{"title":"Tailoring multi-stage microstructural evolution and mechanical responses in advanced high-strength steels across wide quenching Temperatures: Synergistic design of martensitic/bainitic carbon partitioning","authors":"Xingli Gu , Fei Li , Fei Peng , Jing Tian , Weidong Zhang , Zhenggang Wu","doi":"10.1016/j.msea.2025.148660","DOIUrl":null,"url":null,"abstract":"<div><div>This study systematically investigates the synergistic interplay between martensitic and bainitic carbon partitioning mechanisms in advanced high-strength steels (AHSS) across a broad quenching temperature (QT) range (25–400 °C). It can be found that the bainite transformation kinetics during isothermal holding are governed by QT, showing three stage-dependent acceleration linked to defect density of constituent phases. The retained austenite (RA) fractions follow QT-dependent carbon partitioning mechanisms: limited RA (≤3 vol%) arises solely from martensitic carbon partitioning at low QTs (≤100 °C), while intermediate QTs (150–200 °C) enable synergy between martensitic and bainitic carbon partitioning, with the dominant martensitic mechanism driving a rapid increase in RA content (up to ∼12 vol%). High QTs (≥225 °C) stabilize RA (∼12 vol%) via bainitic carbon partitioning constrained by the T<sub>0</sub>-line limit. In addition, a modified constrained carbon equilibrium model was developed by integrating T<sub>0</sub>-line or WBs theory to incorporate bainite formation, enabling high-precision prediction of austenite retention across the full QT range (25–400 °C). The mechanical responses also exhibit three-stage QT dependence, dictated by the characteristics of RA and dominant phase: ultrahigh strength with low ductility in M<sub>1</sub>-dominated microstructures (QT ≤ 100 °C); excellent strength-ductility combination (UTS ∼1100 MPa, TEL ∼22 %) in intermediate QTs (150–200 °C) with microstructures incorporated RA (≤12.1 vol%) and minor bainite; and stabilize (UTS ∼1000 MPa, TEL ∼22 %) in bainite-dominated regimes (QT ≥ 225 °C) with stable phase fractions. This remarkable microstructural and mechanical consistency across QTs ≥275 °C provides unparalleled process flexibility for industrial AHSS production, eliminating stringent thermal control requirements.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"941 ","pages":"Article 148660"},"PeriodicalIF":7.0000,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Materials Science and Engineering: A","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0921509325008846","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
This study systematically investigates the synergistic interplay between martensitic and bainitic carbon partitioning mechanisms in advanced high-strength steels (AHSS) across a broad quenching temperature (QT) range (25–400 °C). It can be found that the bainite transformation kinetics during isothermal holding are governed by QT, showing three stage-dependent acceleration linked to defect density of constituent phases. The retained austenite (RA) fractions follow QT-dependent carbon partitioning mechanisms: limited RA (≤3 vol%) arises solely from martensitic carbon partitioning at low QTs (≤100 °C), while intermediate QTs (150–200 °C) enable synergy between martensitic and bainitic carbon partitioning, with the dominant martensitic mechanism driving a rapid increase in RA content (up to ∼12 vol%). High QTs (≥225 °C) stabilize RA (∼12 vol%) via bainitic carbon partitioning constrained by the T0-line limit. In addition, a modified constrained carbon equilibrium model was developed by integrating T0-line or WBs theory to incorporate bainite formation, enabling high-precision prediction of austenite retention across the full QT range (25–400 °C). The mechanical responses also exhibit three-stage QT dependence, dictated by the characteristics of RA and dominant phase: ultrahigh strength with low ductility in M1-dominated microstructures (QT ≤ 100 °C); excellent strength-ductility combination (UTS ∼1100 MPa, TEL ∼22 %) in intermediate QTs (150–200 °C) with microstructures incorporated RA (≤12.1 vol%) and minor bainite; and stabilize (UTS ∼1000 MPa, TEL ∼22 %) in bainite-dominated regimes (QT ≥ 225 °C) with stable phase fractions. This remarkable microstructural and mechanical consistency across QTs ≥275 °C provides unparalleled process flexibility for industrial AHSS production, eliminating stringent thermal control requirements.
期刊介绍:
Materials Science and Engineering A provides an international medium for the publication of theoretical and experimental studies related to the load-bearing capacity of materials as influenced by their basic properties, processing history, microstructure and operating environment. Appropriate submissions to Materials Science and Engineering A should include scientific and/or engineering factors which affect the microstructure - strength relationships of materials and report the changes to mechanical behavior.