PROTECTION 500 (P 500) ÇELİĞİNİN KURU-KAYMA AŞINMA DAVRANIŞI

Abstract

Bu çalışmada, Protection 500 (P 500) çeliğinin iki farklı kayma hızında (4 ve 8 mm/s) ve üç farklı yük (10, 20 ve 30 N) altında kuru-kayma aşınma davranışı incelenmiştir. Deneyler ball-on-disk aşınma aparatında ileri-geri hareket modunda gerçekleştirilmiştir. Aşındırıcı olarak 6 mm çapında WC bilya kullanılmıştır. Test numunelerinin aşınma hacim kayıplarının hesaplanmasında 3D profilometre görüntüleri kullanılmıştır. Aşınma testleri sonrasında numune yüzeylerinde ortaya çıkan aşınma mekanizmaları SEM ve EDS analizleri ile değerlendirilmiştir. Yapılan deneysel çalışmalar sonucunda artan yüke ve kayma hızına bağlı olarak hacim kayıplarının arttığı ancak kayma hızının aşınma mekanizması üzerinde daha etkin bir parametre olduğu görülmüştür. Düşük kayma hızlarında oksidasyon ana aşınma mekanizması olurken yüksek kayma hızında oksidasyon, yorulma ve plastik deformasyon aşınma mekanizmaları görülmüştür.

Protection 500 (P 500) is a ballistic penetration-resistant armor steel with high yield strength (1300 MPa) and tensile strength (1600 MPa) as well as high hardness (500 HBW). It is also preferred in parts exposed to high wear in service conditions, such as mining machines, crushers, excavators, dumper bodies, bulldozer blades, and chute-feeders. Since the loads and friction conditions to which the machine parts and components used in the mentioned harsh service conditions are exposed also vary considerably, evaluating the wear performance of these materials is also an important issue. In this study, the dry-sliding wear behavior of P 500 steel was investigated at two different sliding speeds (4 and 8 mm/s) and under three different loads (10, 20, and 30 N). The wear experiments were carried out in reciprocating mode on a ball-on-disc wear apparatus. The contact pair used a WC ball with a diameter of 6 mm and a hardness of 19 GPa as the abrasive counter body material. Thus, the aim was mainly to determine the wear characteristics of P 500 by limiting the surface mechanisms related to the wear of the abrasive part. 3D profilometer images were used to calculate the wear volume loss values of the test samples. The wear mechanisms occurring on the sample surfaces after the wear tests were evaluated using SEM and EDS analysis. As a result of the experimental studies, it was observed that the volume losses increased with increasing load and sliding speed. In addition, increased load and sliding speed resulted in a limited decrease in the CoF value. The main reason for this case is considered to be an increase in friction-induced heat and plastic deformation due to increasing load and sliding speed, resulting in a smoother worn surface. Besides, the sliding speed was detected as a significant parameter affecting the wear mechanism. While oxidation was the primary wear mechanism at low sliding speeds, oxidation, fatigue, and plastic deformation wear mechanisms were observed at high sliding speeds.