Kriyojenik işlemin AISI 431 paslanmaz çeliğinin mekanik özellikleri üzerine etkilerinin araştırılması
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Tarih
2022
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Düzce Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bu çalışmada, AISI 431 martenzitik paslanmaz çeliğinin mekanik ve mikroyapısal özellikleri üzerine sığ ve derin kriyojenik işlemin etkileri araştırılmıştır.Çelik numuneler öncelikle 980 °C'de 30 dakika bekletildikten sonra yağda soğutulmuş ve ardından 650 °C'de 2 saattemperlenmiştir. Bu işlemin ardından çelik numuneler üzerine -80 °C'de 12 saat (SKİ12T) ve 24 saat (SKİ24T) süre ile sığ kriyojenik işlem, -180 °C'de 6 saat (DKİ6T), 12 saat (DKİ12T), 18 saat (DKİ18T), 24 saat (DKİ24T) ve 36 saat (DKİ36T) süre ile derin kriyojenik işlem uygulanmıştır.Geleneksek sertleştirme ısıl işlemi uygulanmış numuneye kıyasla 200 °C'detemperlenmiş numunenin sertlik, çekme, akma ve aşınma direncinin sırasıyla yaklaşık %3,89, %1,44, %6,95 ve %62 oranlarda arttığı gözlenmiştir. 300 °C'detemperlenmiş numunelerin işlemsiz numuneye göre sertlik, çekme, akma ve aşınma direncinin sırasıyla yaklaşık %3,52, %1,18, %7,03 ve %56 oranlarda arttığı görülmüştür. 200 °C'de temperlenmiş numunelerin genel olarak daha iyi mekanik özellikler sergilediği tespit edilmiştir. Diğer kriyojenik işlem uygulanmış tüm numunelere 200 °C'de 2 saat süre ile temperleme işlemi uygulanmıştır. Yapılan testler sonucunda, farklı bekletme sürelerinde kriyojenik işlem uygulanmış numunelerde işlemsiz numuneye göre sertlik, çekme, akma ve aşınma direncinde artış olduğu ve bu artışların her iki kriyojenik işlem türünde de bekletme sürelerinin artmasıyla doğru orantılı olduğu görülmüştür. İşlemsiz numuneye kıyasla SKİ24T numunenin sertlik, çekme, akma ve aşınma direnci sırasıyla yaklaşık %5,37, %1,59, % 7,11 ve %78 oranlarda artmıştır. İşlemsiz numuneye kıyasla DKİ36T numunenin sertlik, çekme, akma ve aşınma direnci sırasıyla yaklaşık %5,87, %1,66, %8,17 ve %88 oranlarda artmıştır. Çalışma sonucunda her iki kriyojenik işlem türü ve tüm bekletme sürelerinin işlemsiz numuneye kıyasla mekanik özelliklerde artış sağladığı görülmekle beraber derin kriyojenik işlemin daha üstün mekanik özellikler sağladığı tespit edilmiştir.Mikroyapısal incelemelerde, tüm numuneler için kalıntı östenitli bir çıta tipi martenzit yapı oluştuğu görülmüştür. Bununla birlikte kriyojenik işlem uygulanmış numunelerdeki martenzitik çıtalar işlemsiz numuneye kıyasla daha küçüktür. En yüksek mekanik özellikler 36 saat süre ile uygulanan derin kriyojenik işlem ile elde edilmiştir. Çalışmada kriyojenik işlemin AISI 431 martenzitik paslanmaz çeliğin diğer mekanik özelliklerinde (sertlik, çekme ve akma) artış sağlamakla birlikte özellikle aşınma direncinde belirgin bir artış sağladığı görülmüştür. Anahtar Kelimeler: AISI 431 martenzitik paslanmaz çeliği, Derin kriyojenik işlem, Mekanik özellikler, Mikroyapı, Sığ kriyojenik işlem
This study investigated the effects of shallow and deep cryogenic treatment on the mechanical and microstructural properties of AISI 431 martensitic stainless steel. Steel samples were first kept at 980 °C for 30 minutes, then cooled in oil, and then tempered at 650 °C for 2 hours. After this process, shallow cryogenic treatment was applied at -80 °C for 12(SKİ12T) and 24 hours(SKİ24T), and deep cryogenic treatment was applied at -180 °C for 6 (DKİ6T), 12 (DKİ12T), 18 (DKİ24T), 24 (DKİ6T), and 36 (DKİ36T) hours on steel samples. It was observed that the hardness, tensile, yield, and abrasion resistance of the sample tempered at 200 °C increased by approximately 3.89%, 1.44%, 6.95%, and 62%, respectively, compared to the conventional hardening heat-treated sample. It was observed that the hardness, tensile, yield, and abrasion resistance of the samples tempered at 300 °C increased by approximately 3.52%, 1.18%, 7.03%, and 56%, respectively, compared to the untreated sample. It has been found that samples tempered at 200 °C generally exhibit beter mechanical properties. All other cryogenically treated samples were tempered at 200 °C for 2 hours. As a result of the tests, it was observed that the hardness, tensile, yield, and abrasion resistance of the cryogenically treated samples at different holding times increased compared to the untreated sample, and these increases were directly proportional to the increase in the holding