PSI - Issue 61

ScienceDirect Available online at www.sciencedirect.com ScienceDirect Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2023) 000 – 000 Available online at www.sciencedirect.com Procedia Structural Integrity 61 (2024) 47–52 Structural Integrity Procedia 00 (2023) 000 – 000

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2452-3216 © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of IWPDF 2023 Chairman 10.1016/j.prostr.2024.06.008 2452-3216 © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of IWPDF 2023 2452-3216 © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of IWPDF 2023 © 2024 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of IWPDF 2023 Chairman Abstract Hot dip aluminizing (HDA) is a surface treatment process in which a metal substrate is coated with a layer of aluminum to enhance its corrosion ad oxidation resistance. However, crack formation can occur during the HDA process possibly due to presence of thermal stresses within the coatings arising from mismatch in thermal expansion coefficients of the aluminide layers and the substrate, brittle nature of the aluminide phases and process parameters. Therefore, optimization of the HDA process parameters such as temperature, dipping time and cooling rate from the dipping temperature might help reducing the possibility of crack formation. Additionally, subsequent diffusion annealing might have an effect on crack formation and overall integrity of the aluminized coating. In this study, an AISI 4140 low alloyed steel was subjected to the HDA process in an Al-11wt.% Si bath at 750  C for 9 minutes and subsequent annealing was performed at 750  C, 800  C and 850  C. Examination of the diffusion annealed samples indicated that there were some cracks within the coatings of the samples, which were annealed at 750  C and 800  C, while there was no cracking on the surface of sample annealed at 850  C. The results were comparatively evaluated by considering the process parameters and the characteristics of the aluminide layers, and was attributed to the formation of ductile and brittle aluminide phases depending on the applied annealing temperature. 1. Introduction Hot-dip aluminizing coatings make different types of metals resistant to both corrosion and high temperature oxidation. In many environments, aluminum protects steel from corrosion as galvanizing. However, zinc coatings are not stable above 200  C. Therefore, aluminizing coatings could be more preferable for high temperatures up to 1150°C (Dey et al. 2023). Two types of hot-dip aluminizing are commercially significant. Type 1 uses aluminum-silicon alloy (5 to 11 % Si) and type 2 uses pure aluminum for the coating. Generally, type 1 is used for high temperature applications, type 2 is used for corrosion applications according to ASTM A463/463M. Because Si acts as a barrier Abstract Hot dip aluminizing (HDA) is a surface treatment process in which a metal substrate is coated with a layer of aluminum to enhance its corrosion ad oxidation resistance. However, crack formation can occur during the HDA process possibly due to presence of thermal stresses within the coatings arising from mismatch in thermal expansion coefficients of the aluminide layers and the substrate, brittle nature of the aluminide phases and process parameters. Therefore, optimization of the HDA process parameters such as temperature, dipping time and cooling rate from the dipping temperature might help reducing the possibility of crack formation. Additionally, subsequent diffusion annealing might have an effect on crack formation and overall integrity of the aluminized coating. In this study, an AISI 4140 low alloyed steel was subjected to the HDA process in an Al-11wt.% Si bath at 750  C for 9 minutes and subsequent annealing was performed at 750  C, 800  C and 850  C. Examination of the diffusion annealed samples indicated that there were some cracks within the coatings of the samples, which were annealed at 750  C and 800  C, while there was no cracking on the surface of sample annealed at 850  C. The results were comparatively evaluated by considering the process parameters and the characteristics of the aluminide layers, and was attributed to the formation of ductile and brittle aluminide phases depending on the applied annealing temperature. Keywords: Hot-dip aluminizing, Flow forming, Microstructure 1. Introduction Hot-dip aluminizing coatings make different types of metals resistant to both corrosion and high temperature oxidation. In many environments, aluminum protects steel from corrosion as galvanizing. However, zinc coatings are not stable above 200  C. Therefore, aluminizing coatings could be more preferable for high temperatures up to 1150°C (Dey et al. 2023). Two types of hot-dip aluminizing are commercially significant. Type 1 uses aluminum-silicon alloy (5 to 11 % Si) and type 2 uses pure aluminum for the coating. Generally, type 1 is used for high temperature applications, type 2 is used for corrosion applications according to ASTM A463/463M. Because Si acts as a barrier * Corresponding author. Tel.: +90 5384182551 E-mail address: aptullah.karakas@repkon.com.tr 3rd International Workshop on Plasticity, Damage and Fracture of Engineering Materials (IWPDF 2023) Crack Formation after Diffusion Annealing of Hot-Dip Aluminized AISI 4140 Steel Aptullah Karakaş 1,2 and Murat Baydoğan 2 3rd International Workshop on Plasticity, Damage and Fracture of Engineering Materials (IWPDF 2023) Crack Formation after Diffusion Annealing of Hot-Dip Aluminized AISI 4140 Steel Aptullah Karakaş 1,2 and Murat Baydoğan 2 1 Repkon Machine and Tool Industry, Istanbul 34980, Türkiye 2 Department of Metallurgical and Materials Engineering, Istanbul Technical University, Istanbul 34469, Türkiye 1 Repkon Machine and Tool Industry, Istanbul 34980, Türkiye 2 Department of Metallurgical and Materials Engineering, Istanbul Technical University, Istanbul 34469, Türkiye Keywords: Hot-dip aluminizing, Flow forming, Microstructure * Corresponding author. Tel.: +90 5384182551 E-mail address: aptullah.karakas@repkon.com.tr