1 Determination of the Sintering Temperature in the Ultra High Frequency Induction Sintering System for Iron Based Powder Metal Compacts Uğur ÇAVDAR 1 , Mehmet Sadrettin ZEYBEK 2 , Muhterem KOÇ 2 , Aytaç ATAÇ 3 1 Celal Bayar University, Vocational School, Department of Machinery, 45400 Turgutlu-Manisa/Turkey. E-mail: ugur.cavdar@cbu.edu.tr 2 Celal Bayar University, Vocational School, Department of Material & Material Processing Technolojies, 45400 Turgutlu-Manisa/Turkey. E-mail: sadrettin.zeybek@cbu.edu.tr , muhterem.koc@cbu.edu.tr , 3 Toz Metal A.Ş., Istanbul/Turkey. E-mail: aytac@tozmetal.com . Abstract- In this study, powders of the iron based materials pressed at 400 MPa. Pressed powders were sintered with ultra-high frequency induction system. Induction system has 2.8 kW power and 900 kHz ultra-high frequency. This sintering process was applied to the powder metal (PM) compacts in argon atmosphere environment, at different sintering temperature from 900°C to 1300°C for 3 minutes. The optimum sintering temperature was investigated for ultra-high frequency induction sintering (UHFIS) process of the iron based PM compacts. Hardness and density tests results and micro structure and SEM images were investigated for different sintering temperature. Keywords- Iron based compacts, high frequency induction sintering, sintering temperature, and powder metallurgy. I. INTRODUCTION Iron and steel powders are produced for the manufacturing of sintered structural components. The worldwide consumption of these metal powder parts have been growing increasingly fast over the last forty years. In this period of time, iron and steel powders production methods are improved and application spectrum of these powders have been widened. Moreover, compacting and sintering techniques of powders have become more significant role in the production of specific metal parts. However, manufacturing methods have to consider cost effectiveness and high performance of the powder metal products. Cost-effectiveness and product quality are opposite poles in powder metal processing. When mechanical properties of products and complexity of geometry generally causes high costs. Therefore both features of being economical and high performance are primary purpose in the powder metal manufacturing processes. For sintering powder metal, induction heating method is developed to achieve this goal [1-7]. Some of the parameters are very important in the sintering process. These are sintering temperature and time, geometrical structure of the powder particles, composition of the powder mix, density of the powder compact, and composition of the protective atmosphere in the sintering furnace. The higher the sintering temperature and the shorter sintering time are desired to obtain mechanical strength between particles in the powder compact. But the correspondingly higher sintering temperatures are less economical because of higher maintenance costs for the sintering furnace. In iron powder metal industry, sintering conditions are 15-60 minutes at 1120-1150 °C [7]. In the sintering furnace, the protective atmosphere has undertaken several functions in the sintering. One of the missions is to protect powder metal parts from oxidation and to reduce possibly present residual oxides. But at the same time it is to prevent decarburization of carbon containing material. This shows the selection the correct atmosphere is one of the crucial points in the powder metal processes [8]. In iron powder metallurgy, hydrogen-nitrogen mixture, endogas or cryogenic nitrogen are commonly used for sintering atmospheres in the furnaces [1]. But in our study we did not used any inert gas for both sintering process. Kurt and Ateş [9], investigated iron based composition as in our work. They have found that densification is better for the samples sintered at 1150°C. In addition, Arık and Turker [10] investigated mechanical alloying of the same composition. They reported mechanical alloying resulted in the formation of finer powder particles containing homogeneously distributed carbon in iron. They said this process also caused the high deformation of particles, which increased the internal energy. In previous studies [11-16] iron and iron based powder metal compacts were sintered by medium frequency induction sintering. We cold pressed our powders as previous studies. This medium frequency induction sintered compacts had higher density than conventional *Corresponding author. E-mail address: ugur.cavdar@cbu.edu.tr , Tel: +90 533 629 5125, Fax: +90 236 314 4566