Fatigue Properties and Section Analysis of Mod. SKD11 Nitrogen Ion Implantation Cold Work Mold Steel
Introduction
Nitrogen ion implantation can be used to improve the fatigue properties of cold worked mold steel. In the present study, Mod. SKD11 steel was used to investigate the fatigue properties of nitrogen implanted surface and the relation between microstructure and fatigue properties.
Experimental Procedure
To study the influence of nitrogen ion implantation on the fatigue properties, Mod. SKD11 steel specimens were attached to a cold working mold and subjected to surface nitrogen ion implantation. After nitrogen implantation, cross-section analyses were used to examine the microstructural parameters such as average grain size, porosity, and hardness. The fatigue properties were evaluated by means of a special fatigue test, where specimens were subjected to a cyclic load.
Fatigue Results
It was found that nitrogen ion implantation increased the fatigue limit of Mod. SKD11 steel specimens by approximately 20 percent compared to untreated specimens. The fatigue limit was also significantly affected by the nitrogen ion implantation depth, with higher depths producing a greater fraction of the increase. Furthermore, it was observed that the fatigue limit was further enhanced if a higher dose of nitrogen was used during implantation.
Cross-Section Analysis
It was observed that nitrogen implantation was associated with a decrease in average grain size and a reduction in porosity and hardness. However, the degree of these changes varied with the depth and dose of nitrogen implantation. Specifically, the average grain size decreased to a minimum at the highest dose of nitrogen, while the porosity and hardness decreased with increasing dose and deeper implantation depths.
Conclusion
In conclusion, it was found that nitrogen ion implantation was effective in improving the fatigue properties of Mod. SKD11 steel compared to untreated specimens. The microstructural changes observed as a result of nitrogen implantation suggest that these changes may be related to the improved fatigue properties. Further research could be conducted to further examine this relationship.
