In order to improve the environments of forming operation, forging manufacturers have recently been switching from the graphitic water or oil-based lubricants to the non-graphitic water-based lubricants. When such lubricants are employed, however, shorter die life and poor metal flow into the cavity is observed, which leads to poor efficiency of operation.
Boron nitride has the lamellar structure similar to graphite. Therefore, lubricant performances of non-graphitic water-based lubricants including boron nitride were evaluated by the ring compression test and the spike test in the hot forging temperature range, and the following results were obtained:
(1) The friction shear factor for non-graphitic water-based lubricants with 1% addition of boron nitride decreased in ring compression test.
(2) Some non-graphitic water-based lubricants showed better performance of lubricity than that of graphite in the spike test. However, they required higher forging loads than that of graphite, resulting in the decrease of die life.
(3) Non-graphitic water-based hot forging lubricants compounded of several calboxylic acids showed an improvement of close adherence between die-material surface compared to that of a single calboxylic acid.
(4) Calboxylic acids gave a better stabilized perfomance at 1373K by inclusion of boron nitride.
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