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Experimental Characterisation of TRIP Effects of 31CrMoV9 for Hot Forming

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Abstract:

During the hot bulk forming of long parts, inhomogeneous distributions of deformations and temperatures occur. The gradients of these distributions lead to complex, overlaying residual stresses, which can cause critical geometric deviations and mechanical failures. Common finite element (FE)-simulations for designing a process are in principle capable to predict the thermal, mechanical and metallurgical effects, but require extended material models. Thereby, the total strain increment can be described through the partial strain components of the elastic, plastic, thermal transformation related and transformation plasticity strain. To allow the numerical prediction of the distortion of long hot formed parts, an experimental characterisation of the TRIP and backflow effects is presented for the steel 31CrMoV9. Time temperature transformation (TTT) and continuous cooling transformation (CCT) diagrams are determined with JMatPro and verified by means ofmicrostructure analysis and hardness measurements. Based on these diagrams, the transformation plasticity is investigated through dilatometric tests whereby tensile and compressive loads are applied during the phase transformation. The martensite phase transformation showed the highest amounts of TRIP strains, whilst the bainite transformation exhibited lower strains but a high tensile backflow strain. For perlite the beginning of the phase transformation was delayed and its duration extended due to the induced loads.

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Periodical:

Materials Science Forum (Volume 1186)

Pages:

25-36

DOI:

https://doi.org/10.4028/p-OanM4P

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Cite this paper

Online since:

April 2026

Authors:

Simon Peddinghaus*, Norman Mohnfeld, Johanna Uhe, Bernd Arno Behrens

Keywords:

Hot Forming, Material Characterization, TRIP

Funder:

The publication of this article was funded by the Leibniz Universität Hannover (LUH) / Technische Informationsbibliothek (TIB)

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* - Corresponding Author

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