Evaluation of the effect of hot forging and cooling conditions on the microstructure, hardness and machinability of medium carbon DIN 41Cr4 steel

This work DIN 41Cr4 tempered steel of hot forging applied focuses on the investigation of machinability of samples obtained by cooling in sand and air. The machinability evaluation has made in terms of main cutting force (Fc) and surface roughness (Ra). DIN 41Cr4 original material (OM), sand (SC) and air cooling (AC) samples has investigate microstructure and hardness changes. Turning experiments carried out at five different cutting speeds, four different feed rates and depth of cut. As a result, it has seen that the cooling environment of the samples after hot forging has a significant effect on the hardness and microstructure. The lowest main Fc was 131.54 N in the OM, while the highest Fc was 337.49 N in the AC sample in the turning of the samples. Evaluated in terms of Ra, the lowest Ra was obtained as 0.505 mu m in the AC sample, while the highest Ra was obtained as OM 1.793 mu m. It has been observed that the main Fc increases, while the Ra somewhat decreases depending on the increase in hardness and decrease in grain size. In general, SEM examinations, it has been seen that built-up edge (BUE) and breaks occurred in the cutting tools.