Sains Malaysiana 54(8)(2025): 2045-2057

http://doi.org/10.17576/jsm-2025-5408-14

 

Microstructural Evolution and Performance of Heat-Treated Ti6Al4V in Laser Powder Bed Fusion

(Evolusi Mikrostruktur dan Prestasi TI6AL4V Haba Terawat dalam Haba Pelakuran Lapisan Serbuk Laser)

 

FARHANA MOHD FOUDZI^1,2,*, MINHALINA AHMAD BUHAIRI^1,2,3, FATHIN ILIANA JAMHARI^1,2, NORHAMIDI MUHAMAD^1,2, INTAN FADHLINA MOHAMED^1,2, ABU BAKAR SULONG^1,2, NASHRAH HANI JAMADON^1,2 & NABILAH AFIQAH MOHD RADZUAN^1,2

 

¹Advanced Manufacturing Research Group, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

²Department of Mechanical and Manufacturing Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

³Doctoral School on Materials Science and Technologies, Óbuda University, Nepszinhaz u. 8, 1081 Budapest, Hungary

 

Diserahkan: 21 Februari 2025/Diterima: 16 Jun 2025

 

Abstract

Ti6Al4V parts produced via laser powder bed fusion (LPBF) frequently exhibit high residual stress, where heat treatment has been utilized to relieve this stress. This study aims to investigate the effect of annealing heat treatment on the overall performance of Ti6Al4V fabricated using LPBF. Printed Ti6Al4V samples were heat treated at 935 °C for 8 hours with a heating rate of 5 °C/min and a cooling rate of 0.60 °C/min. The overall performance such as physical properties, mechanical properties and microstructure observation between as-built and heat-treated samples were compared. The heat treatment was able to produce high-density parts, with surfaces as smooth as 5.70 μm, reaching up to 99.28% density. The annealing process significantly improved the ductility of Ti6Al4V parts by up to 231%, while decreasing the tensile strength by 28% and the hardness by 13%. The microstructure of as-built samples shifts from acicular α' martensite to α+β phases after annealing at 935 °C for 8 hours, supporting the changes in mechanical performance. This preliminary study concludes that the heat treatment used following LPBF printing can create Ti6Al4V samples with acceptable physical, mechanical, and microstructure properties.

Keywords: Hardness; heat treatment; laser powder bed fusion; microstructure; Ti6Al4V

 

Abstrak

Produk Ti6Al4V yang dihasilkan melalui kaedah pelakuranlapisan serbuk laser (LPBF) kebiasaannya menjana tegasan baki yang tinggi dengan rawatan haba digunakan untuk mengurangkan tegasan ini. Penyelidikan ini bertujuan untuk mengkaji kesan rawatan haba penyepuhlindapan ke atas prestasi keseluruhan produk Ti6Al4V yang dihasilkan menggunakan LPBF. Sampel Ti6Al4V telah dirawat haba pada 935 °C selama 8 jam menggunakan kadar pemanasan sebanyak 5 °C/min dan kadar penyejukan sebanyak 0.60 °C/min. Prestasi keseluruhan merangkumi sifat fizikal, sifat mekanikal dan analisis mikrostruktur antara sampel sebelum dan selepas dirawat haba telah dibandingkan. Rawatan haba yang telah dijalankan mampu menghasilkan sampel berketumpatansetinggi 99.28% dengan permukaan selicin5.70 μm. Proses penyepuhlindapan ini juga berjaya meningkatkan kemuluran sampel Ti6Al4V sebanyak 231%, namun proses ini mengurangkan kekuatan tegangan sebanyak 28% dan kekerasan sebanyak 13%. Mikrostruktur sampel yang telah dicetak 3D berubah daripada jejarum α' martensit kepada fasa campuran α+β selepas dirawat haba pada 935 °C selama 8 jam dan ini menyokong perubahan sifat mekanikal. Kajian awal ini menyimpulkan bahawa rawatan haba yang digunakan selepas percetakan LPBF mampu menghasilkan sampel Ti6Al4V dengan sifat fizikal, mekanikal dan mikrostruktur yang boleh diterima.

Kata kunci: Kekerasan; mikrostruktur; pelakuran lapisan serbuk laser; rawatan haba; Ti6Al4V

 

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*Pengarang untuk surat-menyurat; email: farhana.foudzi@ukm.edu.my