Crack propagation and fracture toughness of Ti6Al4V alloy produced by selective laser melting

Cain, Victoria; Thijs, Lore; Humbeeck, Jan Van; Hooreweder, Brecht Van; Knutsen, R.D.

doi:10.1016/j.addma.2014.12.006

Cited by 213 publications

(174 citation statements)

References 9 publications

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“…Согласно результатам испытаний на растяже-ние можно сделать вывод, что в большинстве слу-чаев вертикальные образцы имеют прочностные свойства ниже, чем горизонтальные, что под-тверждается исследованиями в работах [2,15,17,[23][24]. Значения относительного удлинения об-разцов демонстрируют обратную зависимость: ве-личина δ больше у вертикальных образцов.…”

Section: результаты исследований и их обсуждениеunclassified

Anisotropy of Mechanical Properties of Products Manufactured Using Selective Laser Melting of Powdered Materials

Popovich¹,

Sufiiarov²,

Борисов³

et al. 2016

Izv. VUZ. Poroshk. Met.

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Рассмотрены причины возникновения анизотропии свойств в изделиях, изготавливаемых по технологии селективного лазерного плавления металлических порошковых материалов. Представлены результаты оценки механических свойств образцов из сплавов основе титана Ti-6Al-4V, ВТ6 и жаропрочного никелевого сплава Inconel 718 в различных направ-лениях. Исследована микроструктура компактных образцов, полученных селективным лазерным плавлением. Приведе-на зависимость их механических свойств от ориентации заготовок относительно рабочей платформы установки. Анализ микрошлифов из сплава Ti-6Al-4V показал, что у образца прямоугольной формы направление зеренной структуры со-ответствует направлению выращивания, тогда как при изготовлении тонких элементов сетчатой конструкции за счет их меньшего сечения протекают иные тепловые процессы, что сказывается на условиях кристаллизации и формирующейся микроструктуре: в зависимости от угла наклона элемента сетчатой конструкции изменяются направление и форма зерен. Anisotropy of mechanical properties of products manufactured using selective laser melting of powdered materialsThe paper examines factors leading to anisotropy of properties in products manufactured using lasercusing, a technology consisting in selective laser melting of metal powdered materials. The results obtained when evaluating mechanical properties of specimens made of titanium alloys Ti-6Al-4V, VT6 and heat-resistant nickel alloy Inconel 718 in different directions are presented. The study covers the microstructure of compact specimens obtained using selective laser melting, and describes dependence of their mechanical properties on workpiece orientation with relation to the unit working platform. The study of Ti-6Al-4V microsections showed that the direction of the rectangular specimen grain structure matched the growth direction, whereas thin elements with a lattice structure were made with other thermal processes due to their smaller cross section. This affected crystallization conditions and microstructure being formed: grain directions and shapes changed depending on the lattice structure element inclination.Keywords: additive manufacturing, selective laser melting, powder metallurgy, titanium alloys, nickel alloys, layer-by-layer manufacturing, anisotropy, mechanical properties. ВведениеТехнология селективного лазерного плавления (СЛП) уже сейчас активно применяется для из-готовления металлических изделий, что связано с возможностью производства заготовок, макси-мально близких по своей конфигурации к конеч-ному изделию, напрямую из компьютерной мо-дели, без использования оснастки. Это позволяет экономить материалы и затраты на последующую обработку, а также обеспечивает свободу выбо-ра формы изделий, которая может существенно повысить эксплуатационные характеристики де-талей [1]. Последнее особенно актуально в таких областях, как авиация и медицина. В авиации, где титановые и никелевые сплавы получили широ-кое распространение, предъявляются особенные требования к массе изделий. Применение адди-тивных технологий позволя...

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Section: результаты исследований и их обсуждениеunclassified

Anisotropy of Mechanical Properties of Products Manufactured Using Selective Laser Melting of Powdered Materials

Popovich¹,

Sufiiarov²,

Борисов³

et al. 2016

Izv. VUZ. Poroshk. Met.

