CALPHAD-based alloy design for advanced automotive steels – Part II: Compositional and microstructural modification for advanced carburizing steels

Chul, Sung; Hong, Seung‐Hyun; Kim, Myung-Yeon; Park, Jihye; Shim, Jae-Hyeok; Jung, Woo-Sang; Rath, Markus; Kozeschnik, Ernst

doi:10.1016/j.calphad.2016.04.008

Cited by 11 publications

(3 citation statements)

References 19 publications

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“…For the simulation of the stress evolution during thermomechanical treatments, the knowledge of the current microstructure is mandatory. Therefore, physically based models are utilized, which can simulate the evolution of grain sizes [36,37], nucleation and growth of precipitates, or the current dislocation density. All these models are already implemented within the thermo-kinetic software package MatCalc (http://matcalc.at).…”

Section: Physical Modeling Of Microstructure Evolutionmentioning

confidence: 99%

Integrated Physical-Constitutive Computational Framework for Plastic Deformation Modeling

Viernstein

Kozeschnik

2020

Metals

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An integrated framework for deformation modeling has been developed, which combines a physical state parameter-based formulation for microstructure evolution during plastic deformation processes with constitutive creep models of polycrystalline materials. The implementations of power law, Coble, Nabarro–Herring and Harper–Dorn creep and grain boundary sliding are described and their contributions to the entire stress response at a virtual applied strain rate are discussed. The present framework simultaneously allows calculating the plastic deformation under prescribed strain rate or constant stress, as well as stress relaxation after preceding stress or strain loading. The framework is successfully applied for the construction of deformation mechanism maps.

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Section: Physical Modeling Of Microstructure Evolutionmentioning

confidence: 99%

Integrated Physical-Constitutive Computational Framework for Plastic Deformation Modeling

Viernstein

Kozeschnik

2020

Metals

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“…However, the addition of Si above 0.5 wt.% causes problems in galvanization, welding, and casting phenomenons [ 7 ]. Cr and Si are known to regulate cementite dissolution rates and, as a result, improve fatigue properties by forming fine carbide particles [ 8 ]. The susceptibility of low-partition components in the alloy, particularly sulfur, phosphorous impurities, and niobium alloyed elements, deteriorates as the temperature range increases due to segregation [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

“…These steels have complex, multi-phase austenite (FCC), martensite, ferrite (BCC), and finely scattered carbide microstructures. Phase fractions play a critical role in the success of exceptional creep and fatigue properties, and they have been extensively studied [7][8][9]. High temperatures, pressures, corrosive environments, and neutron irradiation are all conditions that RPVs must work.…”

Section: Introduction 1backgroundmentioning

confidence: 99%

Strategies Regarding High-Temperature Applications w.r.t Strength, Toughness, and Fatigue Life for SA508 Alloy

2021

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In this work, the stabilities of secondary phases, including carbides, brittle phases, and inclusions, were simulated by computational thermodynamics. Calphad strategical optimization is preferable for all steel alloys regarding energy resource consumption during manufacturing and processing. The alloy composition has been changed to enhance the strength, hardenability, and longevity of a reactor pressure vessel (RPV) steel by computing the phase equilibrium calculations and predicting mechanical properties such as yield and tensile strengths hardness and martensitic and bainitic volume fractions. The stabilities of the pro-eutectoid carbides (cementite), inclusions, and brittle phases in SA508 steel are critical to the toughness and fatigue life related to the crack initiation and expansion of this steel. Overall, the simulations presented in this paper explain the mechanisms that can affect the fatigue resistance and toughness of steel and offer a possible solution to controlling these properties at elevated temperatures by optimizing the steel composition and heat treatment process parameters.

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Suppression of Austenite Grain Coarsening by Using Nb–Ti Microalloying in High Temperature Carburizing of a Gear Steel

Tian

Wang

et al. 2019

Adv Eng Mater

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Austenite grain coarsening behavior during pseudo‐carburizing is investigated in a 18CrNiMo7‐6 steel, Nb microalloyed, and Nb–Ti microalloyed 18CrNiMo7‐6 steels, which are designed to evaluate the effects of Nb–Ti microalloying on suppressing austenite grain growth at elevated temperatures appropriate to high temperature carburizing operations. Pseudo‐carburizing heat treatments, without carburizing atmosphere, are performed in the temperature range of 850–1150 °C for 0.5–8 h. Transmission electron microscopy (TEM) incorporated with EDS spectra is used to investigate the morphology and size distributions of precipitates in pseudo‐carburized specimens. The results show that Nb–Ti microalloying has an obvious advantage in restraining austenite grain growth and increasing the grain coarsening temperature. Even in the temperature range of 1000–1150 °C, Nb–Ti microalloyed steel produces fine and uniform grain structures. The fine grain sizes observed in Nb–Ti microalloyed steel are attributed to the pinning effect of Nb–Ti precipitates that hinder austenite grain coarsening. The key reason for the significant difference of grain growth mechanisms between the base steel and Nb–Ti microalloyed steel is because Nb–Ti microalloying changes grain growth kinetic of the base steel. The results indicate that Nb–Ti microalloying can be successfully used to suppress grain growth in gear steels for high temperature carburizing.

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CALPHAD-based alloy design for advanced automotive steels – Part II: Compositional and microstructural modification for advanced carburizing steels

Cited by 11 publications

References 19 publications

Integrated Physical-Constitutive Computational Framework for Plastic Deformation Modeling

Integrated Physical-Constitutive Computational Framework for Plastic Deformation Modeling

Strategies Regarding High-Temperature Applications w.r.t Strength, Toughness, and Fatigue Life for SA508 Alloy

Suppression of Austenite Grain Coarsening by Using Nb–Ti Microalloying in High Temperature Carburizing of a Gear Steel

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