Shot peening process could create compressive residual stress and increase surface hardness and hence also used to improve material surface properties in case thermal effect is to be avoided. The shot peening process parameters such as pressure which result in different shot impact velocity could affect the compressive residual stress distribution which results in different post-process material properties. The ability to understand and predict the effect of process parameters on stress distribution could be very useful to control and obtain material properties as required. In this work, a shot peening process commercially available locally was investigated. The residual stress distribution after shot peening of SKD11 was studied using the finite element (FE) technique. A single shot impact was simulated. A maximum velocity with a miximum impact angle was assumed. The computational predictions showed higher compressive residual stress developed with increasing shot velocity as expected due to higher impact energy. However, experimental results suggested that the process arrangement and machine control highly affect the properties of the material after process. The compressive residual stress and surface hardness obtained experimentally was almost unchanged with an increase in pressure from 0.35MPa to 0.6MPa. It was found that, due to machine arrangement, an increase in impact velocity at higher pressure was relatively small and did not observed in all effected area due to fixed arrangement of nozzle and samples. Hence, research results suggested that a detail computational methodology including the effect of unevent impact velocity and impact angle should be employed to increase the predictive ability of the FE model. The current work could be extended to include such effects with no major difficulty to develop useful information for the design of shot peening process for any specific machine and arrangement.

A new configuration of chromizing process was developed by separating Cr powder from NH4Cl. FC220 gray cast iron specimens were chromized in this new experimental setup at 450, 550, 650,750, 850 and 950°C during 13 hours in order to study the possibility of chromizing at “low” temperature. The chromized specimens were examined using Scanning Electron Microscopy (SEM), macro-hardness, micro-hardness, compression test and salt spray test. The results shows that the specimen chromized at 650°C gives the best compromise between the corrosion resistance and the hardness of the FC220 with 1.73 ڌm of thickness of the chromized layer. However, after 13 hours of the process, the hardness of the FC220 specimens decreased considerably from 93 HRB to 64.2 HRB (31%).