opracowano mapy efektywności obróbki plastycznej. Uzyskane wyniki skorelowano z badaniami mikrostruktury stopu. Badany stop wykazuje optimum podatności na obróbki plastycznej w temperaturze powyżej 800 stopni C i przy szybkości odkształcenia poniżej 0,5 s-1, osiągając maksimum dyssypacji mocy wynoszące 56 %. W obszarze objętym tymi parametrami, materiału podlega procesom zdrowienia i rekrystalizacji dynamicznej, prowadzącym do powstania struktury drobnoziarnistej. Materiał wykazuje również obszar niestabilności płynięcia w temperaturze poniżej 700 stopni C. Wzrost temperatury powyżej 1000 stopni C dla szybkości odkształcenia poniżej 0,01 s-1 skutkuje rozrostem ziarna.

EN

Deformation behaviour of disordered solid solution Al in Fe� under hot compression conditions was characterized in the temperature range 600-1100 degree C and the strain rate range 0.001-100 s using processing maps. At strain rates below 0.5 s-1 and temperatures above 800 degree C, the material exhibited optimum workability with maximum efficiency of power dissipation about 56 %. Then, the material undergoes dynamic recovery and recrystallization to produce a fine-grained microstructure. The material shows also an unstability flow zone at temperature below 700 degree C. The temperature rise above 1000 degree C at strain rates below 0,01 -1s causes grain growth.

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Opracowanie map procesów obróbki cieplno-plastycznej metali i stopów

Kuziak R., Zalecki W., Molenda R., Łapczyński Z.

Prace Instytutu Metalurgii Żelaza

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2005

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T. 57, nr 4

1-6

PL

Celem pracy było opracowanie map procesu obróbki plastycznej na przykładzie miedzi chromowej pozwalającej na dobranie wstępnych warunków kucia odkuwek osiowosymetrycznych z tego materiału. Mapy procesu opracowano na podstawie wyników analizy prób osiowo-symetrycznego ściskania. Zbadano mikrostrukturę oraz twardość próbek odkształconych. W oparciu o przeprowadzone badania symulacyjne, w firmie Zakład Obróbki Plastycznej Sp. z o.o. w Świdniku przeprowadzono przemysłową próbę kucia matrycowego odkuwki osiowosymetrycznej. Próby przemysłowe dały wynik pozytywny.

EN

The purpose of this paper is to develop the thermomechanical processing maps for alloy chromium copper alloy, which allows selection of preconditions for forging of axially-symmetrical pieces of this material. The process maps were developed based on results of an axially symmetrical compression test. Microstructure and hardness of deformed samples was examined. On the basis of simulation tests, the industrial tests of die forging of axially symmetrical pieces were carried out in Zakład Obróbki Plastycznej Sp. z o.o. in Świdnik, Poland. The industrial tests were successful.