In situ observation of austenite grain growth behavior in the simulated coarse-grained heat-affected zone of Ti-microalloyed steels

• Published in: International journal of minerals, metallurgy and materials Vol. 21; no. 9; pp. 878 - 885
• Main Authors: Wan, Xiang-liang, Wu, Kai-ming, Huang, Gang, Wei, Ran, Cheng, Lin
• Format: Journal Article
• Language: English
• Published: Beijing University of Science and Technology Beijing 01.09.2014; Springer Nature B.V; The State Key Laboratory of Refractories and Metal urgy, Hubei Col aborative Innovation Center for Advanced Steels, Wuhan University of Science and Technology, Wuhan 430081, China
• Subjects: Austenite; Boundaries; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Coalescence; Coarsening; Composites; Corrosion and Coatings; Ferrite; Glass; Grain boundaries; Grain boundary migration; Grain growth; Grains; Heat affected zone; Heat treating; High strength low alloy steels; Materials Science; Metallic Materials; Natural Materials; Simulation; Steels; Surfaces and Interfaces; Thermal cycling; Thermal simulation; Thin Films; Titanium; Tribology; 原位观察; 奥氏体晶粒; 晶界迁移; 模拟; 热影响区; 生长特性; 粗粒; 钛微合金钢; coarsening; grain growth; alloy steel; heat-affected zone; titanium nitride; austenite
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-014-0984-8

The austenite grain growth behavior in a simulated coarse-grained heat-affected zone during thermal cycling was investigated via in situ observation. Austenite grains nucleated at ferrite grain boundaries and then grew in different directions through movement of grain boundaries into the ferrite phase. Subsequently, the adjacent austenite grains impinged against each other during the α→γtransformation. After the α→γ transformation, austenite grains coarsened via the coalescence of small grains and via boundary migration between grains. The growth process of austenite grains was a continuous process during heating, isothermal holding, and cooling in simulated thermal cycling. Abundant finely dispersed nanoscale TiN particles in a steel specimen containing 0.012wt% Ti effectively retarded the grain boundary migration, which resulted in refined austenite grains. When the Ti concentration in the steel was increased, the number of TiN particles de- creased and their size coarsened. The big particles were not effective in pinning the austenite grain boundary movement and resulted in coarse austenite grains.