Microstructure Evolution of Fine-Grained Heat-Affected Zone of Gr.92 Steel Welded Joint During Creep

2019 ◽  
Vol 50 (7) ◽  
pp. 3080-3090 ◽  
Author(s):  
Y. Liu ◽  
S. Tsukamoto ◽  
H. Hongo ◽  
F. Yin ◽  
M. Tabuchi ◽  
...  
Keyword(s):  
Microstructure Evolution ◽  
Heat Affected Zone ◽  
Welded Joint ◽  
Fine Grained

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 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

Hardness Evolution and High Temperature Mechanical Properties of Laser Welded DP980 Steel Joints

2018 ◽  
Vol 37 (6) ◽  
pp. 587-595
Author(s):  
Zhandong Wan ◽  
Wei Guo ◽  
Qiang Jia ◽  
Lang Xu ◽  
Peng Peng
Keyword(s):  
Yield Strength ◽  
Energy Absorption ◽  
Base Metal ◽  
Welded Joint ◽  
Dynamic Strain ◽  
Minor Effect ◽  
Fiber Laser Welding ◽  
Fine Grained ◽  
High Temperature Mechanical Properties ◽  
A Minor

AbstractDP980 steels were joined using fiber laser welding. The welded joint was characterized in terms of hardness distribution and tensile behavior at room temperature, 150 ℃, and 300 ℃, respectively. The fine-grained martensite in supercritical heat affected zone (HAZ) resulted in the highest hardness (428 Hv), while the tempered martensite contributed to the hardness decreasing (‒31 Hv). Both the ultimate tensile strength and yield strength of the base metal and welded joint decreased at 150 ℃, and then increased at 300 ℃ due to dynamic strain aging (DSA). The welded joint exhibited slightly higher yield strength and lower elongation at all the test temperatures compared to base metal due to the hardened fusion zone. The energy absorption reduced slightly with increasing temperature both for base metal and welded joint, and the weld posed a minor effect on the energy absorption. Deformation was one of the requirements for DSA effect. DSA enhanced the hardness of base metal (+78 Hv) and softened zone (+53 Hv). HAZ was not softened enough to become the weakest position during tensile test.

scholarly journals The influence of manual metal arc multiple repair welding of long operated waterwall on the structure and hardness of the heat affected zone of welded joints

2017 ◽  
Vol 62 (1) ◽  
pp. 327-333 ◽  
Author(s):  
J. Pikuła ◽  
M. Łomozik ◽  
T. Pfeifer
Keyword(s):  
Heat Affected Zone ◽  
Welded Joints ◽  
Arc Welding ◽  
Power Plants ◽  
Welded Joint ◽  
Weld Bead ◽  
Boiler Steel ◽  
Metallographic Examination ◽  
Metal Arc Welding ◽  
High Degree

Abstract Welded installations failures of power plants, which are often result from a high degree of wear, requires suitable repairs. In the case of cracks formed in the weld bead of waterwall, weld bead is removed and new welded joint is prepared. However, it is associated with consecutive thermal cycles, which affect properties of heat affected zone of welded joint. This study presents the influence of multiple manual metal arc welding associated with repair activities of long operated waterwall of boiler steel on properties of repair welded joints. The work contains the results of macro and microscopic metallographic examination as well as the results of hardness measurements.

Minimization of Heat-Affected Zone Size in Welded Ultra-Fine Grained Steel under Cooling by Liquid Nitrogen during Laser Welding

2007 ◽  
Vol 539-543 ◽  
pp. 4063-4068 ◽  
Author(s):  
Hideki Hamatani ◽  
Yasunobu Miyazaki ◽  
Tadayuki Otani ◽  
Shigeru Ohkita
Keyword(s):  
Laser Welding ◽  
Liquid Nitrogen ◽  
Heat Affected Zone ◽  
Laser System ◽  
Heat Removal ◽  
Plate Temperature ◽  
Fine Grained ◽  
Laser Beam Irradiation ◽  
Average Grain Size ◽  
Plume Temperature

Ultra-fine grained steel (UFGS) with an average grain size of less than 1μm has been developed and is expected to demonstrate superior properties. However, its welded heat-affected zone, HAZ, substantially affecting the strength of a welded joint, will be easily softened after welding. Therefore, minimization of UFGS’s HAZ size during laser welding was carried out using the cooling conductor liquid nitrogen. It was found that a shielding gas with adequate flow rate for the liquid nitrogen depth was used to displace nitrogen on the area of laser beam irradiation to stabilize the weld bead. Also, because YAG laser system was mainly used because it has a lower laser induced plasma or plume temperature, which results in a decreased occurrence of pit and blowhole. HAZ size minimization strongly depends on the initial plate temperature. Reduced initial plate temperature shrinks the specific heated temperature range in which softening occurs. However, due possibly to decreasing thermal conductivity under room temperature, which prevents heat removal, the benefit of reducing the initial plate temperature is limited. The optimal initial temperature to minimize the HAZ size, in the present work, was found to be 123K.

Effects of Welding Wire Composition on Microstructure and Mechanical Properties of Welded Joint in Al-Mg-Si Alloy

2022 ◽  
Vol 905 ◽  
pp. 44-50
Author(s):  
Li Wang ◽  
Ya Ya Zheng ◽  
Shi Hu Hu
Keyword(s):  
Mechanical Properties ◽  
Fusion Zone ◽  
Heat Affected Zone ◽  
Welded Joint ◽  
Weld Zone ◽  
Xrd Analysis ◽  
Metallographic Analysis ◽  
Strengthening Effect ◽  
Welding Wire ◽  
Microstructure And Mechanical Properties

The effects of welding wire composition on microstructure and mechanical properties of welded joint in Al-Mg-Si alloy were studied by electrochemical test, X-ray diffraction (XRD) analysis and metallographic analysis. The results show that the weld zone is composed of coarse columnar dendrites and fine equated grains. Recrystallized grains are observed in the fusion zone, and the microstructure in the heat affected zone is coarsened by welding heat. The hardness curve of welded joint is like W-shaped, the highest hardness point appears near the fusion zone, and the lowest hardness point is in the heat affected zone. The main second phases of welded joints are: matrix α-Al, Mg2Si, AlMnSi, elemental Si and SiO2. The addition of rare earth in welding wire can refine the grain in weld zone obviously, produce fine grain strengthening effect, and improve the electrochemical performance of weld.

scholarly journals Study on the Effect of Heat-Input on the Thickness of the Heat-Affected Zone of the SUS316L Steel Welded Joint by Numerical Simulation

2021 ◽  
Vol 31 (5) ◽  
pp. 68-74
Keyword(s):  
Numerical Simulation ◽  
Heat Affected Zone ◽  
Heat Input ◽  
Welded Joint ◽  
Plate Thickness ◽  
Great Influence ◽  
Thickness Direction ◽  
Welding Joint ◽  
Simulation Results ◽  
The Right

The thickness of the heat-affected zone (HAZ) has a great influence on the strength of the welded joint, so one of the important tasks is to control the HAZ to a small enough level, through using the suitable heat-input (qd). In this study, the authors use SYSWELD software to compute and build a relationship between the heat-input and the thickness of the heat-affected zone in the plate thickness direction to find the right heat-input for researched welding joint. The simulation results show that when welding the root pass with qd > 552 J/mm and the cap pass with 754 J/mm < qd < 1066 J/mm, the thickness of HAZ were increased with a function almost linearly.

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