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  • Kapalı Erişim
    Yayın
    Drilling response of additively manufactured and cast AISI H13 hot-work tool steel by thermal and mechanical processes
    (Springer Science and Business Media Deutschland GmbH, 2026) Günen, Ali; Heidarzadeh, Akbar; Ceritbinmez, Ferhat; Kanca, E.; Li, W.; Çam, Gürel
    Precise micro-hole fabrication in additively manufactured parts has remained a big challenge in such high-accuracy applications as aerospace, medical devices, and microelectronics. Micro-drilling is one of the critical post-machining techniques that can overcome such limitations. In view of their different microstructural and mechanical properties, this paper investigates the micro-drilling performance of AISI H13 tool steel fabricated by selective laser melting (SLM) and casting. The comparison was performed based on drilling 3 mm micro-holes by mechanical and thermal drilling. The performance of cast H13 steel with its homogeneous crystalline structure, lower hardness, and residual stress was better than that of SLM-H13 both in conventional and laser drilling. It has presented less deformation and higher surface quality with less cutting waste. In contrast, heterogeneous microstructural SLM-H13 steel showed higher dislocation density due to non-uniform heat distribution, more molten material, and higher defect incidences after laser drilling. In orbital drilling with WC tools, the harder SLM-H13 steel also offered high accuracy, while conventional drilling was sufficient in the cast H13. Laser drilling presented larger kerf angles and heat-affected zones, while the mechanical drilling presented superior dimensional accuracy.
  • Küçük Resim
    Yayın
    The role of test environment on the tribological behavior of Co-free FeNiMnCrTiAl high entropy alloy
    (Elsevier Ltd, 2025) Günen, Ali; Kanca, Yusuf; Şatır, Ender Yetkin; Serindağ, Hüseyin Tarık; Heidarzadeh, Akbar; Çam, Gürel
    The wear behavior of high entropy alloys is of great importance due to their use in harsh operating conditions in applications such as marine, chemical processing and energy production. For this reason, this study aims to investigate the tribological performance of Co-free FeNiMnCrTiAl high entropy alloy in dry sliding, seawater and H2SO4 (0.5 M and 0.005 M) environments. Wear tests according to ASTM G133 standard were performed against Al2O3 ball at 2.5 N, 5 N and 10 N loads, 2 Hz reciprocating frequency, 5 mm stroke and 20 mm/s sliding speed for 100 m sliding distance. The microstructure of the high entropy alloy produced by casting, homogenization and hot rolling consists of simple face-centered cubic (FCC) and Cr2Al phases. Key findings demonstrate that the alloy exhibits significantly superior wear resistance in corrosive environments compared to dry sliding, with the wear resistance ranking as follows: 0.5 M H₂SO₄ > 0.5 H₂SO₄ 10−3 M > seawater > dry sliding. The enhanced performance in liquid media is attributed to tribo-chemical film formation, cooling, and effective debris removal. Distinct wear mechanisms were identified across conditions: abrasive wear dominated under low-load dry sliding, transitioning to oxidative and delamination mechanisms at higher loads. In seawater, mixed-mode wear involving delamination and tribo-oxide layer interaction was observed. Acidic environments revealed load-dependent behavior, with adhesive and plastic deformation at 2.5 N, micro-scratching at 5 N, and severe abrasive-oxidative wear at 10 N. Interestingly, surface degradation was more pronounced in the 0.005 M H₂SO₄ solution due to unstable passive film formation, despite its lower acidity. The results of this study demonstrated that the Co-free FeNiMnCrTiAl HEA exhibits significantly superior wear resistance compared to conventional single-phase FCC HEAs, highlighting its potential as a promising candidate for abrasive and corrosive environments.