The effect of H900 and H1150 heat treatment on the machinability of 15-5 PH stainless steel

15-5 PH steel is a stainless steel with a martensitic base that increases in hardness, hardness and strength with the aging process. The high hardness and low thermal conductivity of this steel cause severe wear of the tool and high cutting force and increase the roughness of the workpiece surface. The common method in the production of parts of this material is machining in solution (dissolution) with a maximum hardness of 35HRC.Then, in order to increase the strength, hardening operations are used. In this paper, in order to analyze the effect of hardening heat treatment on the machinability of this steel, two very common heat treatments H900 and H1150 were performed on the mentioned steel and the turning results in each operation were compared with the turning results in solution mode.Lathe force was measured during the process using a dynamometer and surface roughness of the parts after turning. The results showed that the best conditions in terms of reducing lathe force and surface roughness are obtained in H1150 mode. A comparison between turning in the H900 and solution modes also shows that, although the average turning force in the H900 mode is approximately 22% higher than the solution mode.But the average surface roughness, in the H900 mode, is 17% higher than the solution mode. In addition, turning in the H900 mode reduces defects such as lateral slippage of the workpiece material and plowing by the tool compared to lathe turning.