In recent years Russian specialists have developed industrial weldable aluminum alloys alloyed with a small amount of scandium. Scandium added to existing weldable aluminum alloys improves considerably the set of their operational properties. In addition, the presence of scandium makes it possible to create new materials superior to traditional aluminum alloys. The present paper is devoted to problems of simultaneous alloying of aluminum alloys with scandium and zirconium.New" alloys with scandium additives can be divided into four groups in accordance with the system on which the alloys are based, namely: (1) weldable alloys based on the AI -Mg system and not strengthened thermally; (2) thermally strengthened high-strength weldable alloys based on the AI-Zn-Mg system; (3) thermally strengthened weldable alloys of intermediate or high strength that are based on the AI -Li system; (4) thermally strengthened high-strength aircrat~ alloys based on the AI -Zn -Mg -Cu system.Weldable AI -Mg alloys not strengthened thermally and alloyed with scandium have higher strength parameters than the base metal and stronger welded joints than their industrial scandium-free counterparts (see Table I).A comparative analysis of the properties of alloys with the same content of magnesium showed that the addition of scandium increases considerably the parameters o b (by 80-120N/ram 2) and o02 (by 150-170N/ram 2) of annealed sheets and the parameter o b of welded joints (by 70 -150 N/ram2).High-strength thermally strengthened weldable alloys based on the AI-Zn-Mg system with an addition of scandium are also alloyed with a small amount of copper (0.3 -0.5%), which improves considerably the resistance of the base metal and especially that of welded joints to corrosion cracking and slow disruption. It should be noted that the presence of copper intensifies the formation of hot cracks in welding of aluminum alloys. This drawback is eliminated by the introduction of a combined scandium, zirconium, and titanium additive. Two alloys in the AI-Zn-Mg system with scandium and copper additives have been developed, namely, All-Russia Institute of Light Alloys. 01970 (AI -5.4% Zn -2.0% Mg -0.3% Mn -0.35% Cu -0.25% Sc -0.1% Zr) and 01975 (AI -5.4% Zn -2.0% Mg -0.3% Mn -0.25% Cu -0.08% Sc -0.1% Zr). Semiproducts from these alloys have a strength of the base metal a b = 500 N/mm 2 and of welded joints without heat treatment (3-month aging aff~r the welding) a~' = 450 N/ram 2. The safe level of stresses in welded joints of alloys 01970 and 01975, which characterizes the corrosion resistance under stress and the resistance to slow disruption, is rather high (a~ = 225 and 200 N/mm 2, respectively). In addition to the high strength and resistance to corrosion under stress, the alloys are characterized by a high crack resistance and a low anisotropy of the properties.Advanced weldable alloys with scandium additives have been developed in the AI-Li-Mg system, namely, 01421 (AI-5.5% Mg-9.0% Li-0.2% Sc-0.1% Zr), and in the A! -Li -Cu system, namely, 01460 (A...

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669.715'793Commercial weldable aluminum alloys additionally containing scandium have recently been developed in Russia: thermally nonhardening alloys based on the system AI-Mg (01570, 01523, 01515), and thermally hardening alloys based on the systems Al-Zn-Mg (01970, 01975) and AI-Mg-Li (01421, 01423 In our previous studies [1, 2] it has been shown that alloying aluminum with scandium is promising. This work is a continuation of these studies.Continuous casting was used to prepare ingots 134 mm in diameter from six melts in which the scandium content was varied from 0 to 0.6%. Aluminum A99 and scandium in the form of an A1-2% Sc master alloy were used. Ingots were homogenized and pressed into strips with a cross section of 3 x 100 mm. Some of the pressed strips were cold rolled with = 73% without intermediate annealing into sheet 0.8 mm thick. A study of the macr.o-and microstructure of ingots showed that with an increase in scandium content to 0.4% the average grain size (day) is almost unchanged in an ingot. Thus, in ingots of alloys containing 0% and 0.4% scandium, dav = 120 and 110/zm, respectively. With a further increase in scandium content there is clear grain refinement. In an ingot with 0.6% Sc the day = 22/zm. Here ingots had a clearly defined nondendrititic structure. This nature of change in grain size in an ingot depending on scandium content is in good agreement with the phase equilibrium diagram for A1-Sc. According to work in [3][4][5] scandium and aluminum form a diagram of the eutectic type with limiting solubility. The eutectic point corresponds to alloys containing about 0.5 % Sc. With solidification of hypoeutectic alloys first there is precipitation of crystals in a solid solution of scandium in aluminum and the modifying effect of scandium is not observed. With solidification of hypereutectic alloys the f'trst to solidify is A13Sc particles which are active centers for the generation of new grains of solid solution.In view of this in hypereutectic alloys (containing more than 0.5% Sc) there is marked ref'mement of cast grains up to formation of a nondendritic structure. The results obtained agree qualitatively with data obtained in [6].A study of the structure of pressed strips and rolled sheet showed that introduction and an increase in the content of scandium promotes a sharp increase in the thermal stability of the unrecrystallized structure (Fig. 1). Alloy without scandium after pressing had an entirely recrystallized structure, i.e. the recrystallization temperature was below the pressing temperature (tde f = 350°C). Introduction of only 0.1% Sc increased the recrystallization temperature to 535 °C (degree of recrystallization 50%), 0.2% increased it to 570°C, and 0.4% Sc increased it to 610°C. Scandium has an even stronger effect on the recrystallization temperature of cold-rolled sheet. An increase in scandium content from 0 to 0.6% increases the recrystallization All-Union Institute of Light Alloys.

This work investigates a ferrite matrix with multiple non-metallic inclusions to evaluate their influence on the global and local deformation and damage behavior of modified 16MnCrS5 steel. For this purpose, appropriate specimens are prepared and polished. The EBSD technique is used to record local phase and orientation data, then analyze and identify the size and type of inclusions present in the material. The EBSD data are then used to run full phase crystal plasticity simulations using DAMASK-calibrated material model parameters. The qualitative and quantitative analysis of these full phase simulations provides a detailed insight into how the distribution of non-metallic inclusions within the ferrite matrix affects the local stress, strain, and damage behavior. In situ tensile tests are carried out on specially prepared miniature dog-bone-shaped notched specimens in ZEISS Gemini 450 scanning electron microscope with a Kammrath and Weiss tensile test stage. By adopting an optimized scheme, tensile tests are carried out, and local images around one large and several small MnS inclusions are taken at incremental strain values. These images are then processed using VEDDAC, a digital image correlation-based microstrain measurement tool. The damage initiation around several inclusions is recorded during the in situ tensile tests, and damage initiation, propagation, and strain localization are analyzed. The experimental results validate the simulation outcomes, providing deeper insight into the experimentally observed trends.

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