Influence of the heating rate on sintering shrinkage of plain iron

ABSTRACT

The effect of heating rate on shrinkage of plain iron was investigated on green specimens with different green densities: 6.5, 6.9 and 7.3 g cm⁻³. On increasing the heating rate, the anisothermal shrinkage in the alpha field starts at higher temperatures but its amount does not change. The activation energy corresponds to that of dislocation pipe diffusion, confirming the role of the structural defects accumulated in the particles during cold compaction. The isothermal shrinkage increases on increasing the heating rate, likely due to the effect of surface diffusion at lower temperatures that reduce the driving force, without a measurable effect on shrinkage. The effect of green density is the same for anisothermal and isothermal shrinkage, with a minimum (in absolute value) at the intermediate green density.

KEYWORDS:

• Sintering shrinkage
• heating rate

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No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Silvia Baselli

S. Baselli received the PhD in Materials, Mechatronics and System Engineering in 2020 from University of Trento and is currently post-Doc at the Department of Industrial Engineering, Trento University. Her reserach activity is focused on the study of sintering of prior cold compacted metallic powders. She received the Master Theis award from EPMA in 2017.

Alberto Molinari

A. Molinari received the Ph.D. degree in Metallurgical Engineering in 1986 from Torino Technical University, Italy. He is currently a full professor of the Department of Industrial Engineering, Trento University. His main research activity is devoted to the study of mechanisms of cold compactionand of sintering of metallic powders, of mechanical properties of sintered steels, and to the application of AM in medical industry. He received Honor Ph.D. by University-Carlos III, Madrid in 2016 and by Cracow Technical Universityin 2019, and is Fellow of EPMA and of APMI.