Exploring the influence and mechanism of hardfacing STL12 on impact wear performance at high temperature and heavy load

Abstract

As one of the most important contact pairs of an engine, the performance improvement of the valve and seat insert contact pair is of great concern. In this study, commonly used industry tempered seat inserts and hardfacing seat inserts were selected (named tempered group and hardfacing group respectively). The impact wear performance test was carried out, under conditions consistent of temperature of 650 °C, load of 30 kN, frequency of 12 Hz, and stroke of 1 mm. The wear process of the wear zone was investigated using 3D scanner, optical microscope (OM), scanning electron microscope (SEM), and X-ray photo-electron spectroscopy (XPS). The wear mechanism of the wear area was analyzed according to macro profile and micro wear morphology. The results showed that after the impact test, a layer of oxide film was formed on the surface of the hardfacing seat insert, which isolated direct contact of the valve and the seat insert, greatly improving the wear performance of the pairs. In addition, the hardness of the hardfacing seat insert was higher than the tempered seat insert, this further reduced the weight loss between the contact pairs. The weight loss of hardfacing group was 0.36 g and tempered group was 1.62 g, the weight loss of hardfacing group was reduced by 77.78 % compared with that of tempered group. So in conclusion the impact wear performance of the hardfacing pair is better than the tempered pair.