Investigation on the Weldability of a Zr-Ti Microalloyed Pipeline Steel X120

2012 ◽  
Vol 538-541 ◽  
pp. 1478-1483 ◽  
Author(s):  
Yu Qun Yin ◽  
Hong Hong Wang ◽  
Yong Kuan Yao ◽  
Li Li ◽  
Xuan Wei Lei ◽  
...  
Keyword(s):  
Impact Toughness ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Room Temperature ◽  
Pipeline Steel ◽  
Coarse Grained ◽  
Fine Grained ◽  
Cycle Simulation ◽  
Welding Thermal Cycle ◽  
Temperature Impact

Welding thermal cycle simulation with the heat input of 12~25 kJ/cm and practical welding were undertaken to investigate the weldability of a Zr-Ti microalloyed pipeline steel X120. The microstructure in the simulated coarse-grained heat-affected zone was predominantly bainite. The Vickers hardness and room temperature impact toughness of simulated coarse-grained heat-affected zone is 276~297 (HV10) and 208~225 J, respectively. These results indicated that the X120 steel had good weldability. Practical plate welding with the heat input of 21 kJ/cm also showed that the Zr-Ti microalloyed pipeline steel X120 had high yeild strength (895 MPa) and low temperature (-30°C) impact toughness (183 J, 204 J and 208 J in the fusion line, coarse-grained heat-affected zone and fine-grained heat-affected zone, respectively).

Mechanical Properties of the Heat Affected Zone of an X100 Grade Pipeline Steel

2013 ◽  
Vol 773-774 ◽  
pp. 795-802 ◽  
Author(s):  
Gui Ying Qiao ◽  
Ming Zheng ◽  
Yu Gu ◽  
Xiu Lin Han ◽  
Xu Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Pipeline Steel ◽  
Thermal Simulation ◽  
Peak Temperature ◽  
Coarse Grain ◽  
Fine Grained ◽  
Gleeble 3500

The microstructure and mechanical properties of an X100 grade pipeline steel were investigated by the thermal simulation tests performed on a Gleeble-3500 thermal simulator. The results show that the steel has excellent weldability. Even if the weld heat input gets 40 kJ mm-1, the low impact toughness energy in welding coarse grain heat affected zone (CGHAZ) is still higher than 200 J. Yet, an embrittlement zone emerges in inter-critical HAZ (ICHAZ) at the peak temperature of 750 °C, and the lowest strength appears in fine grained HAZ (FGHAZ) at the peak temperature of 950 °C. Moreover, the strength and toughness decrease with the increase of heat input.

Effect of Heat Input on Impact Toughness of Coarse-Grained Heat-Affected Zone of a Nb-Ti Microalloyed Pipeline Steel

2012 ◽  
Vol 538-541 ◽  
pp. 2026-2031 ◽  
Author(s):  
Zhou Gao ◽  
Ran Wei ◽  
Kai Ming Wu
Keyword(s):  
Impact Toughness ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Pipeline Steel ◽  
High Heat ◽  
Coarse Grained ◽  
Bainitic Microstructure ◽  
Homogenous Distribution ◽  
High Heat Input ◽  
The Impact

The effect of varying heat inputs (20, 100, 200 kJ/cm) on the microstructures and toughness of the simulated coarse-grained heat-affected zone of a Nb-Ti microalloyed pipeline steel were investigated utilizing optical and electron microscope. Results showed that the impact toughness of the coarse-grained heat-affected zone maintained a higher level at the heat input of 20 and 100 kJ/cm, whereas it dropped to a much lower level at the heat input of 200 kJ/cm. The good toughness was attributed to the grain refinement and the homogenous distribution of fine and elongated martensite/austenite constituents. The deterioration of toughness for high heat input simulated welding was mainly caused by the coarse bainitic microstructure and massive martensite/austenite constituents.

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.

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.

