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1

Influence of alloying systems on the lattice parameters of nickel-based superalloys

Glotka O., Ol'shanetskii V., Byelikov S., Fasol Y.

Archives of Materials Science and Engineering

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2023

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Vol. 122, nr 1

5--12

EN

Purpose: The work aims to establish the relationship between the chemical composition, mechanical properties and dimensional mismatch of crystal lattices of heat-resistant nickel alloys. Design/methodology/approach: The results of experimental and calculated data formed based on experimental and taken from open sources results are presented. The XRD method used Bragg-Brentano determined the phase composition, focusing on a RIGAKU MINIFLEX 600 diffractometer (CoKα-radiation). After heat treatment, strength characteristics were determined on cylindrical samples with a working part (diameter 5 mm, length 25 mm). Testing of the alloy for short-term strength was carried out on samples at a temperature of 20°C on UME-10TM and GCM-20 tensile machines. Alloy tests for long-term strength were carried out on similar samples at a temperature of 1000°C on AIMA-5-2 and ZTZ 3/3 machines by uniaxial stretching under a constant load based on 100 hours. Findings: It has been established that with an increase in the value of the mismatch of crystal lattices, the strength of the alloys decreases due to significant internal stresses. It was revealed that for alloys of equiaxed and directional crystallisation, an extremum is observed at a value of 1.5 ... 1.6 K; this is associated with a decrease in the number of elements in the ϒ-solid solution. Research limitations/implications: An essential problem is predicting the structure and properties of heat-resistant alloys without or with a minimum number of experiments. The results of comparative tests of the XDR method and calculated data are analysed. Practical implications: The obtained dependences can be used both for designing new heat-resistant alloys and for improving the compositions of industrial alloys. Originality/value: The value of this work lies in the fact that the dependences of the influence of alloying elements on the mechanical properties and the dimensional mismatch of crystal lattices were obtained, which made it possible to determine the properties without conducting experiments. It has been established that changes in the course of the relationship closely correlate with the processes taking place in the structure of alloys.

2

Comparison of Molding Sand Technology Between Alphaset (APNB) and Furan (FNB)

Ghosh Dipak K.

Archives of Foundry Engineering

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2019

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iss. 4

11--20

EN

The paper focuses on investigation of properties of two most widely used self-set sand binder systems APNB and FNB across the Globe, for making molds and cores in foundries to produce castings of different sizes involving wide range of metals and alloys, ferrous and nonferrous. This includes study of compression strength values of samples made out of molding sand at different binder addition level using new, mechanically reclaimed (MR) and thermally reclaimed (TR) sand. Strength values studied include dry strength (at room temperature) at specified intervals simulating different stages of mold handling, namely stripping and pre heating, followed by degraded strength after application of thinner based zircon wash by brush, subsequent lighting of, then checking strength both in warm (degraded strength) & cold (recovered strength) conditions. Throughout the cycle of mold movement from stripping to knock out, strength requirements can be divided into two broad classifications, one from stripping to closing (dry strength) and another from pouring to knock out (hot & retained strength). Although the process for checking of dry strength are well documented, no method using simple equipments for checking hot & retained strength are documented in literature. Attempts have been made in this paper to use some simple methods to standardize process for checking high strength properties using ordinary laboratory equipments. Temperature of 450°C has been chosen by trial & error method to study high temperature properties to get consistent & amplified values. Volume of gases generated for both binders in laboratory at 850°C have also been measured. Nature of gases including harmful BTEX and PAH generated on pyrolysis of FNB and APNB bonded sands are already documented in a publication [1]. This exercise has once again been repeated in same laboratory, AGH University, Poland with latest binder formulations in use in two foundries in India.

3

Polymer matrix composite laminate under hygrothermal exposure

Kormaníková E.

Roczniki Inżynierii Budowlanej

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2016

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z. 16

49--54

EN

The static load model of laminate with the hygrothermal load is considered in the paper. The corresponding ply properties are calculated using Mori-Tanaka method. A parametric study is conducted by varying the fiber volume fraction in one laminate layer and the fiber orientation of the angle plies in the laminate. The internal forces of laminate plate with symmetric and unsymmetric stacking of layers are investigated.

4

Non-isothermal annealing of AA7075 aluminum alloy - structural and mechanical effects

Pieła K., Błaż L., Sierpiński Z., Foryś T.

