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<p>Real-time observations of microstructure evolution during hot deformation of steel are reported for the first time. This has been possible by the application of laser-ultrasonics (LUS) whilst deforming specimens in compression using the Gleeble 3800 thermomechanical simulator. A single test run by GLUS can provide a vast quantity of data which would require innumerable conventional experiments. The test material was a standard high strength low alloy (HSLA) steel from industrial production. Deformation temperatures were in the range from 950&#xa0;°C to 1175&#xa0;°C and the strain rates in compression were between 0.1 and 0.75&#xa0;s<sup>−1</sup> with measured parameters of applied stress, austenite grain size and also longitudinal ultrasonic wave velocity which gives an indication of the texture changes. Although the present results do not reveal any completely unexpected behaviour they provide a detailed description of the microstructural changes. Refinement of the austenite grains takes place through dynamic recrystallisation (DRX) during loading. If this process has not gone to completion when deformation ceases, it is followed by static recrystallisation which leads to a further reduction in the grain size. However, if the structure is fully transformed by DRX the following metadynamic recrystallisation occurs with little further change in the grain size. After longer holding times general grain growth becomes apparent for all conditions of deformation temperature and strain rate. For all these conditions it is found that the texture strengthens during deformation and weakens on subsequent annealing.</p>

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Investigation of Dynamic Recrystallisation of Steel During Hot Compression Using Gleeble and Laser-Ultrasonics (GLUS)

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年5月31日

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  • Mikael Malmström,
  • Linda Bäcke,
  • Hans Magnusson,
  • Johan Lönnqvist,
  • Bevis Hutchinson

摘要

Real-time observations of microstructure evolution during hot deformation of steel are reported for the first time. This has been possible by the application of laser-ultrasonics (LUS) whilst deforming specimens in compression using the Gleeble 3800 thermomechanical simulator. A single test run by GLUS can provide a vast quantity of data which would require innumerable conventional experiments. The test material was a standard high strength low alloy (HSLA) steel from industrial production. Deformation temperatures were in the range from 950 °C to 1175 °C and the strain rates in compression were between 0.1 and 0.75 s−1 with measured parameters of applied stress, austenite grain size and also longitudinal ultrasonic wave velocity which gives an indication of the texture changes. Although the present results do not reveal any completely unexpected behaviour they provide a detailed description of the microstructural changes. Refinement of the austenite grains takes place through dynamic recrystallisation (DRX) during loading. If this process has not gone to completion when deformation ceases, it is followed by static recrystallisation which leads to a further reduction in the grain size. However, if the structure is fully transformed by DRX the following metadynamic recrystallisation occurs with little further change in the grain size. After longer holding times general grain growth becomes apparent for all conditions of deformation temperature and strain rate. For all these conditions it is found that the texture strengthens during deformation and weakens on subsequent annealing.