Available online at www.sciencedirecLcom #',# ScienceDirect JOURNAL OF IRON AND STEEL RESEARCH, INTERNATIONAL. 2008, 15(5): 81-87 Sintered Fe-O. 8%C-1. O%Si-O. 4%Cu P/M Steel Preform Behaviour During Cold Upsetting A Rajeshkannan 1 , KS Pandey" , S Shanmugam" , R Nar ayanasamy" (1. Thiagarajar College of Engineering, Thiruparankundram, Madurai 625015, Tamil Nadu , India; 2. Maulana Azad National Institute of Technology, Bhopal 462007, Madhya Pradesh, India; 3. Department of Mechanical Engineering, National Institute of Technology, Tiruchirappalli 620015, Tamil Nadu , India; 4. Department of Production Engineering, National Institute of Technology, Tiruchirappalli 620015, Tamil Nadu , India) Abstract: Cold upsetting experiments were carried out on sintered Fe-O. 8 %C-1. 0 %Si-O. 4 %Cu steel preforms in or- der to evaluate their deformation characteristics. Powder preforms of 86 % of theoretieal density, with two different ratios of height to diameter, were prepared using a suitable die set assembly on a 1. 0 MN capacity hydraulic testing machine. Sintering was carried out in an electric muffle furnace for 1. 5 h at 1 150 'C. Each sintered compaet was subjected to incremental loading of O. 04 MN under dry friction condition till a crack appeared at the free surfaces. The experimental results were critically analysed, the stress as a function of strain and densification was obtained, then the work hardening behaviour was analyzed. It has been found that in the process of enhancing densification , strength and strain hardening is also induced during upsetting, but the work hardening behaviour is not homogenous- ly enhanced against strain and densification. Key words: cold upsetting; stress; height strain; densification; work hardening behaviour Powder metallurgy (P1M) processes provide techno-economic benefits over ingot metallurgy processes, the advantages being cost reduction, im- proved performance, design flexi bili ty , and the pro- duction of unique materials'{". The manufacturing processes for conventional P 1M parts consist of powder production, blending (if it is an alloy), compaction, and finally sintering. Such parts are used in application requiring low mechanical proper- ty levels'". Secondary processes, such as pressing or repressing, powder extrusion, powder rolling, and infiltration can be used to improve the mechani- cal properties of parts produced through convention- al P 1M rout el", Attraction and interest in net shape and near net shape manufacturing find P 1M to be a competitive method of manufacturing particular parts such as in the mass production of machine tool components-' '. Powder preform upsetting involves fabrication of a preform by conventional P/M route, followed by the conventional forging[5]. In general, the pre- form produced by this process will undergo large de- gree of plastic deformation with enhanced level of densification'P" (i. e. up to near net shape). Though the plastic deformation of P 1M parts is similar to that of the wrought materials, the additional complications are because of substantial amount of void fractions. Therefore, the mode of deformation in porous mate- rial is the function of both density and hydrostatic stress, which is not the case in wrought materi- als[8]. It has been reported-f that as the density in- creases, the imposed stress also increases. Similar- ly, increase of friction condition at die contact sur- faces during deformation substantially increases the stresses-v". With the application of axial compres- sive stress, the pores will collapse and ultimately close, at the same time density also enhances; whereas, with application of axial tensile stress, the pores will grow and densification will decrease'P", Apart from the regular enhancement of densification and stress due to induced strain during forging, usually por- ous material would also experience work hardening char- Biography: A RajeshkannanC1976-), Male, Doctor, Lectureship; E-mail: rkanitt@gmail.com. Revised Date: March 2, 2007