Mechanical properties of ausforged 27MnSiVS6 microalloyed steel

Caminaga, Célio; Button, Sérgio Tonini

doi:10.1590/s0370-44672013000300010

Cited by 4 publications

(1 citation statement)

References 26 publications

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“…Keywords: hot forging, porous preforms, contact endurance, low-cycle fatigue, brittle and ductile fracture, interparticle jointing, alloying, microalloying, sodium bicarbonate, calcium carbonate, oxidation, chromium-molybdenum iron powder, thermal treatment (TT), thermomechanical treatment (TMT). механической обработки является аусформинг (ausforming), или низкотемпературная термомеханическая обработка (НТМО), заключающаяся в деформировании стали при температурах метастабильного состояния аустенита ниже порога рекристаллизации [7]. Возможность проявления эффекта НТМО при ГШПЗ до настоящего времени в литературе не рассматривалась (в отличие от ВТМО).…”

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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Development of ultra high strength 27MnSiVS6 micro-alloyed steel by austempering and forced cooling conditions

et al. 2022

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Análise experimental em um cilindro de varetas de uma colhedora de café para diagnóstico de falha

et al. 2020

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Colhedoras de café trabalham com um sistema de vibração para promover a derriça dos grãos. O sistema de vibração geralmente é acoplado na extremidade de um eixo, denominado por cilindro vibrador de varetas. Este cilindro pode apresentar falhas em campo, as quais geralmente ocorrem por fratura na região da solda entre o cilindro e seu flange. Observa-se em campo que, este tipo de falha ocorre em um curto intervalo de tempo, antes de 12 meses de trabalho constante, o que requer diagnóstico de falhas. Este trabalho tem como objetivo principal realizar o diagnóstico de falha em um cilindro vibrador de varetas de uma colhedora de café. Para isso, foi realizado o mapeamento da fratura e foram confeccionados corpos de prova para a realização de ensaios mecânicos destrutivos e não destrutivos (ensaio de tração, análise química dos materiais do cilindro vibrador de varetas e flange, metalografia das juntas soldadas e ensaios de dureza Vickers e Brinell. Os resultados das análises químicas e de dureza Brinell comprovaram que o material do cilindro de varetas se trata de um aço de baixo teor de carbono. Os resultados de dureza Vickers evidenciaram a não homogeneidade do metal depositado. Os resultados obtidos nos ensaios de tração foram próximos a valores encontrados na literatura, exceto para o alongamento. Os resultados metalográficos da junta soldada evidenciaram defeitos, como trinca e porosidade, que podem influenciara fratura. Neste sentido, foi proposto um procedimento de soldagem (EPs) para a melhoria do processo de fabricação da peça analisada. Palavras-chave: Colhedora de café. Ensaio mecânicos. Diagnóstico de falhas. Experimental analysis in a stell cylinder of a coffee harvest for failure diagnosis Abstract Coffee harvesters work with vibration system in order to promote the breaking of the grains peduncle. The vibration system is usually coupled to the end of an axis, called a rod vibrating cylinder. This cylinder can present failures on duty, which usually occurs due to fracture failure in the weld region between the cylinder and its flange. It is observed that this type of failure occurs in a short time, before 12 months of constant work, which requires a failure diagnosis. The main objective of this work is to perform failure diagnosis in the vibrating rod cylinder of a coffee harvester. To this end, a the fracture mapping was performed and samples were made specimens for destructive and non-destructive mechanical tests, such as tensile testing, chemical analysis of the pipe and flange materials, metallography of the welded joints and hardness testing Vickens and Brinell. Through these tests, it was observed problems due to the welding process applied between the rod cylinder and the flange, and to manufacturing defects of the axle (arising from the casting process). As a result, it was observed a probable fatigue failure process leading to a short service life in the cylinder-flange assembly. To solve this problem, a welding procedure (EPs) is proposed to improve the fabrication process of the rod cylinder. Keywords: Coffee harvester. Mechanical tests. Failure diagnosis.

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Mechanical properties of ausforged 27MnSiVS6 microalloyed steel

Cited by 4 publications

References 26 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

Development of ultra high strength 27MnSiVS6 micro-alloyed steel by austempering and forced cooling conditions

Análise experimental em um cilindro de varetas de uma colhedora de café para diagnóstico de falha

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