Interaction Study of Carbide Precipitation and Impurity Segregation under Temper Embrittlement Conditions in a Coarse-Grained Heat-Affected Zone in Q690 Steel

2014 ◽  
Vol 1015 ◽  
pp. 189-193 ◽  
Author(s):  
Zhen Shun Li ◽  
Sheng Li Li ◽  
Xiang Hai Zhang ◽  
Ji Zhi Liu
Keyword(s):  
Grain Boundaries ◽  
Heat Affected Zone ◽  
Temper Embrittlement ◽  
High Strength ◽  
Carbide Precipitation ◽  
Coarse Grained ◽  
Hydraulic Support ◽  
Phosphorus Segregation ◽  
Impurity Segregation ◽  
Mining Face

This work studied the interaction between carbide precipitation and impurity segregation under temper embrittlement (TE) conditions in a coarse-grained heat-affected zone (CGHAZ) in Q690 steel, a low-alloy high-strength structural steel used in the hydraulic support in the fully-mechanized mining face. From the perspective of carbide precipitation, through thermodynamics calculation and analysis, it was found that the existence of cementite at the grain boundaries was preceded by impurities segregation (primarily phosphorus). The precedent phosphorus segregation thus enhances the nucleation rate of cementite at the grain boundaries by lowering the ferrite/cementite interfacial energy. Both carbide precipitation and impurity segregation at the grain boundaries reached a maximum as a result of their mutual role in the temperature range of TE.

Effect of Post-Weld Heat Treatment on Carbide Precipitation and Impact Properties of Coarse-Grained Heat-Affected Zone of Q690 Steel

2014 ◽  
Vol 989-994 ◽  
pp. 576-580 ◽  
Author(s):  
Zhen Shun Li ◽  
Sheng Li Li ◽  
Lei Tian ◽  
Xiang Hai Zhang ◽  
Ji Zhi Liu
Keyword(s):  
Heat Treatment ◽  
Grain Boundaries ◽  
Heat Affected Zone ◽  
Unit Area ◽  
Carbide Precipitation ◽  
Post Weld Heat Treatment ◽  
Coarse Grained ◽  
Impact Properties ◽  
Carbide Particles ◽  
Weld Heat

The effect of post-weld heat treatment (PWHT) on carbide precipitation and impact properties of coarse-grained heat-affected zone (CGHAZ) of Q690 Steel was studied in this paper. Carbide particles precipitated primarily at prior austenite grain boundaries and martensitic lath boundaries. When the PWHT temperature is 520–570 °C, temper embrittlement occurs. This temperature range is also where the number of carbide particles per unit area at grain boundaries reaches its maximum. The high number of particles per unit area increases the rate of crack initiation at grain boundaries under rapid loading; linking of microcracks along grain boundaries which are already weakened by impurity segregation results in TE and intergranular fracture.

Effect of Microstructure on High-Strength Low-Alloy Steel Welded Joint Toughness with Simulation of Heat-Affected Zone Coarse-Grained Area

Metallurgist ◽  
2021 ◽  
Vol 64 (9-10) ◽  
pp. 875-884
Author(s):  
K. G. Vorkachev ◽  
P. P. Stepanov ◽  
L. I. Éfron ◽  
M. M. Kantor ◽  
A. V. Chastukhin ◽  
...  
Keyword(s):  
Alloy Steel ◽  
Heat Affected Zone ◽  
Welded Joint ◽  
High Strength ◽  
Coarse Grained ◽  
Low Alloy Steel ◽  
Effect Of Microstructure

Effect of Welding Processes with High Heat Input on the Microstructure and Toughness of Coarse-Grained Heat-Affected Zone of a High-Strength High-Toughness Steel

2018 ◽  
Vol 937 ◽  
pp. 61-67
Author(s):  
Yu Jie Li ◽  
Jin Wei Lei ◽  
Xuan Wei Lei ◽  
Oleksandr Hress ◽  
Kai Ming Wu
Keyword(s):  
Low Temperature ◽  
Impact Toughness ◽  
Heat Affected Zone ◽  
Heat Input ◽  
High Strength ◽  
High Heat ◽  
Coarse Grained ◽  
Low Temperature Impact Toughness ◽  
The Impact ◽  
Welding Processes

Utilizing submerged arc welding under heat input 50 kJ/cm on 60 mm thick marine engineering structure plate F550, the effect of preheating and post welding heat treatment on the microstructure and impact toughness of coarse-grained heat-affected zone (CGHAZ) has been investigated. The original microstructure of the steel plate is tempered martensite. The yield and tensile strength is 610 and 660 MPa, respectively. The impact absorbed energy at low temperature (-60 °C) at transverse direction reaches about 230~270 J. Welding results show that the preheating at 100 °C did not have obvious influence on the microstructure and toughness; whereas the tempering at 600 °C for 2.5 h after welding could significantly reduce the amount of M-A components in the coarse-grained heat-affected zone and thus improved the low temperature impact toughness.

