Prior austenite grain growth in heat-affected zone of a O.5Cr-Mo-V steel

The submicrometre and nanometre particle characteristics, soluble element contents, and austenite grain growth behaviors in heat-affected zone of offshore engineering steels with 0.0002 (2Mg) and 0.0042 (42Mg) wt.% Mg during the simulated welding process were studied. With increasing the Mg content in steel from 0.0002 to 0.0042 wt.%, the submicron particles are decreased in number and size with their compositions evolved from TiN to TiN + MgO capped with Mo carbides, and the number density of small-sized nanoparticles increases and large-sized nanoparticles decreases. When the temperature is below 1250 °C, the grain growth rate of two steels is not much different due to the larger Mo solute drag effect in 2Mg and larger pinning force in 42Mg. When the temperature is 1250–1300 °C, the small-sized nanoparticles in 42Mg is more than that in 2Mg, resulting in the larger pinning force and smaller grain growth rate in 42Mg. When heated to 1300–1350 °C and soaked at 1350 °C for 300 s, since large quantities of particles smaller than the critical size (dcr) are dissolved, the grain growth rate in 2Mg is smaller than that in 42Mg due to the greater amount of the effective pinning particles and larger pinning force in 2Mg.

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Austenite grain growth, microstructure and hardness in the heat-affected zone of a 2.25 Cr-1Mo steel

Materials Science and Engineering A ◽

10.1016/0921-5093(89)90399-7 ◽

1989 ◽

Vol 108 ◽

pp. 1-8 ◽

Cited By ~ 16

Author(s):

Rosa M. Miranda ◽

M.A. Fortes

Keyword(s):

Grain Growth ◽

Heat Affected Zone ◽

Austenite Grain ◽

Austenite Grain Growth

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Microstructure and Toughness Properties of Subcritically, Intercritically and Supercritically Heat Affected Zones in X80 Microalloyed Pipeline Steel

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.383-390.5886 ◽

2011 ◽

Vol 383-390 ◽

pp. 5886-5893

Author(s):

Sadegh Moeinifar

Keyword(s):

Heat Affected Zone ◽

Prior Austenite ◽

Charpy Impact ◽

Impact Testing ◽

Peak Temperature ◽

Coarse Grained ◽

Secondary Peak ◽

Thermal Cycles ◽

Austenite Grain ◽

Prior Austenite Grain

The influence of the real and simulated thermal cycles with different secondary peak temperatures on the properties of the reheated coarse grained heat affected zone (CGHAZ) in the X80 microalloyed steel has been investigated. The four wires tandem submerged arc welding process with different heat input values was used to generate real double passes thermal cycles. The simulated thermal cycles involved heating to the first peak temperature (TP1) of 1400 °C and then reheating to different secondary peak temperatures (TP2) of 700, 800 and 900 °C with cooling rates of 3.75 and 2 °C/s. The toughness of the simulated reheated CGHAZ with different peak temperature was assessed using Charpy impact testing at 0 °C and -50 °C. It is clear that the reheated CGHAZ thermal cycles with different second peak temperatures have a significant effect on morphology of the martensite/austenite (M/A) constituent. The blocky and connected M/A constituent along the prior-austenite grain boundaries as a brittle phase for crack initiation. The Charpy impact results indicated that intercritically reheated coarse grained heat affected zone had less absorbed energy with higher transition temperature and hardness. In the same prior-austenite grain size, cycles 2 and 4 with lower cooling rate (2 °C/s) have larger size of M/A constituents. The M/A constituent size such as mean diameter and length are important factors influencing Charpy impact properties of the simulated reheated CGHAZ.

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Impact of Mo content on the microstructure– toughness relationship in the coarse-grained heat-affected zone of high-strength low-alloy steels

International Journal of Materials Research (formerly Zeitschrift fuer Metallkunde) ◽

10.1515/ijmr-2020-7842 ◽

2021 ◽

Vol 112 (2) ◽

pp. 98-107

Author(s):

Yuxin Cao ◽

Xiangliang Wan ◽

Feng Zhou ◽

Yu Shen ◽

Yu Liu ◽

...

Keyword(s):

Heat Affected Zone ◽

Prior Austenite ◽

High Strength ◽

Coarse Grained ◽

Low Alloy Steels ◽

Austenite Grain ◽

Alloy Steels ◽

Mo Content ◽

Grain Boundary Pinning ◽

Prior Austenite Grain

Abstract The present study elucidates the influence of Mo content on the microstructure – toughness relationship in the coarsegrained heat-affected zone of high-strength low-alloy steels. The low-Mo and high-Mo steels were subjected to 100 kJ cm–1 heat input welding thermal cycling. The results indicated that (Ti,Mo)-carbonitrides were formed in high-Mo steel, whereas (Ti,Nb)-carbonitrides were formed in low-Mo steel. The finer and dispersed precipitates in high-Mo steel refined the prior austenite grain in the coarse-grained heat-affected zone based on the grain boundary pinning effect. However, the smaller prior austenite grain and excessive Mo content induced the formation of an entirely bainitic microstructure in high-Mo steel. Furthermore, a higher fraction of martensite –austenite constituents was observed in high-Mo steel. These results could be responsible for the deterioration of the toughness in the coarse-grained heat-affected zone of high-Mo steel.

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