Region-Specified Ratcheting Behavior of API X80 Welded Joint Under Uniaxial Cyclic Loading

2016 ◽  
Author(s):  
Hongsheng Lu ◽  
Yonghe Yang ◽  
Gang Chen ◽  
Xu Chen ◽  
Xin Wang
Keyword(s):  
Weld Metal ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Welded Joint ◽  
Pipeline Steel ◽  
Coarse Grained ◽  
Strain Accumulation ◽  
Lower Strength ◽  
Fine Grained ◽  
Ratcheting Strain

Evaluation of mechanical performance of different regions can be difficult by using standard size samples due to the size limitation of weld metal and heat-affected zone (HAZ). At first, the microstructure of different regions was characterized and quantified by Scanning Electron Microscope, which indicate that the pipeline steel is a typical acicular ferrite steel. In this study the deformation behavior of different regions (base metal, weld metal and heat affected zone) in a welded joint of API X80 pipeline steel were studied by conducting uniaxial loading tests on miniature specimens with the cross section of 2×0.5mm and gauge length of 9mm. From the results of uniaxial tension in base metal and weld metal it is shown that the welding is overmatching. Compared to the base metal, the coarse grained HAZ exhibits a lower strength, while the fine grained HAZ exhibits a higher strength. Under near zero-to-tension cyclic stress loading, all regions of the welded joints exhibit progressive accumulation of plastic strain. Under the same stress level, the base metal shows the fastest ratcheting strain accumulation, which is the result of lower strength than other regions. This fact may indicate that the ratcheting behavior of the overall welded joint is highly dependence on that of base metal for the present case. But when under the same normalized stress level (σ = σ/σYS), the fine grained HAZ has the highest ratcheting strain accumulation, while the coarse grained HAZ has the lowest ratcheting strain accumulation, which reveals that the intrinsic resistance to ratcheting is yield strength dependent.

Effect of Heat Input on Toughness of Coarse-Grained Heat-Affected Zone of an Ultra Low Carbon Acicular Ferrite Steel

2012 ◽  
Vol 538-541 ◽  
pp. 2003-2008 ◽  
Author(s):  
Zheng Hai Xia ◽  
Xiang Liang Wan ◽  
Xue Li Tao ◽  
Kai Ming Wu
Keyword(s):  
Electron Microscopy ◽  
Impact Toughness ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Acicular Ferrite ◽  
High Heat ◽  
Coarse Grained ◽  
Low Carbon ◽  
Ferrite Steel ◽  
The Impact

The effect of heat input on toughness of coarse-grained heat-affected zone of an ultra low carbon acicular ferrite steel were investigated when the welding was conducted with high heat input. Microstructural observations, energy dispersive X-ray spectroscopy analyses were conducted using optical microscopy, scanning electron microscopy and transmission electron microscopy, respectively. The microstructures of coarse-grained heat-affected zone consist of predominantly bainitic microstructure and a small proportion of acicular ferrite grains. The bainitic microstructures become coarsened with increasing heat input. The impact toughness of coarse-grained heat-affected zone remained at a higher level when the heat input ranged from 42 to 55 kJ/cm. It became not stable and dropped to a lower level when the heat input increased to 110150 kJ/cm. The enhancement in impact toughness was attributable to the MnS precipitation on the pre-formed Ti oxides as well as the formation of intragranular ferrite. When specimens were welded with higher heat input, the deterioration of impact toughness was caused by the coarsening of austenite grains.

Effect of Heat Input on Microstructure and Impact Toughness of Coarse‐Grained Heat‐Affected Zone in Al–Ca and Ti–Ca Killed Steels

2020 ◽  
Vol 91 (9) ◽  
pp. 2000133
Author(s):  
Xin Wang ◽  
Ying Chen ◽  
Chao Wang ◽  
Jian Kang ◽  
Guo Yuan ◽  
...  
Keyword(s):  
Impact Toughness ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Coarse Grained

Enhanced Low-Temperature Impact Toughness of Ultra-Fine Grained SiCp/ZL108 Composites

2012 ◽  
Vol 706-709 ◽  
pp. 1793-1798 ◽  
Author(s):  
Jing Hua Jiang ◽  
Ai Bin Ma ◽  
Ying Wu ◽  
Dan Song ◽  
Sheng Hui An ◽  
...  
Keyword(s):  
Low Temperature ◽  
Impact Toughness ◽  
Room Temperature ◽  
Simultaneous Increase ◽  
Fine Grained ◽  
New Strategy ◽  
Temperature Impact ◽  
Low Temperature Impact Toughness ◽  
Boundary Modification ◽  
Strength And Ductility

