Combination of processes and combined solutions in improving the technique and technology of arc welding and fusion

In work systematized and considered on the row of examples basic types of combinations of influences and combination of processes which are developed for the use in the arc welding and naplavke a fluxible electrode. It is shown that new technical and technological effects at welding and naplavke can be got only at purposeful introduction to the technological process of additional influence

ИССЛЕДОВАНИЕ ИЗНАШИВАНИЯ СТАЛЕЙ ПРИ НИЗКИХ СКОРОСТЯХ СКОЛЬЖЕНИЯ ПО АБРАЗИВУ

The abrasive wear tests with sliding speed in the range of 0,1–86,0 mm/s is fulfilled for carbon steels with different structure. It is found that the reduction of sliding speed from tens mm/sec to a few millimeters per second has different influence upon wear of the samples with different type of structure. The most significant increase of wear is attributed to the samples with ferritic structure. When the sliding speed decreases from 86,0 to 5 mm/sec, the mass loss of ferritic samples increases by 10 %. The effect of reducing sliding speed upon the wear of the samples with the structure of martensite and austenite is found to be not so significant. Проведены испытания нелегированных сталей в различном структурном состоянии в диапазоне скоростей скольжения по абразиву 0,1–86 мм/с. Установлено, что снижение скорости скольжения с десятков до единиц миллиметров в секунду по-разному влияет на износ образцов с различным типом структуры. Наиболее существенно увеличивается износ образцов со структурой феррита. При уменьшении скорости скольжения с 86 до 5 мм/с потеря массы ферритных образцов возрастает на 10 %. Влияние снижения скорости на износ образцов со структурой мартенсита и аустенита не столь значительно.

Влияние мартенсита на кинетику бейнитного превращения в сталях 60С2ХФА и 55С3Г2ХФМБА

The effect of cooling below Ms point (up to 160 °С and 200 °С) on the kinetics of bainite transformation in steels 60Si2CrVА and 55Si3Mn2CrVMoNb at isothermal exposure in the range of 225–350 °С is described. It is shown that, in most cases, the appearance of martensite accelerates the beginning of transformation, but leads to a slowing its completion or early delay due to the stabilization of austeniteОписано влияние подстуживания ниже точки Мн (до 160°С и 200 °С) на кинетику бейнитного превращения в сталях 60С2ХФА и 55С3Г2ХФМБА при изотермической выдержке в диапазоне 225–350 °С. Показано, что в большинстве случаев появление мартенсита ускоряет начало превращения, но приводит к замедлению его окончания или ранней приостановке за счет стабилизации аустенит

The influence of surface irregularities on the mechanical properties of thin-walled wire and arc additively manufactured parts

Wire and Arc Additive Manufacturing (WAAM) is a metal additive manufacturing process commonly used to deposition medium to large, near net-shaped parts. It can efficiently use materials and deposit objects with fewer assembly parts. The main disadvantage of WAAM is the surface quality. This work investigates the geometry shift defect that could be formed due to the wear of the welding contact tip. As a result of the wear, the filler wire deviates from the nominal position, and errors occur in the positioning of individual layers of printed parts. The main objective of this work is to investigate the influence of surface irregularities on the mechanical properties of asdeposited thin-walled WAAM parts. Finite element modeling of static and cyclic tensile and compressive tests showed that the surface waviness formed during layer-by-layer deposition increases the stress level under static loading applied transversely to the deposited layers. Surface waviness also significantly reduces the life of parts under cyclic loading. Replacement of a worn contact tip causes the layers to shift, and the resulting load eccentricity increases the stress level. Uneven stress distribution throughout the cross section means reduced material usage efficiency. During compressive loading, the load eccentricity destabilizes, causing the specimen to deform after exceeding the yield strength in stress concentration zones. The relationship between unmachined and machined walls with equivalent stresses was obtained, allowing the influence of surface waviness on the strength and durability of structures to be considered at the design stage

Comparative study on the effect of (Cr, Mo, V)-alloying on transformation and mechanical behavior of 0.2 wt.% C TRIP-assisted steel

The structure and mechanical properties of two 0.2 wt.% C TRIP-assisted steels (Transformation Induced Plasticity) were compared to evaluate the effect of additional (Cr, Mo, V)-alloying on transformation kinetic and tensile/impact behavior after isothermal bainite transformation (bainitizing) and Q&P (Quenching-and-Partitioning) treatment. The work was performed using SEM, XRD, tensile/impact testing, and computer simulation. It was found that adding 0.55 wt.% Cr, 0.2 wt.% Mo, and 0.11 wt.% V into Mn-Si-Nb steel increased the incubation time in pearlite and bainite temperature ranges by 5.6 and 4.4 times, respectively. More heavily alloyed steel performed an improved combination ???Strength/Ductility/Impact Toughness???: its maximum PSE (Product of Strength and Elongation) value of 24 GPa ?? % referred to bainitizing treatment, whereas the highest KCV20???C values (220???225 J cm???2) corresponded to Q&P treatment. Improved mechanical properties of (Cr, Mo, V)-alloyed steel were attributed to a higher amount of retained austenite and a slower rate of TRIP-effect