Analysis on Welding Performance of the WH80 Steel Used in the Hydraulic Support

2011 ◽  
Vol 225-226 ◽  
pp. 111-114
Author(s):  
Lian Min Cao ◽  
Guo Xiu Su ◽  
Qing Liang Zeng ◽  
Xing Yuan Xiao
Keyword(s):  
Heat Affected Zone ◽  
High Strength Steel ◽  
Arc Welding ◽  
High Strength ◽  
Hardness Test ◽  
Bend Test ◽  
Hydraulic Support ◽  
Good Material

This paper mainly has carried on the analysis to the welding performance of high strength steel WH80, through the stretch and the bend test of manual welding rod, arc welding, the slanting y bevel weld crack test and the highest hardness test in welding heat-affected zone. It indicates that the WH80 steel has the good welding performance and is good material for hydraulic support.

The critical influence of La content on the microstructure-toughness relationship in the simulated coarse-grained heat-affected zone of high-strength low-alloy steels

2021 ◽  
Vol 118 (2) ◽  
pp. 212
Author(s):  
Yuxin Cao ◽  
Xiangliang Wan ◽  
Feng Zhou ◽  
Hangyu Dong ◽  
Kaiming Wu ◽  
...  
Keyword(s):  
Heat Affected Zone ◽  
Acicular Ferrite ◽  
High Strength ◽  
Coarse Grained ◽  
Low Alloy Steels ◽  
Fine Grained ◽  
Welding Thermal Cycle ◽  
Alloy Steels ◽  
High Fraction ◽  
The Impact

The present study was envisaged to investigate the role of La content on the particle, microstructure and toughness in the simulated coarse-grained heat-affected zone (CGHAZ) of high-strength low-alloy steels. Three steels with La content of 0.016 wt.%, 0.046 wt.% and 0.093 wt.% were prepared and simulated in a 100 kJ/cm heat input welding thermal cycle. Subsequently, the particle and microstructure of selected specimens were characterized and the impact absorb energy was measured at −20 °C. The results indicated that the La2O2S inclusions in 0.016 wt.%-La steel were gradually modified to LaS-LaP in 0.046 wt.%-La steel and to LaP in 0.093 wt.%-La steel. A higher fraction of acicular ferrite was obtained in the simulated CGHAZ of 0.016 wt.%-La steel, since the inclusion of La2O2S was more powerful to induce the formation of acicular ferrite. Furthermore, the fraction of M-A constituents in the simulated CGHAZ increased with increasing La content. The impact toughness in the simulated CGHAZ of 0.016 wt.%-La steel was the highest, owing to the high fraction of the fine-grained acicular ferrite and low fraction of M-A constituent.

Physical Simulation for Evaluating Heat-Affected Zone Toughness of High and Ultra-High Strength Steels

2013 ◽  
Vol 762 ◽  
pp. 711-716 ◽  
Author(s):  
Risto O. Laitinen ◽  
David A. Porter ◽  
L. Pentti Karjalainen ◽  
Pasi Leiviskä ◽  
Jukka Kömi
Keyword(s):  
Heat Affected Zone ◽  
Heat Input ◽  
Physical Simulation ◽  
Energy Requirement ◽  
High Strength Steels ◽  
High Strength ◽  
Coarse Grained ◽  
Test Results ◽  
Ultra High Strength Steels ◽  
The Impact

Physical simulation of the most critical sub-zones of the heat-affected zone is a useful tool for the evaluation of the toughness of welded joints in high-strength and ultra-high-strength steels. In two high-strength offshore steels with the yield strength of 500 MPa, the coarse grained, intercritical and intercritically reheated coarse grained zones were simulated using the cooling times from 800 to 500 °C (t8/5) 5 s and 30 s. Impact and CTOD tests as well as microstructural investigations were carried out in order to evaluate the weldability of the steels without the need for expensive welding tests. The test results showed that the intercritically reheated coarse grained zone with the longer cooling time t8/5=30 s was the most critical sub-zone in the HAZ due to the M-A constituents and coarse ferritic-bainitic microstructure. In 6 mm thick ultra-high-strength steel Optim 960 QC, the coarse grained and intercritically reheated coarse grained zones were simulated using the cooling times t8/5 of 5, 10, 15 and 20s and the intercritical zone using the cooling times t8/5 of 5 and 10 s in order to select the suitable heat input for welding. The impact test results from the simulated zones fulfilled the impact energy requirement of 14 J (5x10 mm specimen) at -40 °C for the cooling times, t8/5, from 5 to 15 s, which correspond to the heat input range 0.4-0.7 kJ/mm (for a 6 mm thickness).

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