Estimation of roles of matrix and NbC particles dispersed in surface layer of tool by PTA welding

摘要

Investigation has been carried out to estimate the roles of the matrix and NbC particles in the reinforced layer of a tool surface. In the last decade of the last century/In the 1990s it was reported that the reinforced layer of a tool surface by plasma-transferred-arc (PTA) welding using coarse NbC particles showed 10 times longer tool life in hot rolling of stainless steel and titanium. However, the roles of the matrix and NbC particles have not been investigated separately until now. In order to maximize the performance of the tool, it is important to optimize the structure of the welded surface layer, and for this purpose an optimum set of welding parameters of PTA should be selected. In the present work, major welding parameters are changed to clarify the roles of the matrix and NbC particles. The parameters changed are the size of NbC particles in the parent powder, the weight fraction of NbC in the parent powder, and the times of re-melting after PTA welding. For evaluation two types of sliding test are carried out: sliding tests under room temperature and at elevated temperature.