Microstructure Control and Structure Analysis in the Semi-Solid State of Different Feedstock Materials for the Bearing Steel 100Cr6

Abstract:

The bearing steel 100Cr6 in the forged and hardened condition is of great importance in industrial use. Escaping the geometry restrictions of conventional forging, the application of semi-solid metalworking (SSM) offers significantly increased design freedom. Using conventionally available rolled feedstock material with carbide banding, however, results in a higher segregation tendency during thixoforging, and thus special attention was paid to the feedstock’s “quality”. To achieve a fine-grained, globular microstructure in the semi-solid state, castings with and without the addition of 100 ppm titanium were compared with the hot rolled material. With its inherent nitrogen Ti forms TiN particles, which reduce grain-growth in austenite. The results indicate that TiN precipitates strongly affect grain growth during solid state processing, but the grain size in the semi-solid state can only be influenced for short process times. Generally the cast feedstock materials possess smaller globulites in the semi-solid state compared to forgings, so that a reduction of the sponge effect and a minimization of the segregation in produced components are expected. Since the cast material already showed a fine-grained, globulitic microstructure, the use of TiN is not recommended because of the possible negative influence of TiN on the dynamic mechanical properties.

• Periodical: Solid State Phenomena (Volumes 116-117)
• Pages: 177-180
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.116-117.177
• Online since: October 2006
• Authors: Wolfgang Püttgen, Wolfgang Bleck, B. Hallstedt, Peter J. Uggowitzer
• Keywords: 100Cr6, Semi-Solid Metal (SSM) Forming, Steel, Thixoforming, Titanium Nitride TiN

References

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DOI: 10.1016/s0364-5916(02)00037-8