Precipitation hardening of HSLA steels

Militzer, Matthias; Poole, Warren J.; Sun, Weili

doi:10.1002/srin.199805550

Cited by 18 publications

(26 citation statements)

References 9 publications

(5 reference statements)

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“…Figure 15 compares the predicted peak times in the present steel with those for the other HSLA steels. 26) Clearly, peak times are shorter in the present steel consistent with the lower coiling temperature required. Apparently, the precipitation reaction that is primarily controlled by Ti diffusion in the present steel occurs quicker than similar reactions in steels that are predominantly microalloyed with Nb or V.…”

Section: Precipitation Strengtheningsupporting

confidence: 53%

“…For the HSLA-V and HSLA-Nb steels, the Shercliff-Ashby model provides a reasonably good description for the entire aging curves. 26) However, this is not the case for the present steel. The actual aging kinetics deviates from the predictions of the Shercliff-Ashby model significantly, i.e.…”

Section: Precipitation Strengtheningmentioning

confidence: 58%

“…Figure 13 shows examples of the recorded aging curves which are typical for precipitation strengthening in HSLA steels. 26) In the present steel, the as-cooled hardness of the torsion samples is 235 HV and reaches a peak at approximately 290 HV indicating a 55 HV precipitation strengthening contribution. The peak strength is independent of temperature and the time to peak increases with decreasing temperature.…”

Section: Precipitation Strengtheningmentioning

confidence: 65%

“…These discrepancies can be attributed to the simplified assumptions made in the model where coarsening is adopted as rate controlling mechanism. As discussed in more detail elsewhere for the 550 MPa steel and an 1.4 wt% Cu IF steel, 28) precipitate growth and the interaction of precipitation and dislocation hardening will have to be accounted for to develop a more accurate precipitation strengthening model. For industrial applications, detail of underaging and overaging behaviour is less significant.…”

Section: Precipitation Strengtheningmentioning

confidence: 99%

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Modelling of Microstructure Evolution during Hot Rolling of a 780 MPa High Strength Steel

Nakata¹,

Militzer

2005

ISIJ Int.

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The microstructure evolution during thermo-mechanical processing of a state-of-the-art Ti-Nb HSLA steel with a tensile strength of 780 MPa has been investigated with laboratory investigations. The entire hot strip rolling process was simulated with hot torsion tests. Using the Gleeble 1 500 thermomechanical simulator, constitutive behaviour, static recrystallization and austenite decompositon were quantified with single and double hit tests as well as continuous cooling transformation (CCT) tests. Precipitation strengthening was studied using aging tests. Based on the experimental results a microstructure model is proposed for hot rolling, run-out table cooling and coiling of the investigated steel. The model has been applied to predict the microstructure of industrially processed coils. The prediction of the ferrite grain size is seen to be in good agreement with that obtained during industrial hot strip rolling.

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Section: Precipitation Strengtheningsupporting

confidence: 53%

Section: Precipitation Strengtheningmentioning

confidence: 58%

Section: Precipitation Strengtheningmentioning

confidence: 65%

Section: Precipitation Strengtheningmentioning

confidence: 99%

See 2 more Smart Citations

Modelling of Microstructure Evolution during Hot Rolling of a 780 MPa High Strength Steel

Nakata¹,

Militzer

2005

ISIJ Int.

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“…31,85) However, some limitations of this rather simplified methodology have been noted for a 0.14wt%Ti-0.05wt%Nb steel 44) and for precipitation hardening by Cu. 87) In these cases, the complexity of nucleation, growth and coarsening of the precipitates has to be considered in more detail and a single parameter formulation, e.g. with P, may then be of limited use.…”

mentioning

confidence: 99%

Computer Simulation of Microstructure Evolution in Low Carbon Sheet Steels

Militzer

2007

ISIJ Int.

