Influence of Reheating Conditions on Austenite Grain Growth

Kvačkaj, Tibor; Nemethova, Lenka; Mišičko, Rudolf; Pokorný, Imrich

doi:10.1515/htmp.2011.110

Cited by 3 publications

(6 citation statements)

References 9 publications

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“…%) is the nitrogen content; A, B (-) are the thermodynamic constants; and T (°C) is the dissolution temperature of the precipitate. A detailed description of the solubility of precipitates is discussed in [ 98 ]. Graphical interpretation of the effect of reheating temperature and holding time on the solubility of precipitates and changes in austenite grain size diameters is shown in Figure 6 .…”

Section: Resultsmentioning

confidence: 99%

“…Figure 6 shows that the strongest braking effect on austenitic grain growth was the result of Nb precipitates. The change in grain size is closely related to the coarsening or dissolution of the carbonitrides [ 98 ]. Steel grades without Nb showed higher values for austenite grain-size diameter, and the start of abnormal grain growth shifted to lower temperatures compared to those of Nb-bearing steels.…”

Section: Resultsmentioning

confidence: 99%

“…Also, general formula (4) of the authors [ 98 ] that describes the development of the austenite grain size being dependent on the reheating condition for HSLA C–Mn–Nb–V steel has the real form:

…”

Section: Resultsmentioning

confidence: 99%

“…Another mathematical formula describing normal and abnormal grain growth may have the general form [ 98 ]:

where: a 1 , a 2 , a 3 are regression coefficients depending on the reheating conditions; T Reh (°C) is the isothermal reheating temperature; and t Reh (s) is the holding time at T Reh .…”

Section: Introductionmentioning

confidence: 99%

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Overview of HSS Steel Grades Development and Study of Reheating Condition Effects on Austenite Grain Size Changes

Kvačkaj

Bidulská

Bidulský³

2021

Materials

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This review paper concerns the development of the chemical compositions and controlled processes of rolling and cooling steels to increase their mechanical properties and reduce weight and production costs. The paper analyzes the basic differences among high-strength steel (HSS), advanced high-strength steel (AHSS) and ultra-high-strength steel (UHSS) depending on differences in their final microstructural components, chemical composition, alloying elements and strengthening contributions to determine strength and mechanical properties. HSS is characterized by a final single-phase structure with reduced perlite content, while AHSS has a final structure of two-phase to multiphase. UHSS is characterized by a single-phase or multiphase structure. The yield strength of the steels have the following value intervals: HSS, 180–550 MPa; AHSS, 260–900 MPa; UHSS, 600–960 MPa. In addition to strength properties, the ductility of these steel grades is also an important parameter. AHSS steel has the best ductility, followed by HSS and UHSS. Within the HSS steel group, high-strength low-alloy (HSLA) steel represents a special subgroup characterized by the use of microalloying elements for special strength and plastic properties. An important parameter determining the strength properties of these steels is the grain-size diameter of the final structure, which depends on the processing conditions of the previous austenitic structure. The influence of reheating temperatures (TReh) and the holding time at the reheating temperature (tReh) of C–Mn–Nb–V HSLA steel was investigated in detail. Mathematical equations describing changes in the diameter of austenite grain size (dγ), depending on reheating temperature and holding time, were derived by the authors. The coordinates of the point where normal grain growth turned abnormal was determined. These coordinates for testing steel are the reheating conditions TReh = 1060 °C, tReh = 1800 s at the diameter of austenite grain size dγ = 100 μm.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

…”

Section: Resultsmentioning

confidence: 99%

“…Another mathematical formula describing normal and abnormal grain growth may have the general form [ 98 ]:

where: a 1 , a 2 , a 3 are regression coefficients depending on the reheating conditions; T Reh (°C) is the isothermal reheating temperature; and t Reh (s) is the holding time at T Reh .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Overview of HSS Steel Grades Development and Study of Reheating Condition Effects on Austenite Grain Size Changes

Kvačkaj

Bidulská

Bidulský³

2021

Materials

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“…Both the reheat temperature (RHT) and soaking time (t soak ) influence d 0 , although the RHT has a stronger influence on austenite grain growth than time [4]. The austenite grain size, d, affects both the recrystallisation and the phase transformation characteristics during processing and thus the final ferrite/pearlite microstructure and mechanical properties, particularly in air-cooled plates [4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

The Influence of Initial Grain Size and Strain Sequence of Slab Hot Rolling on the Austenite Evolution of Peritectic Microalloyed Plate Steels

Maubane

Banks

Stumpf

et al. 2014

AMR

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The influence of the strain sequence during slab hot rolling (also known as “roughing”) on the evolution of austenite in plain carbon, C-Mn-V and C-Mn-Nb-Ti-V steels was investigated. Reheating and roughing simulations were conducted in a Bähr deformation dilatometer using a constant austenitising temperature, constant soaking time and various heating rates and roughing strain sequences. Stress analysis was used to quantify the austenite softening behaviour and the prior austenite grain size was measured from quenched specimens. The austenite grains of the plain carbon steel were coarser than those of both microalloyed steels, with the C-Mn-Nb-Ti-V grade being the finest due to effective pinning of the grain boundaries. Pass strains greater than 0.2 were sufficient for initiation of dynamic recrystallisation (DRX) for the C-Mn and C-Mn-V steels and led to uniform austenite microstructure with austenite grain sizes less than 40µm after the roughing stage.

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Interrelationship between Hot Ductility and Particle Size in TiNb IF Steel

Konrádyová

Longauerová

Girman

et al. 2017

MSF

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The aim of this work was to observe the relationship between hot ductility and morphology, distribution and size of particles in TiNb IF steel after hot torsion testing at the critical temperatures of deformation with low as well as maximum values of plasticity. Transmission electron microscopy showed that the particles at all temperatures of deformation with minimum number of turns to failure e.g. 1132°C (33.72 rev.), 946°C (6.24 rev.), 637°C (5.54 rev.) as well as with maximum value of plasticity at 844°C (1726 rev.) were of globular, cuboid or elliptical shape. EDX analysis revealed that there were different types of particles such as carbides, sulfides, and carbonitrides of Ti and Nb, Al and Si oxides, Mn sulfides, and phosphides. Quantitative evaluation of particle size in the carbon extracted replicas showed 20% of total number of particles with size 2r = 30-39 nm and an average linear dimension = 42 nm at the deformation temperature of 1132°C. There were 28% of the particles with size 2r = 20-29nm and = 41nm at the temperature of 946°C while at the temperature of 637°C there were 29% of particles with size 2r = 20-29 and 26% with size 2r=10-19 nm and = 41 nm. In the case of maximum plasticity (1726 rev.) at 844°C, the presence of large particles was confirmed with = 105 nm size and 9% distribution in three size categories of 20-29, 30-39, 90-99 nm.

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Influence of Reheating Conditions on Austenite Grain Growth

Cited by 3 publications

References 9 publications

Overview of HSS Steel Grades Development and Study of Reheating Condition Effects on Austenite Grain Size Changes

Overview of HSS Steel Grades Development and Study of Reheating Condition Effects on Austenite Grain Size Changes

The Influence of Initial Grain Size and Strain Sequence of Slab Hot Rolling on the Austenite Evolution of Peritectic Microalloyed Plate Steels

Interrelationship between Hot Ductility and Particle Size in TiNb IF Steel

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