Scientific journal
Scientific Review. Technical science
ISSN 2500-0799
ПИ №ФС77-57440

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IMPROVEMENT OF LARGE-SIZED DIES DURABILITY

Gotlib B.M. 1 Sergeev R.F. 1
1 Ural state university of railway transport
A study on the precision of die forging of special steels and the durability of forming dies is presented for large-sized dies when forged on high-pressure vertical hydraulic presses. The precision is increased with a profiling of the die’s pressure face followed by a cyclic hardening. The die is hardened by the induction of residual stress, which allows the die to operate within elastic deformation instead of elastic-plastic deformation. Two 5HNM steel samples were hardened by the cyclic tension forces of 150 and 200 MPa under the temperature of 500 °C. From 10 to 20 cycles were required for the samples to start showing elastic deformation. When the temperature was raised to 600 °C no hardening was observed under the stress of 150 MPa. A technique for profiling and cyclic hardening of dies produced of 5HNM steel is proposed. The die was tested on an industry-grade 300 MN press by upsetting 300 mm disks of H15N5D2T steel. The plastic deformation of the die bed contour amounted to 1 mm.