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1

Microstructural characterization of ULC steel

Nguyen Cao-Son, Le Hoang, Bui Anh-Hoa

Advances in Materials Science

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2020

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Vol. 20, nr 1(63)

71--81

EN

In the present study, microstructure of the ULC steel was investigated by using the X-ray diffraction (XRD), optical microscopy (OM) and electron back scattering diffraction (EBSD) analysis. The pure ferrite phase consisting of various crystalline orientations, e.g. (110) and (200) etc., existed in the ULC steel. Ultra-fine grains of ferrite were observed in the ND-TD cross-section (⊥ RD), meanwhile, typical lamina were seen in the ND-RD cross-section (// RD) of the steel sheet. Grain size of the annealed steel was observed to be coarser and equiaxed in all direction. According the EBSD results, intensities of the beneficial texture {111}<001> increased in the annealed steel, but weakened in the cross-section that was parallel to rolling direction. Ratio of low-angle grain boundaries (1°< LAGBs < 15°) in the annealed steel was estimated as the higher value (93.1 %) than that in the cold-rolled steel (69.1 %).

2

Friction stir modification of GTA 7075-T6 Al alloy weld joints: EBSD study and microstructural evolutions

Shamanian M., Mostaan H., Safari M., Szpunar J. A.

Archives of Civil and Mechanical Engineering

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2017

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Vol. 17, no. 3

574--585

EN

As known, mechanical properties of gas tungsten arc welded 7075 Al alloys are not desirable and some techniques should be utilized in order to refine the microstructure and hence to improve the mechanical properties of weld joints. In this research work, the microstructure of gas tungsten arc welded 7075 Al alloy was modified by friction stir processing. Evaluation of the tensile strength of the welded joints showed that the tensile strength of the welded joint (228 MPa) increases up to 320 MPa after friction stir processing. In addition, electron backscattered diffractometry (EBSD) was used in order to study the microstructure and grain boundary character evolutions during arc welding and friction stir processing. It was revealed that as-cast dendritic microstructure of gas tungsten arc welded joint completely disappears during friction stir processing and very fine equiaxed grains are formed in welded joints. Analysis of EBSD data showed that friction stir processing of gas tungsten arc welded joints leads to increase of specific boundaries from 0.7% up to 7.8%. In addition, fraction of high angle boundaries increases after friction stir processing which is resulted from dynamic recrystallization occurring during friction stir processing.

3

Optimization of Laboratory Hot Rolling of Brittle Fe-40at.%Al-Zr-B Aluminide

Schindler I., Hadasik E., Kopeček J., Kawulok P., Fabík R., Opěla P., Rusz S., Kawulok R., Jabłońska M.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 3A

1693--1701

EN

Use of the protective steel capsules enabled to manage the laboratory hot flat rolling of the extremely brittle as-cast aluminide Fe-40at.%Al-Zr-B with the total height reduction of almost 70 %. The hot rolling parameters were optimized to obtain the best combination of deformation temperature (from 1160°C up to 1240°C) and rolling speed (from 0.14 m·s−1 to 0.53 m·s−1). The resistance against cracking and refinement of the highly heterogeneous cast microstructure were the main criteria. Both experiments and mathematical simulations based on FEM demonstrated that it is not possible to exploit enhanced plasticity of the investigated alloy at low strain rates in the hot rolling process. The heat flux from the sample to the working rolls is so intensive at low rolling speed that even the protective capsule does not prevent massive appearance of the surface transverse cracking. The homogeneity and size of product’s grain was influenced significantly by temperature of deformation, whereas the effect of rolling speed was relatively negligible. The optimal forming parameters were found as rolling temperature 1200°C and the rolling speed 0.35 m·s-1. The effective technology of the iron aluminide Fe-40at.% Al-Zr-B preparation by simple processes of melting, casting and hot rolling was thus established and optimized.

PL

Zastosowanie ochronnych stalowych kapsuł pozwoliło na przeprowadzenie laboratoryjnego walcowania na gorąco pasm z niezwykle kruchego odlewanego aluminidku żelaza (stopu na osnowie fazy międzymetalicznej) Fe-40at.%Al-Zr-B, które umożliwiło redukcję wysokości o prawie 70%. Parametry walcowania na gorąco były dostosowywane celem uzyskania korzystnego zakresu temperatury odkształcenia (od 1160°C do 1240°C) oraz prędkości walcowania (od 0.14 m·s−1 do 0.53 m·s−1) dla otrzymania pasma bez pęknięć i rozdrobnienia silnie niejednorodnej mikrostruktury odlewu. Zarówno eksperymenty jak i matematyczne symulacje oparte na MES wykazały, że niemożliwe jest uzyskanie dobrej plastyczności badanego stopu przy niskich prędkościach odkształcenia podczas walcowania na gorąco. Strumień ciepła płynący z próbki na walce jest tak intensywny przy małej prędkości walcowania, że nawet kapsuła ochronna nie zapobiega pojawieniu się powierzchniowych pęknięć poprzecznych. Jednorodność i rozmiar ziarn w materiale silnie zależy od temperatury odkształcenia, podczas gdy wpływ prędkości walcowania jest relatywnie niewielki. Optymalne parametry kształtowania stopu to: temperatura 1200°C oraz prędkość walcowania 0.35 m·s−1. Skuteczna technologia przygotowania aluminidku żelaza Fe-40at.%Al-Zr-B w prostym procesie topienia, odlewania i walcowania na gorąco została w ten sposób ustalona i zoptymalizowana.

4

Effect of plastic deformation on the structure and texture of CuSn6 alloy

Kwaśny W., Nuckowski P., Jung T., Rdzawski Z., Głuchowski W.

Czasopismo Techniczne. Mechanika

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2013

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R. 110, z. 1-M

213--219

EN

This paper presents the results of study in the structure and texture CuSn6 alloy deformed in the RCS (repetitive corrugation and straightening) process. Investigated the influence of process parameters on the above property. The obtained results were correlated with the results of the alloy subjected to cold rolling.

PL

W artykule przedstawiono wyniki badań struktury oraz tekstury stopu CuSn6 odkształconego w procesie RCS (cykliczne gięcie i prostowanie). Określono wpływ parametrów procesu na wyżej wymienione własności. Uzyskane rezultaty skorelowano z wynikami badań stopu poddanego walcowaniu na zimno.