A Comparative Study on the Hot Deformation Behavior of As-Cast and Twin-Roll Cast Mg-6.8Y-2.5Zn-0.4Zr Alloy

Kittner, Kristina; Ullmann, Madlen; Prahl, Ulrich

doi:10.3390/ma14133628

Cited by 5 publications

(3 citation statements)

References 41 publications

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“…The Arrhenius-type constitutive equation [ 28 , 29 ] is used to describe the deformation process of the alloy, which can better predict the ability of the hot deformation and the microstructure evolution of the NiTi alloy. The α, n and Q are calculated through bringing the peak-stress into Equations (6) and (9), which is 0.00928, 3.7168 and 272.69 KJ/mol respectively.…”

Section: Resultsmentioning

confidence: 99%

Research on the Hot Deformation Behavior of the Casting NiTi Alloy

et al. 2021

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The hot deformation behavior and processing maps of the casting NiTi alloy were studied at the deformation temperature of 650–1050 °C and the strain rate of 5 × 10−3–1 s−1 by Gleeble-3800 thermal simulating tester. The variation of the strain rate sensitivity exponent m and the activation energy Q under different deformation conditions (T = 650–1050 °C, ε˙ = 0.005–1 s−1) were obtained. The formability of the NiTi alloy was the best from 800 °C to 950 °C. The constitutive equation of the casting NiTi alloy was constructed by the Arrhenius model. The processing map of the casting NiTi alloy was plotted according to the dynamic material model (DMM) based on the Prasad instability criterion. The optimal processing areas were at 800–950 °C and 0.005–0.05 s−1. The microstructure of the casting NiTi alloy was analyzed by TEM, SEM and EBSD. The softening mechanisms of the casting NiTi alloy were mainly dynamic recrystallization of the Ti2Ni phase and the nucleation and growth of fine martensite.

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Section: Resultsmentioning

confidence: 99%

Research on the Hot Deformation Behavior of the Casting NiTi Alloy

et al. 2021

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“…Mg alloys are synthesized by various processing routes, such as DMD (Direct Metal Deposition), SLM (Selective Laser Melting), casting, and powder metallurgy [12,14]. In the cast processing route, the defects (porosity, shrinkage, hot tears, and segregations), material wastages, and the fact that molten magnesium is more prone to oxidation and burn limit the extensive use of casting processes [15,16]. Secondary processing methods (such as plastic deformation and heat treatment methods) are applied to the cast products to limit the casting defects and enhance the product's properties [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Image Processing of Mg-Al-Sn Alloy Microstructures for Determining Phase Ratios and Grain Size and Correction with Manual Measurement

et al. 2021

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The study of microstructures for the accurate control of material properties is of industrial relevance. Identification and characterization of microstructural properties by manual measurement are often slow, labour intensive, and have a lack of repeatability. In the present work, the intermetallic phase ratio and grain size in the microstructure of known Mg-Sn-Al alloys were measured by computer vision (CV) technology. New Mg (Magnesium) alloys with different alloying element contents were selected as the work materials. Mg alloys (Mg-Al-Sn) were produced using the hot-pressing powder metallurgy technique. The alloys were sintered at 620 °C under 50 MPa pressure in an argon gas atmosphere. Scanning electron microscopy (SEM) images were taken for all the fabricated alloys (three alloys: Mg-7Al-5Sn, Mg-8Al-5Sn, Mg-9Al-5Sn). From the SEM images, the grain size was counted manually and automatically with the application of CV technology. The obtained results were evaluated by correcting automated grain counting procedures with manual measurements. The accuracy of the automated counting technique for determining the grain count exceeded 92% compared to the manual counting procedure. In addition, ASTM (American Society for Testing and Materials) grain sizes were accurately calculated (approximately 99% accuracy) according to the determined grain counts in the SEM images. Hence, a successful approach was proposed by calculating the ASTM grain sizes of each alloy with respect to manual and automated counting methods. The intermetallic phases (Mg17Al12 and Mg2Sn) were also detected by theoretical calculations and automated measurements. The accuracy of automated measurements for Mg17Al12 and Mg2Sn intermetallic phases were over 95% and 97%, respectively. The proposed automatic image processing technique can be used as a tool to track and analyse the grain and intermetallic phases of the microstructure of other alloys such as AZ31 and AZ91 magnesium alloys, aluminium, titanium, and Co alloys.

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“…Individual flow stress curves of the studied steels were mathematically described using the Cingara and McQueen model. Kittner, Ullmann, and Ulrich [ 4 ] performed a comparative study on the hot deformation behavior of as-cast and twin-roll cast (TRC) Mg-6.8Y-2.5Zn-0.4Zr alloy. TRC resulted in a finer microstructure.…”

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confidence: 99%