Effect of initial grain size on microstructure and toughness of intercritical heat-affected zone of a low carbon steel

Eroğlu, Mehmet S.; Aksoy, M.

doi:10.1016/s0921-5093(00)00801-7

Cited by 43 publications

(23 citation statements)

References 5 publications

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“…Increment of hardness properties in samples processed by 0.4 mm spot size was contributed to by grain refinement along with martensite phase presence, which is in agreement with the XRD findings and previous work [16]. The pulse energy and residence time combination determines the surface heating rate and quench rate of undercooled austenite.…”

Section: Discussionsupporting

confidence: 90%

An investigation of phase transformation and crystallinity in laser surface modified H13 steel

2012

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This paper presents a laser surface modification process of AISI H13 tool steel using 0.09, 0.2 and 0.4 mm size of laser spot with an aim to increase hardness properties. A Rofin DC-015 diffusion-cooled CO 2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). X-ray diffraction analysis (XRD) was conducted to measure crystallinity of the laser-modified surface. X-ray diffraction patterns of the samples were recorded using a Bruker D8 XRD system with CuK α (λ = 1.5405 Å) radiation. The diffraction patterns were recorded in the 2θ range of 20 to 80°. The hardness properties were tested at 981 mN force. The lasermodified surface exhibited reduced crystallinity compared to the un-processed samples. The presence of martensitic phase was detected in the samples processed using 0.4 mm spot size. Though there was reduced crystallinity, a high hardness was measured in the laser-modified surface. Hardness was increased more than 2.5 times compared to the as-received samples. These findings reveal the phase source of the hardening mechanism and grain composition in the lasermodified surface.

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Section: Discussionsupporting

confidence: 90%

An investigation of phase transformation and crystallinity in laser surface modified H13 steel

2012

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“…Large austenite grain sizes are of particular concern during welding where the HAZ experiences rapid thermal cycles with high peak temperatures which give rise to austenite grain growth, especially in the region adjacent to the fusion zone. Martensite formation in this coarse grain region may lower the weld toughness and increase the risk of hydrogen cracking [3][4][5][6][7][8]. It also has an impact on the vulnerability to cold cracking and reheat cracking of welds.…”

Section: Introductionmentioning

confidence: 99%

In situ measurement and modelling of austenite grain growth in a Ti/Nb microalloyed steel

et al. 2012

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In situ measurement and modelling of austenite grain growth in a Ti/Nb microalloyed steel Maalekian, M.; Radis, R.; Militzer, M.; Moreau, A.; Poole, W. J.In situ measurement and modelling of austenite grain growth in a Ti/Nb microalloyed steel Abstract Using a novel laser ultrasonics technique in situ measurements of austenite grain growth were conducted during continuous heating (10°Cs À1 ) and subsequent isothermal holding at various temperatures in the range 950-1250°C in a microalloyed linepipe steel. Based on the experimental results, a grain growth model was developed, which includes the pinning effect of precipitates present in the steel. Analyzing the grain growth behaviour and using the advanced thermo-kinetic software MatCalc, an approach was developed to estimate the initial distribution of precipitates in the as-received material and their dissolution kinetics. The evolution of the volume fractions and mean particle sizes of NbC and TiN leads to a time-dependent pinning pressure that is coupled with the proposed grain growth model to successfully describe the observed kinetics of austenite grain growth. The predictive capabilities of the model are illustrated by its application to independent grain growth data for rapid heat treatment cycles that are typical of the weld heat affected zone.

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“…Neste caso a energia de soldagem foi muito mais elevada e não houve refinamento pelo passe subseqüente, (ver Tabela 5), proporcionando uma taxa de resfriamento muito baixa e, consequentemente uma redução na dureza, aumentando a possibilidade de formação de Ferrita de Widmasttaten na ZTA, e queda significativa na resistência mecânica da junta, o que é preocupante para os aços ARBL, cujo principal objetivo é possuir alta resistência mecânica associada à boa tenacidade [17].…”

Section: Perfil De Microdurezaunclassified

Estudo do comportamento do aço API 5L X80 quando submetido à soldagem por processo automatizado

et al. 2012

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Resumo IntroduçãoAtualmente no Brasil a demanda energética apresenta uma projeção crescente o que faz com que se intensifiquem os investimentos no setor de petróleo e gás, este fato justifica a procura por técnicas de menor custo para montagem de dutos. Na linha de redução de custos uma iniciativa é a utilização de tubos com menor espessura de parede e processos de soldagem com maior produtividade.A característica citada para os tubos conduz à utilização de aços de alta resistência e baixa liga que possuem alta resistência a esforços, boa tenacidade e boa soldabilidade, função de uma combinação de baixo teor de Carbono e processos termomecânicos de fabricação.Uma classificação de aços indicados para o transporte de petróleo e gás é especificada na API 5L [1], sendo o aço em estudo classificado como API 5L X80, vários trabalhos reportam a boa soldabilidade deste aço [2,3,4,5].Durante a soldagem destes aços, se a taxa de resfriamento é alta, a austenita enriquecida de carbono transforma-se parcialmente em martensita e a austenita restante fica retida à temperatura ambiente formando o microconstituinte AM, que pode resultar em zonas de fragilização localizada que degradam a tenacidade na região de grãos grosseiros da zona termicamente afetada -ZTA GG [6]; logo, para que ocorra boa tenacidade na zona termicamente afetada -ZTA é importante observar a quantidade, tipo e distribuição do constituinte A-M ai presente [7]; Davis e King [8] enfatizam que a presença do constituinte A-M não é necessariamente nociva, depende da sua fração volumétrica, morfologia e dureza, fato também observado por

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Effect of initial grain size on microstructure and toughness of intercritical heat-affected zone of a low carbon steel

Cited by 43 publications

References 5 publications

An investigation of phase transformation and crystallinity in laser surface modified H13 steel

An investigation of phase transformation and crystallinity in laser surface modified H13 steel

In situ measurement and modelling of austenite grain growth in a Ti/Nb microalloyed steel

Estudo do comportamento do aço API 5L X80 quando submetido à soldagem por processo automatizado

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