Possibilities and constraints of implementing starch consolidated high speed steel in prototyping
Paper in proceedings, 2006

In the starch consolidation (SC) process, a water-based slurry containing powder, starch, dispersant and thickener is used to fabricate near net-shape green bodies that are de-binded and further consolidated by sintering. In this study, gas atomized M3/2 as well as high and low carbon V-rich M4 type high speed steel powder (<150 mu m) are considered, Both material types undergo high volumetric shrinkage during super-solidus liquid phase sintering enabling them to reach near full density. The analyses and the review cover different process aspects like: recipe optimisation, post-gelatinization drying, de-binding and sintering. A SC recipe consisting of 58 vol.% powder, 3 vol.% starch, 1 vol.% dispersant and a thickener solution resulted in a density of >98% than what is theoretically stated after sintering. It is found that the success of the post-gelatinization drying procedure depends on the smoothness of mould material and controlling powder oxidation. The best combination was freeze drying the slurry in a silicon rubber mould. For V-rich alloys a total or partial control of eutectic carbides in the final microstructure could be realized for vacuum and nitrogen sintering atmospheres, respectively.

super-solidus liquid phase sintering

starch consolidation

prototyping

Author

Henrik Borgström

Chalmers, Materials and Manufacturing Technology, Surface and Microstructure Engineering

P. Harlin

Dalarna university

M. Olsson

Dalarna university

T. Paiar

University of Trento

Y. Wang

Karlstad University

Lars Nyborg

Chalmers, Materials and Manufacturing Technology

Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

0921-5093 (ISSN)

Vol. 475 1-2 34-38

Subject Categories

Materials Engineering

DOI

10.1016/j.msea.2006.12.142

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