X-ray Peak Profile Analysis on the Microstructure of Al-5.9%Mg-0.3%Sc-0.18%Zr Alloy Deformed by High Pressure Torsion Straining

The microstructure of plastically deformed Al-5.9%Mg-0.3%Sc-0.18%Zr alloy has been investigated. The severe plastic deformation has been performed by high pressure torsion straining (HPT) up to 15 revolutions at room temperature. The microstructure as a function of the number of revolutions is studied by X-ray diffraction peak profile analysis. It is concluded that the HPT technique results in nanostructure even after 0.5 turn with very high dislocation density. The crystallite size decreases and the dislocation density increases with the number of revolutions, however, after five turns they go into saturation. The edge and the dipole character of the dislocation structure becomes stronger with the increase of the number of revolutions. The value of the crystallite size determined by X-ray peak profile analysis is a bit smaller than the grain size obtained by transmission electron microscopy (TEM)

Razvitak intenzivnih plastičnih deformacija (IPD) kontinuiranog procesa za trake i šipkaste proizvode

Grain refinement upon the severe plastic deformation (SPD) at low temperatures (below the recrystallization temperature) and an unusual improvement the properties of such materials are shown reliably. However, the industrial application is limited due to the absence of effective continuous SPD processes. The potential of development of continuous SPD processes based on the equal channel angular pressing (ECAP) process from one side and continuous extrusion or drawing processes from another side is considered. Existing various continuous SPD processes for strip, rod and wire production are analyzed.Usitnjavanje zrna pod utjecajem intenzivnih plastičnih deformacija (IPD) na nižim temperaturama (ispod temperature rekristalizacije) i neuobičajno poboljšavanje svojstava takovih materijala se pokazalo stvarnim. Međutim, industrijska primjena je ograničena glede nedostatka efektivnog kontinuiranog procesa IPD. Razmatraju se mogućnosti razvitka kontinuiranog IPD procesa na temelju s jedne strane na kutno kanalnom prešanju (KKP), a s druge strane na kontinuiranoj ekstruziji ili procesu vučenja. Analiziraja se i postojanje različitih kontinuiranih IPD procesa za traku, šipkaste proizvode i žicu

Ultrafino zrnati niskougljični čelici dobiveni intenzivnom plastičnom deformacijom

The structure and properties of 0,14% C and 0,1% C - B low-carbon steels taken in two initial states, martensitic and ferritic-pearlitic, were studied after cold equal-channel angular (ECA) pressing. ECA pressing leads to the formation of only partially submicrocrystalline structure with a grain size of 150 – 300 nm, depending on the steel alloying and initial state. The finest structure with the elements of 190 nm in size is obtained in the 0,1% C - B steel microalloyed with boron. The strength of the 0,1% C - B steel after cold ECA pressing (Rm = 805-1235 MPa) meets the specifications of fasteners of the R80 - R120 strength grade. The strength of the deformed 0,14% C steel is close to the R80 strength grade.Ultrafino zrnati niskougljični čelici dobiveni intenzivnom plastičnom deformacijom. Struktura i svojstva niskougljičnih čelika sa 0,14%C i 0,1% C-B uzeta u dva početna stanja, martenzitnom i feritno-perlitnom, istraživani su poslije hladnog kutno kanalnog prešanja (KKP). KKP postupak dovodi do stvaranja parcijalne submikrokristalne strukture sa veličinom zrna 150-300nm, ovisno od vrste čelika i početnog stanja. Najfinija struktura sa veličinom zrna 190nm dobijena je za 0,1%C-B čelik (mikrolegiran borom). Vlačna čvrstoća ovog čelika poslije KKP-a (Rm=805-1235 MPa), uvrštava ovaj čelik u kvalitetnu skupinu R80 - R120. Za čelik sa 0,14%C dobijena vlačna čvrstoća ga uvrštava do R80

Nano- and submicrocrystalline steels processed by severe plastic deformation

The aim of this paper is to consider the features of structure evolution during severe plastic deformation (SPD) of steels and its influence on mechanical properties. The investigations have been carried out mainly on low-carbon steels as well as on austenitic stainless steels after SPD by torsion under high pressure (HPT) and equal-channel angular pressing (ECAP). Structure formation dependences on temperature deformation conditions, strain degree, chemical composition, initial state and pressure are considered. The role of phase transformations for additional grain refinement, namely, martensitic transformation, precipitation of carbide particles during SPD and heating is underlined

Obrada metala intenzivnom plastičnom deformacijom (IPD) – odgovarajuća struktura i mehanička svojstva