Archives of Metallurgy and Materials

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2012

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Vol. 57, iss. 3

703-709

EN

Calorimetric and dilatometric tests were performed on AA7075 aluminum alloy annealed at constant heating rate of 15 degree Celsjus/min in temperature range 20-470 degree Celsjus and discussed in relation to the hardness test and structure observation results. The samples were machined from furnace cooled material (FC), furnace cooled and deformed (FCD) material, solution treated (ST) material and solution treated and deformed (STD) material. It was found that the nucleation and growth of transition η and stable η (MgZn2) phases caused remarkable reduction of thermal expansion coefficient αt , whereas both the dissolution of phase and formation of GP zones were accompanied by an increase of αt value. While η phase started to dissolve at 250 degree Celsjus, a widespread endothermic effect was observed on DSC curves. Dissolution of η particles at high annealing temperatures was accompanied by the solid solution hardening of the alloy. Mentioned hardening process was overlapped by expected material softening that was ascribed to recovery and recrystallization processes. Because of superposition the solution hardening and recrystallization softening, recrystallization temperature could not be precisely defined on the basis of simple hardness measurements.

PL

W pracy przedstawiono wyniki badań kalorymetrycznych, dylatometrycznych i pomiarów twardości stopu aluminium AA7075 poddanego nieizotermicznemu wyżarzaniu (nagrzewaniu ze stała prędkością) w zakresie temperatur 20-470 stopni Celsjusza. Badania objęły cztery stany metalurgiczne materiału: wolno studzony z piecem (FC), wolno studzony z piecem i odkształcony (FCD), przesycony (ST) oraz przesycony i odkształcony (STD). Stwierdzono, ze wydzielanie fazy pośredniej η' i równowagowej η(MgZn2) powoduje wyraźne obniżenie współczynnika rozszerzalności cieplnej αt , natomiast zarówno rozpuszczanie fazy η, jak i formowanie stref GP prowadzi do jego wzrostu. Rozpuszczanie fazy η rozpoczyna sie w temperaturze 250 stopni Celsjusza i towarzyszy mu rozległy efekt endotermiczny, a w zaawansowanym stadium rozpuszczania η także wzrost twardości przesycanych próbek, będący rezultatem umocnienia roztworowego stopu. Umocnienie roztworowe zakłóca tym samym efekt oczekiwanego mięknięcia materiału wskutek rekrystalizacji, co w konsekwencji utrudnia dokładna ocenę temperaturowego zakresu rekrystalizacji w oparciu o pomiary twardości.

5

Zalety i ograniczenia procesu borowania stali.

Przybyłowicz K.

Inżynieria Materiałowa

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1999

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R. XX, nr 5

251-254

PL

Borowanie stali stwarza duże możliwości zwiększenia żywotności narzędzi i elementów maszyn, jednak w literaturze podawane są bardzo duże rozbieżności co do efektów tego procesu (wzrosty żywotności w granicach 1,5 do 12 razy). Oprócz dużej twardości i odporności na ścieranie warstwy borkowe mają znaczną odporność antykorozyjną, na utlenianie i rozpuszczanie w metalach i kwasoodporność, są jednak niekiedy kruche. Wszystkie wymienione właściwości są uzależnione od metody i parametrów procesu borowania, ale i od sposobu badania i składu stali. Dlatego ważną sprawą jest optymalizacja w doborze właściwej metody i parametrów procesu, a także dla uzyskania porównywalnych wyników zużycia , unifikacja metod badania. Celem referatu jest dostarczenie informacji pozwalających na wybór najbardziej odpowiedniej metody i parametrów procesu do danego sposobu zużycia, a także właściwej obróbki cieplnej i sposobu badania własności warstw borkowych.

EN

Boronizing of steels enables to increase the durability of tools and machine parts. There are however divergent data in literature, regarding the effects of this treatment (part life time increase by 1,5-12 times). Apart from the high hardness and wear resistance, boronized layers are heat, acid, and corrosion resistant. Also the boronized material shows lower solubility in melted metals. The basic fault of boronized layers is their brittleness. All mentioned properties depend on the method and parameters of boronizing process and chemical composition of steel and the investigation technique. So the chief problem considering the investigation results is proper optimization of method and process parameters selection as well as unification of investigation procedures. The aim of this paper is to provide the information allowing for the proper choice of the boronizing method and process parameters for particular mechanism of wear, together with the best heat treatment and the method of properties examination.