Improved Cold Formability by Thermo‐Mechanical Rod Rolling

Kienreich, Robert; Buchmayr, Bruno

doi:10.1002/srin.200300191

Cited by 4 publications

(3 citation statements)

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“…Experimental studies, mathematical models and industrial rolling of rods and bars are established . Starting from a square billet (130 × 130 mm) to a rod diameter of 5,5 mm in more than 20 passes requires a model for the temperature evolution during rolling and a complete prediction of the strains in each pass coupled with microstructural models for the prediction of static and dynamic recrystallization, the austenite grain size, and transformation kinetics at the Stelmor conveyor.…”

Section: Tm‐processing Applied To Other Forming Processesmentioning

confidence: 99%

“…Prediction of temperature history during rod rolling combined with the prediction of austenite grain size and the amount of microstructural constituents …”

Section: Tm‐processing Applied To Other Forming Processesmentioning

confidence: 99%

“…Effect of reduced finishing temperature and cooling rate during rod rolling of a spring steel showing an improved ductility for a lower rolling temperature …”

Section: Tm‐processing Applied To Other Forming Processesmentioning

confidence: 99%

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Thermomechanical Treatment of Steels - A Real Disruptive Technology Since Decades

Buchmayr

2017

steel research int.

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The basic concept of thermomechanical treatment (TMT) or thermomechanical controlled processing (TMCP) is responsible for the development of many advanced steel grades with improved mechanical properties during the last 50 years. A retroperspective view, an explanation of the most important influencing factors and a presentation of the enormous benefits for the costumer are given in this review. A sound knowledge on the synergism of recrystallization, precipitation, and transformation phenomena forms the basis to produce fine, homogeneous microstructures with improved properties. Starting from structural steels, improvements can be achieved with respect to higher strength and toughness values combined with better weldability and formability, mainly based on reduction of carbon content and finer grain sizes. The benefits in the application areas are described in detail. TMCP is not only used for flat products, but also for long products and forgings of different steel grades. Physical simulation and modeling contribute significantly to these developments, which also form the basis for computer-aided control or real-time online-models. In the next years, a complete shift to cyber physical systems (CPS) is predicted, which needs an aligned education effort. REVIEW A Brief Historical ReviewSince the mid-sixties, steel mills began to produce fine grained structural steels by lowering the final rolling temperature. Based on fundamental research in Germany, USA, UK, Germany, and Japan, the fundamental understanding was further developed in metallurgical laboratories. Pioneers at that time were Haneke, [10] Schmidtmann, [11,12] Meyer, [13,14] Kaspar, [15][16][17][18][19][20][21][22][23][24] Streißelberger, [9,15,[25][26][27] DeArdo, [28,29] Jonas, [30][31][32][33] Sellars, [34][35][36][37] Hodgson, [38][39][40][41][42] Tamura und Tanaka, [43] Saito, [44] Ouchi, [45] Militzer, [46,47] and many others. The basic idea was to improve the strength and toughness behavior of structural steels by grain refining. Compared to conventional hot rolling at high rolling temperatures, the new steels were rolled at lower final rolling temperature. It was found that repeated recrystallization of the austenite structures leads to a decrease of grain size, but there is a limit, which is difficult to overcome. Deformation at temperatures, where no recrystallization takes place was successful in the conditioning of austenite having a dense population of glide planes, high dislocation density, and a high intrinsic energy, which provided a high density of nucleation sites for the transformation products of austenite.At the beginning, mainly ferrite plus pearlite microstructures were considered and later the role of rapid cooling became an additional opportunity to increase the strength level.Higher cooling rates or higher undercooling increase the driving force and with a lower diffusivity a finer microstructure like bainite and martensite can be reached.A comparison of the contributions of the strengthening mechanism in a commercial hot rolle...

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Section: Tm‐processing Applied To Other Forming Processesmentioning

confidence: 99%

“…Prediction of temperature history during rod rolling combined with the prediction of austenite grain size and the amount of microstructural constituents …”

Section: Tm‐processing Applied To Other Forming Processesmentioning

confidence: 99%

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Thermomechanical Treatment of Steels - A Real Disruptive Technology Since Decades

Buchmayr

2017

steel research int.

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Lehrstuhl für Umformtechnik

Buchmayr

Harrer

Sommitsch

2006

Berg Huettenmaenn Monatsh

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Hauptforschungsgebiete des Lehrstuhls fª Umformtechnik sind die physikalische und numerische Simulation von Umformprozessen, wie Walzen, Schmieden, Strang-und FlieBpressen, -¡ u.a., sowie die Vorhersage der Gefª und der mechanischen Eigenschaften und die Charakterisierung der Umformbarkeit metallischer Werkstoffe.Chair of Metal Forming. Main research areas are the physical and numerical simulation of metal forming processes, like rolling, forging, extrusion and cold forming, drawing etc., as well as the prediction of the microstructural development and mechanical properties and the characterization of the formability of metallic materials.

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Aktuelle Entwicklungstrends und zukünftige Herausforderungen im Bereich der Umformtechnik

Buchmayr

2015

Berg Huettenmaenn Monatsh

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Improved Cold Formability by Thermo‐Mechanical Rod Rolling

Cited by 4 publications

References 1 publication

Thermomechanical Treatment of Steels - A Real Disruptive Technology Since Decades

Thermomechanical Treatment of Steels - A Real Disruptive Technology Since Decades

Lehrstuhl für Umformtechnik

Aktuelle Entwicklungstrends und zukünftige Herausforderungen im Bereich der Umformtechnik

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