Effect of calcium on grain boundary embrittlement of structural steel strengthened with carbonitrides

Бродецкий, И. Л.; Kharchevnikov, V. P.; Белов, Б. Ф.; Троцан, А. И.

doi:10.1007/bf01156894

Cited by 5 publications

(2 citation statements)

References 2 publications

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“…Образующиеся при этом дисперсные Caсодержащие оксиды, локализованные на межчастичных границах, не являются фактором разупрочнения порошковой стали [18]. Кроме того, некоторая часть кальция адсорбируется на внутризеренных дефектах в виде сегрегаций, увеличивая долю металлической составляющей связи, что приводит, как и у литых низколегированных сталей, к повышению энергоемкости хрупкого внутризеренного разрушения [19,20]. Введение микродобавок Na или Ca способствует росту контактной долговечности, прочности и ударной вязкости горячедеформированных порошковых сталей эвтектоидного состава в состоянии после цементации и термообработки за счет повышения качества межчастичного сращивания и уменьшения размера зерна аустенита [21,22].…”

Section: Introductionunclassified

Formation of structure and properties of hot-deformed powder steels microalloyed with sodium and calcium during thermal and thermomechanical treatment

Дорофеев¹,

Свиридова²,

Samoilov³

2021

Izv. VUZ. Poroshk. Met.

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One of the main problems limiting further growth in the production of parts by the hot forging of porous performs (HFPP) is that the obtained materials are prone to brittle fracture due to the poor quality of interparticle jointing formed during hot deformation, as well as the presence of impurities in the composition of initial powders. The paper studies the possibility of increasing the mechanical properties and endurance performance of hot-deformed powder steels by doping them with sodium or calcium microadditives and using thermomechanical treatment. Sodium bicarbonate and calcium carbonate were used for microalloying. Carbon was added as pencil graphite powder. The temperature of heating porous preforms before hot forging and the carbon content in steels were varied; the content of microalloying additives was, wt.%: 0.2 for sodium, and 0.3 for calcium. Mechanical properties as well as contact and low-cycle fatigue life were tested on 5 × 10 × 55 mm and 10 × 10 × 55 mm prismatic specimens, as well as ∅ 26 × 6 mm cylindrical specimens. In comparison with carburizing and thermal treatment, thermomechanical treatment improves the impact strength and endurance performance of hot-deformed powder steels with Na or Ca microadditives under the contact and low-cycle fatigue loading, and the hot repressing temperature of porous preforms is reduced without compromising the mechanical properties of powder steels obtained. It may be associated with the formation of a more fine-grained structure and higher microstresses of the crystal lattice. The cooling down of preform surface layers during hot forging process operations creates conditions for ausforming in them.

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Section: Introductionunclassified

Formation of structure and properties of hot-deformed powder steels microalloyed with sodium and calcium during thermal and thermomechanical treatment

Дорофеев¹,

Свиридова²,

Samoilov³

2021

Izv. VUZ. Poroshk. Met.

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“…We look for the preferred positions of impurities at the GB and analyze their effect on atomic arrangement and magnetism. Though the physical mechanisms behind GB embrittlement and strengthening have been studied in detail for some materials [16][17][18][19], the specific interactions between GBs, impurities and vacancies are usually not taken into account. In our approach to segregation, not only the final equilibrium state of the studied system is characterized, but we also explore the way how it was achieved.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Vacancies on Grain Boundary Segregation in Ferromagnetic fcc Ni

et al. 2020

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This work presents a comprehensive and detailed ab initio study of interactions between the tilt Σ5(210) grain boundary (GB), impurities X (X = Al, Si) and vacancies (Va) in ferromagnetic fcc nickel. To obtain reliable results, two methods of structure relaxation were employed: the automatic full relaxation and the finding of the minimum energy with respect to the lattice dimensions perpendicular to the GB plane and positions of atoms. Both methods provide comparable results. The analyses of the following phenomena are provided: the influence of the lattice defects on structural properties of material such as lattice parameters, the volume per atom, interlayer distances and atomic positions; the energies of formation of particular structures with respect to the standard element reference states; the stabilization/destabilization effects of impurities (in substitutional (s) as well as in tetragonal (iT) and octahedral (iO) interstitial positions) and of vacancies in both the bulk material and material with GBs; a possibility of recombination of Si(i)+Va defect to Si(s) one with respect to the Va position; the total energy of formation of GB and Va; the binding energies between the lattice defects and their combinations; impurity segregation energies and the effect of Va on them; magnetic characteristics in the presence of impurities, vacancies and GBs. As there is very little experimental information on the interaction between impurities, vacancies and GBs in fcc nickel, most of the present results are theoretical predictions, which may motivate future experimental work.

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Embrittlement of electrical steel laminations by nitrogen pick-up during heat treatment

Landgraf

Tschiptschin

2010

Engineering Failure Analysis

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Effect of calcium on grain boundary embrittlement of structural steel strengthened with carbonitrides

Cited by 5 publications

References 2 publications

Formation of structure and properties of hot-deformed powder steels microalloyed with sodium and calcium during thermal and thermomechanical treatment

Formation of structure and properties of hot-deformed powder steels microalloyed with sodium and calcium during thermal and thermomechanical treatment

The Effect of Vacancies on Grain Boundary Segregation in Ferromagnetic fcc Ni

Embrittlement of electrical steel laminations by nitrogen pick-up during heat treatment

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