EKSTRA SERT AŞINMA DİRENÇLİ HARDOX 600 ÇELİĞİNİN KURU-KAYMA AŞINMA DAVRANIŞI

Abstract

Bu çalışmada, ekstra sert aşınma dirençli Hardox 600 çeliğinin kuru-kayma aşınma davranışı incelenmiştir. Deneyler ball-on-disk aşınma aparatında ileri-geri doğrusal hareket modunda gerçekleştirilmiştir. Numuneler 6, 7.5 ve 9 mm/s kayma hızlarında ve 3, 5 ve 7 N luk yükler altında aşındırılmıştır. Aşındırıcı olarak 6 mm çapında WC bilya kullanılmıştır. Numune hacim kayıplarının hesaplanmasında 3B profilometre görüntüleri kullanılmıştır. Aşınma yüzeylerinin incelenmesinde SEM mikrograflarından yararlanılmıştır. Yapılan deneysel çalışmalar sonucunda artan yük ve kayma hızına bağlı olarak hacim kayıplarının arttığı, ancak bunun yanı sıra artan yükle birlikte numune sürtünme katsayı değerinin düştüğü görülmüştür. Bununla birlikte değişen yük ve kayma hızına bağlı olarak numune yüzeylerinde meydana gelen aşınma mekanizmalarının farklılık gösterdiği gözlenmiştir.

Hardox steels have high strength and wear resistance. So, they are widely used in the automotive, mining, construction, agricultural, and ore processing industries. For this reason, the wear mechanisms on the machine parts, equipment, and machine tools exposed to harsh working conditions are performed as primarily abrasive and adhesive phenomena. In this study, the dry-sliding wear behavior of extra-hard wear-resistant Hardox 600 steel with chemical composition (% 0.4 C, % 0.56 Si, % 1 Mn, % 1.2 Cr, % 1.5 Ni, % 0.60 Mo, % 0.015 P, % 0.010 S) was investigated. The experiments were carried out in a ball-on-disk type tribometer device using reciprocating mode. The samples were abraded at sliding speeds of 6, 7.5, and 9 mm/s and under loads of 3, 5, and 7 N. A WC ball with a diameter of 6 mm was used as an abrasive. 3D profilometer images were used in the calculation of sample volume losses. SEM micrographs were used to examine wear surfaces. As a result of the experimental studies, it was observed that volume losses increased depending on the increasing load and sliding speed. However, it was determined that the friction coefficient values decreased with the increase in load, and it was evaluated that the main reason for this was the oxide layer caused by the temperature increase caused by friction in the contact area. It was determined that oxidation on the contact surface increased especially at low load and high sliding speed. In addition, the normal and tangential shear stresses that increased with the increasing load increased the plastic deformation, and the surface became flatter and less rough, reducing the friction coefficient. In addition, it was observed that the wear mechanisms occurring on the sample surfaces differed depending on the changing load and sliding speed. With the increase in load, first delamination, then adhesion and plastic deformation type wear mechanisms were detected.