Effects of Ti–Mg Complex Inclusions on Acicular Ferrite Nucleation

2017 ◽  
Vol 36 (5) ◽  
pp. 459-465 ◽  
Author(s):  
Kong Hui ◽  
Lin Hao ◽  
Yue Qiang ◽  
Cai Zhengyu
Keyword(s):  
Acicular Ferrite ◽  
Inclusion Size ◽  
Steel Matrix ◽  
Nucleation Effect ◽  
Treated Steel ◽  
Treated Sample ◽  
Intragranular Acicular Ferrite ◽  
Carbon Structural Steel ◽  
Ferrite Nucleation ◽  
Line Analysis

AbstractThe alloys of Ti and Mg are added in molten carbon structural steel in sequence to reveal their influence on features of inclusion and microstructure. Compared with non-treated steel, it is found that they leads to the formation of Ti-Mg-O inclusion and reduction in portion of pure MnS. Experimental results indicate that average inclusion size in treated steel significantly decreases and its number per unit volume increases by 48 %. Moreover, the margin mole ratio of Mg/Ti in all Ti-Mg-O inclusions is larger than 2, which hints they are more complex than single assumption of MgTi2O4. After etching, intragranular acicular ferrite (IAF) microstructure is observed. EDS line analysis suggests that Mn-depletion zone exists in steel matrix, which is proposed to explain the IAF nucleation effect induced by Ti-Mg-O inclusions. Through comparison with only Mg-treated sample, the refinement of inclusion and increase in portion of pure MnS due to Ti adding are revealed.

scholarly journals The Mechanism of Intragranular Acicular Ferrite Nucleation Induced by Mg-Al-O Inclusions

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Kong Hui ◽  
Zhou YaHui ◽  
Lin Hao ◽  
Xia Yunjin ◽  
Li Jie ◽  
...  
Keyword(s):  
Acicular Ferrite ◽  
Energy Dispersive Spectrometer ◽  
Steel Matrix ◽  
Sem Images ◽  
Nucleation Effect ◽  
Wide Range ◽  
Intragranular Acicular Ferrite ◽  
Carbon Structural Steel ◽  
Probabilistic Nature ◽  
Ferrite Nucleation

The features of inclusion and microstructure for carbon structural steel containing Mg-Al-O inclusions were studied through the scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS). It can be seen that, in Mg-Al-O inclusions, the elements of Mn, Si, and S coexist, and their central mole ratio of Mg/Al varies in a wide range. This value for most inclusions is larger than 0.5, which suggests the formation of solid solution between MgAl2O4and MgO. After etching, the typical microstructure of intragranular acicular ferrites is observed, which is due to the nucleation effect induced by Mg-Al-O inclusions. From the SEM-EDS mapping images, it is found that the element of sulfur accumulates on the periphery of nucleation inclusion. Moreover, line EDS analysis hints that Mn-depletion zone (MDZ) exists in steel matrix, which is adjacent to the complex inclusion. Combined with the theoretical analysis, this phenomenon can be explained by the absorption of Mn due to the magnesium vacancy in MgAl2O4, and this MDZ promotes the nucleation of intragranular acicular ferrite. Through statistical analysis of SEM images for microstructure, the probabilistic nature of inducing nucleation effect is revealed. These results may be helpful to clarify the nature of oxide metallurgy.

scholarly journals The Microstructure and Property of the Heat Affected zone in C-Mn Steel Treated by Rare Earth

2019 ◽  
Vol 38 (2019) ◽  
pp. 362-369 ◽  
Author(s):  
Ming-ming Song ◽  
Yu-min Xie ◽  
Bo Song ◽  
Zheng-liang Xue ◽  
Nan Nie ◽  
...  
Keyword(s):  
Rare Earth ◽  
Impact Toughness ◽  
Heat Affected Zone ◽  
Acicular Ferrite ◽  
Steel Matrix ◽  
Impact Properties ◽  
Treated Steel ◽  
The Impact ◽  
Welding Processes ◽  
Mn Steel

