Mustafa ULUTAN, M.mustafa YILDIRIM, Soner BUYTOZ

TIG Yöntemiyle Yüzeyi Sertleştirilen AISI 4140 Çeliğinin Mikroyapı İncelemesi

Bu çalışmada, AISI 4140 çeliğinin yüzeyi gaz tungsten ark (TIG veya GTA) tekniği kullanılarak SiC ve C tozları ile modifiye edilmiştir. Kaplanan malzemelerin mikroyapılarında işlem şartlarının değiştirilmesiyle, ara yüzeye doğru kalınlıkları değişen yönlenmiş dendritlerle birlikte, farklı Fe, C, Cr, Mo ve Si içerikli M7C3, M23C6, M2C, M3C, Fe3C, Fe2C karbürleri elde edilmiştir. Aynı zamanda mikroyapılarda farklı grafit taneciklerine de rastlanılmıştır. Sertlik değerleri yapıdaki mevcut faz ve karbürlerin varlığından dolayı önemli ölçüde artmıştır. Mikrosertlik değerleri üst tabaka kalınlığı boyunca 800-1400 HV arasında değişim gösterirken, ara yüzeye doğru gidildikçe sertlik değerlerinde bir azalma görülmüştür. En yüksek sertlik (1386 HV); 0,55 cm/s üretim hızında, 1-0,2 g/s SiC/C toz yedirme değerinde ve 28,6 kJ/cm enerji girdisi ile üretilen kaplama tabakasından elde edilmiştir.

Anahtar Kelimeler:

TIG yöntemi, karbür, dendrit

Investigation Of Microstructure Of Hardfaced AISI 4140 Steel By TIG Welding Process

In this study, a AISI 4140 steel surface was modified with SiC and C alloying powders by using of a gas tungsten arc (TIG or GTA) welding process. The results obtained from microstructural investigations indicate that the dendritic solidification resulting from eutectic reaction was observed in the modified layers together with the formation of M7C3, M23C6, M2C, M3C, Fe3C, Fe2C carbides at different shapes and rates. Additionally, different graphite precipitates were found in the microstructures of specimens. Hardness values of the coating layers increased because of existing phase and carbides in the microstructure. Hardness values of materials changed between 800-1400 HV along the modified layer then it decreased in interface regions. The highest hardness on coated layers measured as (1386 HV) which was produced at 0,55 cm/s production speed, 28,6 kJ/cm energy input and 1-0,2 g/s SiC/C powder content, respectively.

Keywords:

TIG method, carbide, dendrite,

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