times in both cryogenic treatment types. Compared to the untreated sample, the hardness, tensile, yield, and abrasion resistance of the SKİ24T sample increased by approximately 5.37%, 1.59%, 7.11%, and 78%, respectively. Hardness, tensile, yield, and abrasion resistance of the DKİ36T sample increased by approximately 5.87%, 1.66%, 8.17%, and 88%, respectively, compared to the untreated sample. As a result of the study, it has been determined that both cryogenic treatment types and all holding times increase mechanical properties compared to the untreated sample, while deep cryogenic treatment provides superior mechanical properties. In microstructural studies, a lath-type martensite structure with residual austenite was observed for all samples. However, the martensitic laths in the cryogenically treated samples are smaller than in the untreated sample. The highest mechanical properties were obtained by deep cryogenic treatment applied for 36 hours. The study observed that cryogenic treatment increased other mechanical properties (hardness, tensile,and yield) of AISI 431 martensitic stainless steel, but especially a significant increase in wear resistance. Keywords: AISI 431 martensitic stainless steel, Deep cryogenic treatment, Mechanical properties, Microstructure, Shallow cryogenic treatment
This study investigated the effects of shallow and deep cryogenic treatment on the mechanical and microstructural properties of AISI 431 martensitic stainless steel. Steel samples were first kept at 980 °C for 30 minutes, then cooled in oil, and then tempered at 650 °C for 2 hours. After this process, shallow cryogenic treatment was applied at -80 °C for 12(SKİ12T) and 24 hours(SKİ24T), and deep cryogenic treatment was applied at -180 °C for 6 (DKİ6T), 12 (DKİ12T), 18 (DKİ24T), 24 (DKİ6T), and 36 (DKİ36T) hours on steel samples. It was observed that the hardness, tensile, yield, and abrasion resistance of the sample tempered at 200 °C increased by approximately 3.89%, 1.44%, 6.95%, and 62%, respectively, compared to the conventional hardening heat-treated sample. It was observed that the hardness, tensile, yield, and abrasion resistance of the samples tempered at 300 °C increased by approximately 3.52%, 1.18%, 7.03%, and 56%, respectively, compared to the untreated sample. It has been found that samples tempered at 200 °C generally exhibit beter mechanical properties. All other cryogenically treated samples were tempered at 200 °C for 2 hours. As a result of the tests, it was observed that the hardness, tensile, yield, and abrasion resistance of the cryogenically treated samples at different holding times increased compared to the untreated sample, and these increases were directly proportional to the increase in the holding times in both cryogenic treatment types. Compared to the untreated sample, the hardness, tensile, yield, and abrasion resistance of the SKİ24T sample increased by approximately 5.37%, 1.59%, 7.11%, and 78%, respectively. Hardness, tensile, yield, and abrasion resistance of the DKİ36T sample increased by approximately 5.87%, 1.66%, 8.17%, and 88%, respectively, compared to the untreated sample. As a result of the study, it has been determined that both cryogenic treatment types and all holding times increase mechanical properties compared to the untreated sample, while deep cryogenic treatment provides superior mechanical properties. In microstructural studies, a lath-type martensite structure with residual austenite was observed for all samples. However, the martensitic laths in the cryogenically treated samples are smaller than in the untreated sample. The highest mechanical properties were obtained by deep cryogenic treatment applied for 36 hours. The study observed that cryogenic treatment increased other mechanical properties (hardness, tensile,and yield) of AISI 431 martensitic stainless steel, but especially a significant increase in wear resistance. Keywords: AISI 431 martensitic stainless steel, Deep cryogenic treatment, Mechanical properties, Microstructure, Shallow cryogenic treatment
Açıklama
Anahtar Kelimeler
AISI 431 martenzitik paslanmaz çeliği, Derin kriyojenik işlem, Mekanik özellikler, Mikroyapı, Sığ kriyojenik işlem, AISI 431 martensitic stainless steel, Deep cryogenic treatment, Mechanical properties, Microstructure, Shallow cryogenic treatment, Mühendislik Bilimleri, Engineering Sciences
