This research investigates and analyzes wear properties of 316 stainless steel before and after applying paste boronizing process and to investigate the effect of shot blasting process in enhancing boron dispersion into the steel. In order to enhance the boron dispersion into 316 stainless steel, surface deformation method by shot blasting process was deployed. Boronizing treatment was conducted using paste medium for 8 hours under two different temperatures which were 8500 C and 9500 C. Wear behaviour was evaluated using pin-on-disc test for abrasion properties. The analysis on microstructure, X-ray Diffraction (XRD) and density were also carried out before and after applying boronizing treatment. Boronizing process that had been carried out on 316 stainless steel increases the wear resistance of the steel compared to the unboronized 316 stainless steel. The effect of boronizing treatment together with the shot blasting process give a greater impact in increasing the wear resistance of 316 stainless steel. This is mainly because shot blasted samples initiated surface deformation that helped more boron dispersion due to dislocation of atom on the deformed surface. Increasing the boronizing temperature also increases the wear resistance of 316 stainless steel. In industrial application, the usage of the components that have been fabricated using the improved 316 stainless steel can be maximized because repair and replacement of the components can be reduced as a result of improved wear resistance of the 316 stainless steel.
Austempering is one of the trendiest heat treatment processes to promote the strength and toughness of ductile iron. However, such practice is complex because it involves using aqueous solutions as quenchant (salt bath solution). This study was conducted to analyse the heat treatment of the combination processes of annealing-austenitising and evaluate the correlation between microstructure constituent and hardness of the ductile iron. Ductile iron samples in form of double cylinder was produced by conventional CO2 sand casting method. The new heat treatment process was started by annealed at 873 K for 1.8 ks before being oil quenched. Subsequently, the samples were austenitised at austenitising temperatures 1123 K, 1173 K and 1223 K for 3.6 ks respectively before being immediately oil quenched to room temperature. A series of microstructure analysis tests, including optical microscopy and X-ray diffraction (XRD) was applied. Vickers microhardness tester was used to measure the hardness for each microstructure constituent. The results showed that ductile iron matrix transforms to martensitic during heat treatment of annealing-austenitising combination processes, which in turn contributes to increasing microhardness of martensite and the bulk hardness of ductile iron.
The aim of this study is to examine the effect of surface treatments involving shot blasting and paste boronizing on the microstructure, microhardness and density of 316L stainless steel. Shot blasting using glass beads was carried out prior to paste boronizing at fix boronizing temperature and soaking time of 850°C and 8 hours respectively. The results show paste boronizing produces boride layers that consist of FeB and Fe2B on the surface of 316L stainless steel with high hardness. Shot blasting on the other hand creates grain refinement on the metal’s surface which increases boron diffusion into the surface and improves the case depth of boride layers formed and also its hardness. Higher shot diameter used in shot blasting also influence in improving the case depth of boride layers produced and hardness of 316L stainless steel. The effect of shot blasting using a higher shot diameter and paste boronizing reduces the density of 316L stainless steel very slightly.
Powder carburising compound used for pack carburizing has limited potential in producing thicker case depth. Paste carburizing has proved to be an option to replace powder in conventional pack carburizing as it requires less time and temperature to diffuse carbon atoms, and thereby produce greater case depth. The correlation between case depth and mechanical properties using paste carburising is the objective of this paper where the relationship between case depth with mechanical and tribological properties using powder, paste 1:1 and paste 3:1 compounds at 1000°C for 9 hours are studied. Samples were subjected to microhardness tests, tensile tests and wear tests. Results showed paste 1:1 compound produced the highest case depth (>0.5 mm), allowing us to greater tensile strength, 6.61% and high wear resistance, 49%.