SPD methods are used to convert coarse grain metals and alloys into ultrafine grained (UFG) materials. Obtained UFG materials then possess improved mechanical and physical properties which destine them for a wide commercial use. This paper, in one direction, looks into historical development of SPD processes and their effect at obtaining fine crystalline structure, and on the other side also partially focuses on development of UFG structure and its stability in commercial pure aluminium as a function of strain and post-deformation annealing applied.Obrada metala intenzivnom plastičnom deformacijom (IPD) – odgovarajuća struktura i mehanička svojstva. IPD je postupak pretvorbe krupno u ultrafino zrnate (UFZ-a) metale i legure. Dobiveni UFZ materijal posjeduje oplemenjena mehanička i fizikalna svojstva, te su namjenjeni za široko komercijalno rabljenje. Ovaj članak s jedne strane daje osvrt na povijesni razvitak IPD-a postupka, a s druge strane djelomice ishodište za razvitak UFZ-a i njezine stabilnosti u trgovački čistom aluminiju, kao funkcija preoblikovanja i poslije deformacije primjenjenog žarenja

Recent Progress in High Strength Low Carbon Steels

Advanced High Strength (AHS) steels, among them especially Dual Phase (DP) steels, Transformation Induced Plasticity (TRIP) steels, Complex Phase (CP) steels, Partially Martensite (PM) steels, feature promising results in the field. Their extraordinary mechanical properties can be tailored and adjusted by alloying and processing. The introduction of steels with a microstructure consisting at least of two different components has led to the enlargement of the strength level without a deterioration of ductility. Furthermore, the development of ultra fine-grained AHS steels and their service performance are reviewed and new techniques are introduced. Various projects have been devoted to develop new materials for flat and long steel products for structural applications. The main stream line is High Strength, in order to match the weight lightening requirements that concern the whole class of load bearing structures and/or steel components and one of the most investigated topics is grain refinement

Mechanical properties, biodegradation, and biocompatibility of ultrafine grained magnesium alloy WE43

In this work, the effect of an ultrafine-grained (UFG) structure obtained by multiaxial deformation (MAD) on the mechanical properties, fatigue strength, biodegradation, and biocompatibility in vivo of the magnesium alloy WE43 was studie

Mehanička i uporabna svojstva niskougljičnih čelika poslije intenzivne plastične deformacije

The structure and properties of the 0,09% C-Mn-Si-Nb-V-Ti, 0,1 %C-Mn-V-Ti and 0,09% C-Mo-V-Nb low-carbon steels were studied after cold equal-channel angular pressing (ECAP). ECAP leads to the formation of partially submicrocrystalline structure with a grain size of 150 – 300 nm. The submicrocrystalline 0,09 %C-Mn-Si-Nb-V-Ti steel compared with the normalized steel is characterized by Re higher more than by a factor of 2 and by the impact toughness higher by a factor of 3,5 at a test temperature of -40°C. The plasticity in this case is somewhat lower. The high-strength state of the submicrocrystalline 0,1% C-Mn-V-Ti and 0,09% C-Mo-V-Nb steels after ECAP is retained up to a test temperature of 500°C. The strength properties at 600°C (i.e. the fire resistance ) of these steels are higher by 20-25 % as compared to those of the undeformed steels. The strength of the 0,09% C-Mo-V-Nb steel at 600°C is substantially higher than that of the 0,1% C-Mn-V-Ti steel.Istražena je struktura i svojstva niskougljičnog čelika 0,09% C-Mn-Si-Nb-V-Ti, 0,1% C-MN-V-Ti i 0,09% C-Mo-V-Nb poslije hladnog kanalno kutnog prešanja (KKP). KKP dovodi do ustroja submikrokristalne strukture s veličinom zrna 150-300 nm. U submikrokristalnom čeliku 0,09% C-Mn-Si-Nb-V-Ti se povećala više od dva puta, a udarna žilavost pri temperaturi ispitivanja -40°C više od tri i pol puta usporedbom s normaliziranom stanju tog čelika. Plastičnost se pri tome nešto smanjuje. Visoka čvrstoća submikrokristalnog čelika 0,1% C-Mn-V-Ti i 0,09% C-Mo-V-Nb zadržava se do temperature ispitivanja 500°C. Vatrootpornost ovih čelika pri 600°C 20-25% je više nego u nedeformiranom stanju. Čvrstoća čelika 0,09% C-Mo-V-Nb pri 600°C je znatno viša nego za čelika 0,1% C-Mn-V-Ti

Effect of multiaxial forging on microstructure and mechanical properties of Mg-0.8Ca alloy

It was shown that multiaxial forging with continuous decrease of temperature from 450°C to 250°C turns coarse structure of the Mg-0.8Ca alloy in homogenized state with grain size of several hundreeds μm into fine structure with average grain size of about 2.1 μm. Refinement of structure is accompanied by drastic increase of mechanical properties: tensile yield strength increases from 50 MPa to 193 MPa, ultimate tensile strength increases from 78 to 308 MPa and elongation to fracture increases from 3.0% to 7.2%. The microstructural evolution during multiaxial forging is studied using optical microscopy, scanning electron microscopy and EBSD analysis. The mechanisms responsible for refinement of microstructure are discusse