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Models of microstructure evolution in steels are reviewed. The emphasis of the review is on low carbon sheet steels both hot-rolled and cold-rolled and annealed. First the state-of-the-art on industrial microstructure process models is presented. The individual model concepts for grain growth, recrystallization, precipitation and phase transformations are briefly discussed. The development from empirically-based models to physically-based models is identified as a key issue to have increased predictive capabilities for these models over a wider range of steel grades and operational conditions. The challenges in the development of the next generation of models are delineated. In particular, new aspects of microstructure evolution associated with novel processing routes and advanced high strength steels are evaluated. Further, the majority of the currently employed models are on the macro-scale but future microstructure models will increasingly be meso-scale models that predict actual microstructures rather than a number of average parameters (e.g. grain size, fraction transformed) to describe microstructure evolution.KEY WORDS: mathematical model; microstructure; steel; hot rolling; annealing; grain growth; recrystallization; precipitation; phase transformation. © 2007 ISIJ Reviewvates the development of advanced microstructure models that provide an increased insight into the underlying physical metallurgy principles. Further, AHSS are frequently produced as cold-rolled annealed and/or coated sheets. Here, the intercritical annealing step assumes a crucial role to obtain the desired complex, multi-phase microstructures. Intercritical annealing constitutes a paradigm shift from annealing of conventional steels where no cycling through the transformation region occurs. The added complexity of the annealing routes for AHSS requires the development of novel annealing models that also address austenite formation which has received comparatively little attention in process models.Currently available microstructure models for the production of sheet and other steels are usually formulated on the macro-scale, i.e. the microstructure is described with a number of so-called internal state variables such as grain size, fraction recrystallized and fraction transformed. However, the advances in computer technology make it now feasible to routinely conduct modelling of the microstructure on the meso-scale if not on the atomistic level. In particular the meso-scale approach appears to open a new era of modelling the microstructure evolution in sheet steels. In this methodology actual microstructures can be predicted rather than mean values which have traditionally been used to characterize microstructures. The significance of these new modelling strategies is also fueled by the realization that material properties may markedly depend on morphology and spatial distributions of microstructure constituents. [22][23][24] In this paper, first the models proposed for hot strip rolling are reviewed. Special attention is given to the ...

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Effect of Hot‐Deformation Processes on Phase Transformation of Low‐Alloyed, Multiphase, High‐Strength Steel

Yan

Wang

et al. 2020

steel research int.

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Low‐alloyed, multiphase, high‐strength steels are strong and tough with good weldabilities and high cost‐to‐performance ratios. They have long‐term research value and broad application prospects. However, there are many types of phase transformations and complicated transformation processes that occur in these steels, which must be studied in detail. Understanding the phase transformations and their relationships to the mechanical properties of steels can theoretically facilitate material property enhancement and support the application and production of such steels. Herein, a Gleeble‐3800 thermosimulation test system is used to simulate the rolling process with different hot‐rolling process parameters. The effects of various parameters, such as the deformation, temperature, and velocity, on the phase‐transformation process and microstructural characteristics of low‐alloyed, multiphase, high‐strength steel are studied under hot deformation and subsequent cooling. The results show that low‐alloyed, multiphase, high‐strength steels generally undergo multiple types of phase transformations in a fixed order. The conditions during hot deformation have a critical influence on the phase transformation, i.e., they change the order of the phase transformations by promoting or suppressing certain phase‐transformation types. This causes different phase‐transformation types to predominate and results in different steel microstructures.

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Precipitation hardening of HSLA steels

Cited by 18 publications

References 9 publications

Modelling of Microstructure Evolution during Hot Rolling of a 780 MPa High Strength Steel

Modelling of Microstructure Evolution during Hot Rolling of a 780 MPa High Strength Steel

Computer Simulation of Microstructure Evolution in Low Carbon Sheet Steels

Effect of Hot‐Deformation Processes on Phase Transformation of Low‐Alloyed, Multiphase, High‐Strength Steel

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