EXPERIMENTAL INVESTIGATION ON CRYOGENIC TREATMENT OF MACHINE TOOLS (DRILL BIT)
Author’s Name : M Mathanbabu | R Rahul | K Saravanan | A S Sathya
Volume 05 Issue 03 Year 2018 ISSN No: 2349-3860 Page no: 5 – 8
Tool wear studies of friction stir welding (FSW) is imperative since FSW is of late extended to Cu, Mg, SS, Ti and MMC besides Al. H13 tool steel is the widely used tool material in FSW. Carbide forming elements like Cr, W, V, and More added to steel ingots to improve the wear resistance. These carbides are not uniformly distributed in the ingot matrix because of macro segregation. Steels produced by P/M route have better wear resistance compared to ingot steels since segregation is avoided. Cryogenic treatment of tool steels also improves the wear resistance. Hence, the present study aims at comparing the wear behaviour of AISI H13 tool steel and Bohler K390 P/M steel (9 % V) before and after cryogenic treatment. Friction stir welding (FSW) is carried out at a constant rotation speed of 1200 rpm and at traverse speeds of 50 mm/min with a tool tilt of 3° for a weld length of 14 cm on 3 mm thick copper plate. The tool design chosen for this study is a simple tool with a concave shoulder of 15 mm diameter and a plain pin with 5 mm diameter. It was found that P/M tool and cryogenically treated H13 tool could withstand very high heat input conditions and possess better wear resistance compared to the wrought H13 tool steel. This is attributed to the uniform distribution of carbides and difference in thermal conductivity of the tools.
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