Cargando…

In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process

The relationships between initial microstructures, process parameters, and grain evolutions in isothermal holdings have drawn wide attention in recent years, but the grain growth behaviors of 300M steel were not well understood, resulting in a failure in precise microstructure controlling in heat tr...

Descripción completa

Detalles Bibliográficos
Autores principales: Chen, Rongchuang, Zheng, Zhizhen, Li, Jianjun, Li, Ning, Feng, Fei
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6213102/
https://www.ncbi.nlm.nih.gov/pubmed/30274356
http://dx.doi.org/10.3390/ma11101862
_version_ 1783367693654556672
author Chen, Rongchuang
Zheng, Zhizhen
Li, Jianjun
Li, Ning
Feng, Fei
author_facet Chen, Rongchuang
Zheng, Zhizhen
Li, Jianjun
Li, Ning
Feng, Fei
author_sort Chen, Rongchuang
collection PubMed
description The relationships between initial microstructures, process parameters, and grain evolutions in isothermal holdings have drawn wide attention in recent years, but the grain growth behaviors of 300M steel were not well understood, resulting in a failure in precise microstructure controlling in heat treatment. In this work, in situ observations were carried out to characterize the grain evolutions of 300M steel with varying holding time, holding temperatures, and initial microstructures. The intriguing finding was that the grain refinement by austenization of 300M steel was followed by a dramatic grain growth in the initial stage of holding (≤~600 s), and with increasing time (~600–7200 s), the average grain size appeared to have a limit value at specific temperatures. The austenization process accelerated the grain growth by generating large quantity of grain boundaries at the initial stage of holdings, and the growth rate gradually slowed down after holding for ~600 s because the driven force was weakened due to the reduction of grain boundary energy. The initial structure and the initial grain size of 300M steel had no obvious influences on the grain size evolutions. The mechanisms of grain growth were analyzed based on in situ observations and transmission electron microscope (TEM) characterizations. A grain evolution model considering the grain boundary migration of 300M steel was established for the isothermal holding process. Good agreement was obtained between the in situ observation results and the model calculation results. This investigation aimed to understand fundamentally the grain evolutions of 300M steel in the isothermal holding process.
format Online
Article
Text
id pubmed-6213102
institution National Center for Biotechnology Information
language English
publishDate 2018
publisher MDPI
record_format MEDLINE/PubMed
spelling pubmed-62131022018-11-14 In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process Chen, Rongchuang Zheng, Zhizhen Li, Jianjun Li, Ning Feng, Fei Materials (Basel) Article The relationships between initial microstructures, process parameters, and grain evolutions in isothermal holdings have drawn wide attention in recent years, but the grain growth behaviors of 300M steel were not well understood, resulting in a failure in precise microstructure controlling in heat treatment. In this work, in situ observations were carried out to characterize the grain evolutions of 300M steel with varying holding time, holding temperatures, and initial microstructures. The intriguing finding was that the grain refinement by austenization of 300M steel was followed by a dramatic grain growth in the initial stage of holding (≤~600 s), and with increasing time (~600–7200 s), the average grain size appeared to have a limit value at specific temperatures. The austenization process accelerated the grain growth by generating large quantity of grain boundaries at the initial stage of holdings, and the growth rate gradually slowed down after holding for ~600 s because the driven force was weakened due to the reduction of grain boundary energy. The initial structure and the initial grain size of 300M steel had no obvious influences on the grain size evolutions. The mechanisms of grain growth were analyzed based on in situ observations and transmission electron microscope (TEM) characterizations. A grain evolution model considering the grain boundary migration of 300M steel was established for the isothermal holding process. Good agreement was obtained between the in situ observation results and the model calculation results. This investigation aimed to understand fundamentally the grain evolutions of 300M steel in the isothermal holding process. MDPI 2018-09-30 /pmc/articles/PMC6213102/ /pubmed/30274356 http://dx.doi.org/10.3390/ma11101862 Text en © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Chen, Rongchuang
Zheng, Zhizhen
Li, Jianjun
Li, Ning
Feng, Fei
In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process
title In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process
title_full In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process
title_fullStr In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process
title_full_unstemmed In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process
title_short In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process
title_sort in situ investigation of grain evolution of 300m steel in isothermal holding process
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6213102/
https://www.ncbi.nlm.nih.gov/pubmed/30274356
http://dx.doi.org/10.3390/ma11101862
work_keys_str_mv AT chenrongchuang insituinvestigationofgrainevolutionof300msteelinisothermalholdingprocess
AT zhengzhizhen insituinvestigationofgrainevolutionof300msteelinisothermalholdingprocess
AT lijianjun insituinvestigationofgrainevolutionof300msteelinisothermalholdingprocess
AT lining insituinvestigationofgrainevolutionof300msteelinisothermalholdingprocess
AT fengfei insituinvestigationofgrainevolutionof300msteelinisothermalholdingprocess