INVESTIGATION ON WEAR-RESISTANT COATINGS FROM DIFFUSION-ALLOYED AUSTENITIC STEEL OBTAINED BY PLASMA SPRAYING AND SUBSEQUENT LASER PROCESSING

Abstract

The paper describes investigations on wear-resistant coatings from diffusion-alloyed austenitic steel obtained while using plasma spraying and subsequent laser processing. It is common knowledge that majority of machine parts and equipment has been out of service due to wear of surface layer. Application of diffusion-alloyed powder ПР-Х18Н9 based on austenitic steel while using combined technology including plasma spraying and laser infusion makes it possible to obtain qualitative coatings with high operational characteristics. The coating has a homogeneous structure with characteristic dispersive finely-dendrite formation. While using various powder boronizing modes and laser processing it is possible to control a porosity (0,23–4,70 %) because the given factor is considered as an inherited parameter and it is influenced not only by laser processing characteristics but by powder boronizing time. It has been established that the least deformations and internal stresses are formed in the coating in the case when self-fluxing diffusion-alloyed powder has been applied for 3 hours. It has been revealed that there is a sharp increase in micro-hardness at the depth of 150-400 µm from the surface for a specific energy of 100-300 J/mm2 regardless of boronizing time. Coatings can be successfully applied in industry because after laser infusion the required mechanical processing of parts will not worsen operational characteristics when less hard coating layer is removed. Tests of parts under conditions of dry sliding friction without lubrication have shown an increase of wear-resistance by 3.0-3.2-fold while preserving corrosion-resistance.

Keywords

• diffusion-alloyed powder
• plasma spraying
• laser processing
• stresses
• deformations
• wear resistance