Effect of post fabrication aging treatment on the microstructure, crystallographic texture and elevated temperature mechanical properties of IN718 alloy fabricated by selective laser melting

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2022

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Elsevier Science Sa

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Metallurgical and Materials Engineering
(2004)
The main fields of operation for Metallurgical and Materials Engineering are production of engineering materials, defining and improving their features, as well as developing new materials to meet the expectations at every aspect of life and the users from these aspects. Founded in 2004 and graduated its 10th-semester alumni in 2018, our Department also obtained MÜDEK accreditation in the latter year. Offering the opportunity to hold an internationally valid diploma through the accreditation in question, our Department has highly qualified and experienced Academic Staff. Many of the courses offered at our Department are supported with various practice sessions, and internship studies in summer. This way, we help our students become better-equipped engineers for their future professional lives. With the Cooperative Education curriculum that entered into effect in 2019, students may volunteer to work at contracted companies for a period of six months with no extensions to their period of study.
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Department of Metallurgical and Materials Engineering
Metalurji ve Malzeme Mühendisliğinin alanı çok geniştir ve temel olarak metaller, seramikler, polimerler ve bu üç malzemenin birlikte oluşturdukları kompozit malzemelerin üretimlerini, şekillendirilmelerini, işlemlerini, karakterizasyonlarını ve kullanımlarındaki davranışlarını kapsar. Yüksek Lisans programımızda amacımız, öğrencilerimizin bu konulardan bir veya birkaçında kapsamlı ve derin bir kuramsal ve uygulamalı bilgi birikimine sahip olmaları ve bilgiye ulaşma, ulaşılan bilgileri değerlendirme, deney tasarlama, deney sonuçlarını analiz etme ve raporlama yeteneklerini kazanmalarıdır. Web sayfamızda yer alan bilgilerden de görülebileceği gibi modern cihaz ve ekipmanla donatılmış güçlü laboratuvar altyapımız çok farklı konularda araştırma yapılmasını olanaklı kılmaktadır. Yüksek Lisans müfredatımızda Malzemelerin İleri Termodinamiği, Malzeme Mühendisliğinde Matematiksel Yöntemler ve Malzeme-Süreç Seçimi ve Tasarım Problemleri isimli üç zorunlu ders yer almaktadır. Tezli Yüksek Lisans programımız bu zorunlu derslerin yanında zorunlu olan Seminer, Yüksek Lisans Tezi ve dört teknik seçmeli dersten, Tezsiz Yüksek Lisans programımız ise zorunlu olan Bitirme Projesi ve 7 teknik seçmeli dersten oluşmaktadır. Teknik seçmeli dersler tez danışmanının onayı dâhilinde çok sayıdaki teknik seçmeli ders arasından seçilmektedir. Programımıza Metalurji ve Malzeme Mühendisliği mezunlarının yanısıra diğer Mühendislik Bölümleri ile Fizik, Kimya vb. bölümlerin mezunları da kabul edilebilmektedir. Bu bölümlerden mezun olan adayların, her birinin akademik ve profesyonel birikimlerine göre belirlenecek bir bilimsel hazırlık programını tamamlamaları gerekmektedir.

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Abstract

The effect of building direction and post fabrication aging treatment on the microstructure, crystallographic texture and high temperature mechanical properties of Inconel 718 (IN718) alloy fabricated by selective laser melting (SLM) method was investigated. After aging, arc-shaped structures seen in as-fabricated samples dis-appeared and converted into a mixture of columnar and equiaxed grains. Nano-sized gamma '' and/or gamma' precipitates were formed upon aging; however, MC type carbides and Laves phase encountered in as-fabricated samples were not dissolved completely after aging. Moreover, aging did not alter the texture ((001)//building direction (BD)) of as-fabricated samples. Mechanical properties of the alloys under tension were influenced by the build direction, aging time and test temperature. As-fabricated samples produced in vertical direction exhibited higher room temperature strengths with lower ductility due to orientation of overlapped prior melt pools. Room temperature tensile test results revealed that peak aging caused a significant improvement in ultimate tensile strength (UTS), from 1066.5 MPa and 998.4 MPa to 1408.5 MPa and 1330.4 MPa whereas elongation values decreased from 27.5% and 32.2% to 19.6% and 23.7% in vertically and horizontally built samples, respectively. Peak-aged samples (aged at 700 degrees C for 8 h) tested at 600 degrees C displayed serrated regions in their stress-strain curves due to dynamic strain aging (DSA). Although strength values of the samples displayed an expected decrease by temperature, ductility of the samples reduced to minimum at temperatures around 700-800 degrees C, which was attributed to intermediate temperature embrittlement.

Description

Dericioglu, Arcan/0000-0003-3797-117X; Davut, Kemal/0000-0002-9860-881X; Ozer, Seren/0000-0002-2001-0893

Keywords

Additive manufacturing, Selective laser melting, Inconel 718 alloy, Mechanical properties, Dynamic strain aging, Texture

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15

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306

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https://doi.org/10.1016/j.jmatprotec.2022.117622
 https://hdl.handle.net/20.500.14411/1762

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