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“…The fast cooling does not allow for a full transition to the α phase due to no time for the V atoms to diffuse out of the β structure (Bandyopadhyay et al, 2009). This results in a martensitic type structure with fine α′ plates (Cain et al, 2014). Then as the alloy cooled rapidly the acicular α grains developed.…”

Section: Microstructurementioning

confidence: 99%

“…The grain structure consists of homogeneous acicular grains that are quasi-directional in certain areas. This is due to epitaxial growth of grains, while the part is being built layer-by-layer (Cain et al, 2014). The needle-like grains are acicular α′ (HCP) grains (Hosford, 2010).…”

Section: Microstructurementioning

confidence: 99%

“…The areas where the acicular grains are oriented in the same direction are where β (BCC) grains existed (Bose et al, 1999). When the metal first begins to solidify, it forms the β phase, which then begins to transform to the α phase upon further cooling (Cain et al, 2014). The fast cooling does not allow for a full transition to the α phase due to no time for the V atoms to diffuse out of the β structure (Bandyopadhyay et al, 2009).…”

Section: Microstructurementioning

confidence: 99%

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Laser Engineering Net Shaping of Microporous Ti6Al4V Filters

Gualtieri

Bandyopadhyay

2016

Front. Mech. Eng.

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In many applications, porous metal structures are necessary for proper and optimal function. Yet, these structures can be difficult to build. It is especially difficult if the pore size desired is very fine or on the microscale. For this reason, additive manufacturing processes have been looked at to build these structures. In this study, Laser Engineering Net Shaping (LENS™) processing was experimented with processing interconnected microporous structures. Using Ti6Al4V and only changing processing parameters, porous structures were created having porosity ranging from 21.5 to 15.4%. The microstructure proved to be that of traditional laser processed Ti6Al4V parts. Compression test of these samples showed that the ultimate compressive strength varied from 645 to 556 MPa. Overall, LENS™ proved to be a viable method to make unique interconnected microporous structures that could be easily added to any build without having to change the design.

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“…Then, in order to study the influence of heat treatment on the ductility performance of the SLMfabricated TC4 alloy, the heat treatment steps of our experiment were defined based on the phase diagram of TC4 and relevant investigations [22,23]. Vacuum heat treatment was performed using an N41/H Muffle furnace from Nabertherm company, Lilienthal, Germany.…”

Section: Testing Methodsmentioning

confidence: 99%

Research on Selective Laser Melting of Ti6Al4V: Surface Morphologies, Optimized Processing Zone, and Ductility Improvement Mechanism

Wang

Dou

Yang

2018

Metals

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Abstract:The quality and mechanical properties of titanium alloy fabricated using selective laser melting (SLM) are critical to the adoption of the process which has long been impeded by the lack of uniformity in SLM-fabrication parameter optimization. In order to address this problem, laser power and scanning speed were combined into linear energy density as an independent variable, while surface morphology was defined as a metric. Based on full-factor experiments, the surface quality of SLM-fabricated titanium alloy was classified into five zones: severe over-melting zone, high-energy density nodulizing zone, smooth forming zone, low-energy density nodulizing zone, and sintering zone. The mechanism resulting in the creation of each zone was analyzed. Parameter uniformity was achieved by establishing a parameter window for each zone, and it also revealed that under smooth forming conditions, the relationship of linear energy density to the quality of the formed surface is not linear. It was also found that fabrication efficiency could be improved in the condition of the formation of a smooth surface by increasing laser power and scanning speed. In addition, maximum elongation of the SLM-fabricated titanium alloy increased when the densified parts were processed using an appropriate heat treatment, from a low value of 5.79% to 10.28%. The mechanisms of change in ductility of the alloy were thoroughly analyzed from the perspectives of surface microstructure and fracture morphology. Results indicate that after heat treatment, the microcosmic structure of the alloy was converted from acicular martensite α' phase to a layered α+β double-phase structure, the fracture type also changed from quasi-cleavage to ductile fracture.

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Crack propagation and fracture toughness of Ti6Al4V alloy produced by selective laser melting

Cited by 213 publications

References 9 publications

Anisotropy of Mechanical Properties of Products Manufactured Using Selective Laser Melting of Powdered Materials

Anisotropy of Mechanical Properties of Products Manufactured Using Selective Laser Melting of Powdered Materials

Laser Engineering Net Shaping of Microporous Ti6Al4V Filters

Research on Selective Laser Melting of Ti6Al4V: Surface Morphologies, Optimized Processing Zone, and Ductility Improvement Mechanism

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