INVESTIGATION OF WEAR BEHAVIOR OF A PLASMA NITRIDED LOW ALLOY STEEL

Öz

Dry sliding wear tests were carried out on a plasma nitrided AISI 5140 low alloy steel. Plasma nitriding process variables included time, temperature, and nitrogen partial pressure of nitriding atmosphere. The plasma nitrided samples were characterized using microhardness techniques, optical and scanning electron microscopy. A pin-on-ring wear testing machine was utilized to assess the wear resistance of treated samples. The resulting wear loss was monitored as a function of sliding distance. Worn surfaces and collected wear debris were analyzed and dominant wear mechanisms were identified using microscopy techniques. It was found that the wear resistance improved considerably after the plasma nitriding process. However, for maximum resistance to wear, process parameters should be chosen so as to minimize the compound layer thickness and maximize the surface hardness and case depth.

Anahtar Kelimeler

• Dry sliding, Plasma nitriding, Microhardness, Worn surface

PLAZMA NİTRÜRLENMİŞ AZ ALAŞIMLI BİR ÇELİĞİN AŞINMA DAVRANIŞININ İNCELENMESİ

Öz

Plazma nitrürasyonu ile yüzeyi sertleştirilen, az alaşımlı AISI 5140 çeliğinin kuru sürtünmeli şartlarda aşınma deneyleri yapılmıştır. Plazma nitrürasyon işleminde, süre, sıcaklık ve ortamın azot yüzdesi işlem değişkenleri olarak kullanılmıştır. Yüzeyi sertleştirilen numuneler; optik ve taramalı elektron mikroskobisi ve mikrosertlik ölçümleriyle incelenmiştir. Numunelerin aşınma direnci, pim-halka deney düzeneği ile tespit edilirken, aşınma kaybı, sürtünme mesafesine bağlı olarak ölçülmüştür. Aşınmış yüzeyler ve aşınma artıkları mikroskobik olarak incelenerek aşınma mekanizmaları belirlenmiştir. Plazma nitrürasyonu ile aşınma dayanımında önemli artışlar elde edilmiştir. Maksimum aşınma dayanımı için, proses parametrelerinin, ince kompond (beyaz) tabaka, yüksek yüzey sertliği ve kalın difüzyon tabakası verecek şekilde optimize edilmesi gerektiği anlaşılmıştır

Anahtar Kelimeler

• Kuru sürtünme, Plazma nitrürasyonu, Mikrosertlik, Aşınma yüzeyi

Kaynakça

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