AbstractThe microstructures and impact properties of the heat affected zone (HAZ) in steel treated by rare earth (RE) under different welding processes were discussed. The effect of Al on the impact properties of the HAZ in RE treated steel was analyzed. It finds that when the welding t8/5 is smaller than 111 s, the main microstructure in steels is bainite/widmanstatten. The impact toughness of the HAZ is lower than that of the steel matrix. When t8/5 is more than 250 s, the microstructure is mainly acicular ferrite (AF) in the steel treated by RE, and the impact toughness of HAZ is obviously improved. Even under the welding processing with t8/5 about 600 s in RE treated steel can still obtain a lot of AF. While in the steel killed by Al and treated by RE, the main microstructure is parallel cluster of bainite/widmanstatten, and the impact toughness of HAZ is significantly lower than that of low-Al RE treated steel. Al can deteriorate the optimizing of RE treatment on HAZ.

Nucleation of Intragranular Acicular Ferrite in the Heat Affected Zone of Ti-Bearing Hsla Steel

2010 ◽  
Vol 168-170 ◽  
pp. 837-841
Author(s):  
Li Qing Zhang ◽  
Kai Ming Wu
Keyword(s):  
Heat Affected Zone ◽  
Acicular Ferrite ◽  
Hsla Steel ◽  
High Strength ◽  
Complex Oxides ◽  
Low Alloy Steel ◽  
X Ray ◽  
Nucleation Sites ◽  
Intragranular Acicular Ferrite ◽  
Ferrite Nucleation

The nucleation of intragranular acicular ferrite in the welding heat-affected zone of Ti-bearing high strength low alloy steel was investigated by means of electron microscopy. It was found that intragranular acicular ferrite nucleation sites under different welding heat inputs (4.3kJ/mm and 10.0kJ/mm) are titanium complex oxides on which manganese (Mn) sulfides are precipitated. The complex compound is a Si and Mn-enriched oxide. Analysis of the oxide by means of enenrgy dispersive X-ray spectrum indicated that the oxide has higher absorption ability of Si than that of Mn.

Effects of Titanium Oxide Precipitates on the Acicular Ferrite Nucleation in Carbon Structural Steel

2014 ◽  
Vol 56 (2) ◽  
pp. 131-135 ◽  
Author(s):  
Kong Hui ◽  
Shen YunFu ◽  
Zhou YaHui ◽  
Yue Qiang ◽  
Tong Lianhai ◽  
...  
Keyword(s):  
Structural Steel ◽  
Titanium Oxide ◽  
Acicular Ferrite ◽  
Carbon Structural Steel ◽  
Ferrite Nucleation

scholarly journals The Relationship between MnS Precipitation and Induced Nucleation Effect of Mg-Bearing Inclusion

2018 ◽  
Vol 37 (8) ◽  
pp. 711-716 ◽  
Author(s):  
Tian Xiangshen ◽  
Zhu Longfei ◽  
Cai ZhengYu ◽  
Kong Hui
Keyword(s):  
Crystal Structure ◽  
Electron Microscope ◽  
Energy Dispersive Spectrometer ◽  
Depletion Zone ◽  
Nucleation Effect ◽  
Treated Sample ◽  
Mns Precipitation ◽  
The Relationship ◽  
Line Analysis ◽  
Scanning Electron

AbstractThe relationship between MnS precipitation and induced nucleation effect of Mg-bearing inclusion has been explored through scanning electron microscope and energy dispersive spectrometer (EDS). Results indicate that MnS prefers to precipitate on Mg-bearing inclusions. Statistical analysis suggests that MgAl2O4 and MgO may coexist in inclusion. After etching, it is found that Mg-bearing inclusions can induce the nucleation of intragranular acicular ferrites. Based on EDS line analysis and comparison with Al-Mn-Si-O inclusion in non-Mg-treated sample, this effect can be explained by Mn-depletion zone (MDZ), which is due to the vacancy property and crystal structure of MgAl2O4. In the same sample, similar induced nucleation effect and MDZ are not observed around pure MnS. This comparison implies that the formation of MDZ may be independent of MnS precipitation.

Sign in / Sign up

Export Citation Format

Share Document