A new strategy for increasing the low-temperature toughness of structural materials is in urgent need for overcoming the general rheotropic brittleness in coarse-grain state. Here, a unique phenomenon was observed that ultra-fine-grained (UFG) SiCp/ZL108 composites after severe plastic deformation (SPD) exhibit higher impact toughness at temperatures slightly lower than room temperature. The enhanced impact toughness is attributed to the simultaneous increase of strength and ductility of UFG materials at lower temperatures, related to grains or grain fragment boundary modification. This result demonstrates the advantage of fabricating UFG materials by SPD method and spurs the interest to use UFG materials in low-temperature conditions.

Abnormal toughness characteristics and fracture model in simulated welding HAZ of 5%Ni Steel

2020 ◽  
Vol 117 (4) ◽  
pp. 410
Author(s):  
Ding Min
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Impact Toughness ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Heating Time ◽  
Coarse Grained ◽  
Large Heat ◽  
Inclusion Level ◽  
Toughness Improvement

The toughness property of the coarse grained heat affected zone had become much worse since the large heat input welding was applied in HSLA for improving welding efficiency and reducing welding costs. Unlike previous investigations of the decreasing fracture toughness with heating time, the toughness of coarse grained heat affected zone increases in long heating time. Based on microstructure and mechanical properties, very remarkable impact toughness was obtained when the t8/5 was 80 s: toughness of 171 J. The toughness improvement initiates not from inclusions but directly from the microstructure of substrate. The microstructure type and inclusion level will compete to dominate the toughness of the 5% Ni steel.

Microstructure and Properties of HAZ in Low-Carbon Bainite E550 Steel during Double-Pass Welding Thermal Cycle

2018 ◽  
Vol 913 ◽  
pp. 317-323 ◽  
Author(s):  
Yun Zong ◽  
Chun Ming Liu
Keyword(s):  
Impact Toughness ◽  
Heat Affected Zone ◽  
Thermal Cycle ◽  
Coarse Grained ◽  
Granular Bainite ◽  
Low Carbon ◽  
Microstructure And Properties ◽  
Welding Thermal Cycle ◽  
Low Carbon Bainite ◽  
The Impact

Investigations on the microstructure and properties of the Coarse-Grained Heat-Affected Zone (CGHAZ) and intercritical reheated Coarse-Grained Heat-Affected Zone (ICCGHAZ) of a low-carbon bainite E550 steel were carried out using thermal simulation technology in this paper.Double-pass welding thermal cycle were performed on Gleeble-3800 thermal simulator, tempering heat treatment of the critical coarse crystal zone carried out in a box resistance furnace, low impact energies at -40 °C and Vickers hardness determined, and the microstructure were observed. The experimental results show that the microstructure of CGHAZ (Tp1 is 1320 °C) was dominated by coarse granular bainite and Lath bainite Ferrite, the impact toughness of CGHAZ was poor. The toughness of the CGHAZ was improved after second welding heat cycle except intercritical two-phase heating. When the peak temperature of the second thermal cycle(Tp2) was 650 °C, martensite-austenite (M-A) constituent of original CGHAZ wasdecomposed and refined, impact toughness and hardness were all higher than that of CGHAZ; When Tp2 is 750 °C, there was a ” necklace” distribution of massive M-A constituent in this ICCGHAZ, the impact energy at -40 °C prominently decreased and Hardness went up; When Tp2 was in the temperature range of 850 °C ~1100 °C, the microstructure was mainly finer granular bainite, the toughness of CGHAZ could be effectively improved; When Tp2 was over 1100 °C, M-A constituents become coarse, the toughness declined slightly . The changing of hardness was the opposite of toughness but the hardness fluctuation was comparatively small. After tempering at different temperature (520 °C~640 °C) , the grain boundary "necklace" structure of ICCGHAZ was still obvious, some of the M-A constituent were decomposed, the hardness decreased, the lowest hardness was obtained in 610 °C.

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