The study of EDM hole-drilling method for measuring residual stress in SKD11 tool steel

Deposition of DLC/oxynitriding Films onto JIS SKD11 Steel by Bipolar-pulsed PECVD

“…Since this material possesses high hardness and excellent wear resistance, it is usually used as a mold material and cutting tools. 1,2) In order to improve the tool life, many studies have focused on surface treatment as a method of protecting the internal material. 2) Nitriding is a thermo-chemical process with nitrogen diffusion, which leads to increase the surface hardness of the treated steels.…”

“…1,2) In order to improve the tool life, many studies have focused on surface treatment as a method of protecting the internal material. 2) Nitriding is a thermo-chemical process with nitrogen diffusion, which leads to increase the surface hardness of the treated steels. It reveals an effective improvement of thermal fatigue characteristics due to the effects of compressive stress and the hardened surface.…”

An Enhanced Calibration Scheme for the EDM Hole-Drilling Strain Gage Method for the Measurement of Residual Stress in Ferrous Materials

“…(1) should thus be the principal stress, IS,min and IS,max , induced by the hole-drilling operation. [10][11][12] Further step required was to explore the correlation between the hole-drilling induced stress and the thermal conductivity coefficient of the sample. Derivation of a more robust calibration scheme was aimed at.…”

“…Because the EDM condition of 12A/6 ms/30 ms ensured that the C sta coefficient is kept within 0.99-1 throughout the drilling operation, we suggest that this condition is optimal for EDM hole-drilling strain gage method. In previous studies [10][11][12] performed by the current group demonstrated that the hole-drilling induced stress ( IS ) was insensitive to the magnitude of the original residual stress within the specimens. Therefore, the IS value obtained from stress-free sample could be used to calibrate the value of the measured stress.…”

“…In previous studies by the current group, it was shown that the hole-drilling induced stress ( IS ) measured on stress-free specimens could be useful in compensating the measurement error. [10][11][12] However, it was also noted that the value of IS was highly sensitive to the working parameters such as pulse current and pulse-on duration. Thus it is required to specify the appropriate EDM working conditions in order to ensure the validity of the calibration.…”