Publication: Bor ilaveli HCX takım çeliğinin mikroyapısal ve mekanik özelliklerinin iyileştirilmesi
Abstract
Bu çalışmada, HCx® takım çeliğine FeB ilavesi sayesinde mekanik özelliklerin ve mikroyapının geliştirilmesi ele alınmıştır. Toz karışımları hazırlanırken, ağırlıkça %0,5 bağlayıcı kullanılmıştır. FeB katkısız, ağırlıkça %0,5 ve 1 FeB içeren üç tip toz karışımı elde edilmiştir. Çalışmamızda kullanılan tozlar tartıldıktan sonra, karıştırılıp, peletlenmiştir. Ham numuneler, 1150 ve 1200 °C sıcaklıklarında, 60 dk boyunca, hidrojen gazı atmosferinde sinterlenmiştir. Numunelerin sinterlenmiş yoğunlukları Arşimet prensibi ile çalışan bir düzenek yardımıyla belirlenmiştir. Metalografik olarak hazırlanan numunelerin, mikroyapı incelemeleri ve Rockwell B sertliği ölçümleri yapılmıştır. Numune yüzeyleri, krom çeliğinden imal edilmiş bilyeler yardımıyla; 30 N kuvvet altında, 0,25 m/ s hız ve 1000 m yol boyunca aşındırılmıştır. Aşınma cihazının yazılımı sayesinde bir sürtünme katsayısı - yol grafiği elde edilmiştir. Numunelerin ağırlıkları aşınma testi öncesi ve sonrası tartılmış, böylelikle % ağırlık kaybı ve aşınma oranı verileri elde edilmiştir. Testler ve mikroyapı incelemeleri sonrası elde edilen veriler göz önüne alındığında; 1200 °C sıcaklıkta sinterlenmiş ve ağırlıkça %1 FeB içeren numune en başarılı sonuçları sunmuştur. Bu numune ve 1150 °C sıcaklıkta sinterlenmiş, FeB katkısız numunenin aşınma yüzeyleri SEM yardımıyla görüntülenmiştir. Tüm bulgular birbirleri ile ilişkilendirilerek, FeB katkısının HCx® takım çeliğinin mekanik ve mikroyapı özelliklerine etkisi anlaşılmaya çalışılmıştır.
In this study, the enhancement of mechanical properties and microstructure by adding FeB to HCx® tool steel is discussed. While preparing powder mixtures, 0.5% by weight binder was used. Three types of powder mixtures; which without FeB addition, containing 0.5% and 1 FeB by weight were obtained. After weighing the powders used in our study, they were mixed and pelleted. The green samples were sintered at 1150 °C and 1200 °C for 60 min in an atmosphere of hydrogen gas. The sintered densities of the samples were determined by a mechanism working with Archimedes principle. Microstructure observations and Rockwell B hardness measurements of the samples which were prepared as metallographic were conducted. Sample surfaces were worn under 30 N force, on 0,25 m/ s velocity and through 1000 m distance by chromium steel balls. A friction coefficient - distance graph were provided by the aid of wear device. The weights of the samples were weighed before and after the wear test, so that the % weight loss and wear rate data were obtained. Considering the data obtained after the tests and microstructure investigations; the sample sintered at 1200 °C and containing 1% by weight of FeB showed the best results. The wear surfaces of this sample and the sintered sample without FeB addition at 1150 °C were visualized by the aid of SEM. All findings were correlated with each other and the effect of FeB addition on the mechanical and microstructural properties of HCx® tool steel was tried to be understood.
In this study, the enhancement of mechanical properties and microstructure by adding FeB to HCx® tool steel is discussed. While preparing powder mixtures, 0.5% by weight binder was used. Three types of powder mixtures; which without FeB addition, containing 0.5% and 1 FeB by weight were obtained. After weighing the powders used in our study, they were mixed and pelleted. The green samples were sintered at 1150 °C and 1200 °C for 60 min in an atmosphere of hydrogen gas. The sintered densities of the samples were determined by a mechanism working with Archimedes principle. Microstructure observations and Rockwell B hardness measurements of the samples which were prepared as metallographic were conducted. Sample surfaces were worn under 30 N force, on 0,25 m/ s velocity and through 1000 m distance by chromium steel balls. A friction coefficient - distance graph were provided by the aid of wear device. The weights of the samples were weighed before and after the wear test, so that the % weight loss and wear rate data were obtained. Considering the data obtained after the tests and microstructure investigations; the sample sintered at 1200 °C and containing 1% by weight of FeB showed the best results. The wear surfaces of this sample and the sintered sample without FeB addition at 1150 °C were visualized by the aid of SEM. All findings were correlated with each other and the effect of FeB addition on the mechanical and microstructural properties of HCx® tool steel was tried to be understood.