Treatment methods for brittle and worn Hard alloy tap during cutting

2025-09-01 16:43:46

(1) The matrix of Hard Alloy tap should be rich in 79% WC, 15% TiC, and 6% Co. According to the above analysis, the content of WC, TiC, and Co is significantly low, especially the content of Co is almost close to that of YT30. Therefore, TOSG Hard alloy tap become brittle during cutting, and wear is mainly caused by damage. The decrease in Co content is related to high cutting temperature. High temperature intensifies the dispersion of Co, which is carried away by iron filings on the surface of Hard alloy tap, causing the matrix to lose Co and resulting in brittle addition of Hard alloy tap; 

(2) When the cutting temperature is high, chip oxidation is severe, as evidenced by the analysis of the composition of the worn surface. The surface of Hard alloy tap contains 31.62% oxygen and 6.58% iron, mainly composed of melted iron and iron oxide adhering to the worn surface. From the perspective of cutting process, at such cutting speeds and extremely high temperatures, it is generally impossible for YT15 hard alloy Hard alloy tap to be used, while nitrogen doped carbon coated Hard alloy tap can still be processed. This is due to the special physical and chemical functions of the coating. With the wear of the coating, the substrate is exposed and the Tap die wears out quickly; 

(3) At high temperatures, once the coating wears out, the dispersion of Co in the Tap die towards the workpiece and chips intensifies. Due to the reduction of adhesive phase, the brittleness of the Tap specifications increases. On the other hand, the dispersion of Fe in the workpiece and chips towards the Tap die also intensifies. The Fe dispersed into the Tap die will form a new low hardness brittle phase, resulting in a decrease in the overall function of the Tap die and exacerbating its wear.