Experimental investigation on microstructural and mechanical properties of quenched AISI 4145 sinter forged steel

Abstract

In the present investigation, microstructure and mechanical properties of sinter - forged AISI 4145 steel have been examined. Homogeneous powder blend of steel corresponding to AISI 4145 composition has been taken to prepare the compacts of 30 mm diameter with 1.0 aspect ratio on hydraulic press using suitable die assembly. Protective coated green compact preforms have been sintered at 1150^°C ± 10^°C for a period of 90 min. Subsequently, the sintered preforms have been hot upset forged to square cross-sectional bars (~13 mm × ~13 mm) with the length of 110 ± 5 mm. Further, the bars have been quenched in oil with and without homogenization. Mechanical properties such as tensile strength, yield strength, percentage elongation, and impact strength have been analysed. Optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies have been used to characterize the metallurgical features of the steel on different oil quenched condition. Microstructure reveals the ferrite, pearlite and non-equilibrium marten site structures in the sinter-forged low alloy steel. Sinter forged steel exhibits enhanced strength and hardness in homogenized oil quenched condition.