Evaluation of machinability of hardened and cryo-treated AISI H13 hot work tool steel with ceramic inserts

• The lowest wear and Ra values were obtained in the turning of the CTT samples.
• The use of cutting fluid slightly improved the machinability of the tool steel.
• In terms of Fc, Ra and tool wear, CC650 inserts were superior to CC670 inserts under both machining conditions.
• The nose wear and crater wear were dominant for all ceramic inserts.
• Larger adhesions were observed on the crater zones of the CC670 inserts.

The positive effects of deep cryogenic treatment on the wear resistance of cutting tools and workpiece material are well known; however, no information has been reported about the effect on the machinability of cryo-treated tool steel in hard turning. In order to investigate the effects of cryogenic treatment on the machinability of hardened and cryo-treated tool steel, a number of investigations were performed on the hard turning of cryo-treated AISI H13 hot-work tool steel with two ceramic inserts under both dry and wet cutting conditions. Three categories of the hot-work tool steel were turned in the machinability studies: conventional heat treated (CHT), cryo-treated (CT) and cryo-treated and tempered (CTT). Experimental results showed that the lowest wear and surface roughness (Ra) values were obtained in the turning of the CTT samples. Additionally, in terms of main cutting force (Fc), surface roughness (Ra) and tool wear, Ti[C, N]-mixed alumina inserts (CC650) showed a better performance than SiC whisker-reinforced alumina inserts (CC670) under both dry and wet cutting conditions. The use of cutting fluid slightly improved the machinability of the tool steel.