scholarly journals The Role of Mn Depletion in Intra-Granular Ferrite Transformation in the Heat Affected Zone of Welded Joints with Large Heat Input in Structural Steels.

1996 ◽  
Vol 36 (11) ◽  
pp. 1406-1412 ◽  
Author(s):  
Hidesato Mabuchi ◽  
Ryuji Uemori ◽  
Masaaki Fujioka
Keyword(s):  
Heat Affected Zone ◽  
Welded Joints ◽  
Heat Input ◽  
Structural Steels ◽  
Ferrite Transformation ◽  
Large Heat

Effect of Nb Content on the Impact Toughness of Coarse-Grained Heat-Affected Zone of Pipeline Steels under Large Heat Input

2014 ◽  
Vol 1078 ◽  
pp. 3-7
Author(s):  
Feng Zhou ◽  
Zhou Gao ◽  
Kai Ming Wu
Keyword(s):  
Heat Affected Zone ◽  
Heat Input ◽  
Optical Microscope ◽  
Coarse Grained ◽  
Electron Backscattered Diffraction ◽  
Pipeline Steels ◽  
Nb Content ◽  
Large Heat ◽  
Austenite Grains ◽  
The Impact

The effect of large heat inputs (200 kJ/cm) on the microstructures and toughness of heat-affected zone of Nb microalloyed X70 pipeline steels were simulated utilizing Gleeble-3800. The microstructures were observed by optical microscope, scanning electron microscope and electron backscattered diffraction technique. Results showed that when the large heat input welding was applied, big austenite grains and coarse microstructures were formed in the coarse-grained heat-affected zone, and thus the toughness of the coarse-grained heat-affected zone was seriously reduced. With the increase of Nb content, the toughness of the CGHAZ did not change remarkably under the large heat input welding.

Evaluation of Influence of Thermal Methods of Metal Separation Cutting on Welding Quality

2017 ◽  
Vol 265 ◽  
pp. 755-761 ◽  
Author(s):  
A.K. Tingaev ◽  
M.A. Ivanov ◽  
A.M. Ulanov
Keyword(s):  
Heat Affected Zone ◽  
Welded Joints ◽  
Heat Input ◽  
Experimental Studies ◽  
Welding Process ◽  
Regulatory Requirements ◽  
High Quality ◽  
Thermal Methods ◽  
Welding Seam

We have investigated a possibility of obtaining high-quality welded joints after oxygen and plasma cutting of steel С355 without removing the heat-affected zone (HAZ), in which the changes in chemical, phase and structural compositions are observed. Numerical and experimental studies of the effect of heat input of MAG and Submerged Arc welding on the quality of welded joints are performed. In particular, it was found that when the heat input of welding is at least 6.5 kJ/cm, the metal of HAZ of the edges after cutting is heated during the welding to temperatures above Ас3, which leads to its full recrystallization. When the heat input of welding is at least 10 kJ/cm, the edges after cutting are completely melted and become a part of the welding seam metal. The presence of extensive areas of melting and recrystallization of the edges in the welding process contributes to obtaining high-quality welded joints without removing the HAZ of the edges after cutting. To verify the results of numerical studies, experimental tests of control welded joints were conducted, which showed that the values of bending angle and impact toughness of the welding seam metal and heat affected zone are significantly above the regulatory requirements to quality of welded joints, and not less than the same requirements for steel С355. The obtained results confirm the possibility of revising domestic regulatory requirements for the steel constructions production in terms of the preparation of edges for welding using technologies of thermal cutting without subsequent machining.

scholarly journals Evaluation of the structural stability of welded joints in welding

2021 ◽  
Vol 2131 (4) ◽  
pp. 042063
Author(s):  
V Schepkin ◽  
Yu Poletaev
Keyword(s):  
Structural Stability ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Heat Input ◽  
Thermal Conditions ◽  
Fluctuation Analysis ◽  
Power Equipment ◽  
Chemical Homogeneity ◽  
Urgent Task ◽  
The Stability

Abstract Brittle (intergranular) destruction of the heat-affected zone metal (local failure) of welded joints of power equipment during welding and heat treatment (tempering) was an unexpected and serious problem. Its solution based on the development of progressive technological solutions is an urgent task of modern power engineering. The article considers an applied method of fluctuation analysis for assessing the stability of the structure and the probability of local destruction (LD) of the metal of the heat-affected zone (HAZ) of thick-walled welded structures of power equipment made of low-alloy steel 15Kh2NMFA. A computational - experimental method for calculating the range of optimal values of heat input is stated. The LD mechanism is stated and its connection with the technology and thermal conditions of welding and the structural stability of the HAZ metal is established. It was found that the growth of austenite grains of the HAZ metal stimulates the tendency to LD, if a dendrid-type carbide phase is precipitated at grain boundaries during welding. By optimizing the heat input during welding, it is possible to control the structural and chemical homogeneity of the HAZ metal and the associated tendency to form LD.

scholarly journals Corrosion Behavior of Welded Joints in Different Stainless Steels

2001 ◽  
Vol 71 (3) ◽  
pp. 440-449
Author(s):  
Eniko Reka Fabian ◽  
Janos Kuti ◽  
Jozsef Gati ◽  
Laszlo Toth
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Pitting Corrosion ◽  
Stainless Steels ◽  
Heat Affected Zone ◽  
Welding Speed ◽  
Welded Joints ◽  
Heat Input ◽  
Laser Power ◽  
Base Material

The welded metals characteristics produced by TIG welding or laser beam welding depend on heat input as a function of laser power and welding speed. High laser power and high welding speed have produced welded joint with a remarkable decrease in fusion zone size and an acceptable weld profile with high weld depth/width ratio. At duplex stainless steels the microstructure of welded metal, and heat affected zone is strongly influenced by cooling rate, which is depend on heat input as a function of laser power and/or welding speed. It was found that increasing welding speed the corrosion rate of welded joints decreased. In austenitic stainless steels appeared pitting corrosion in the base material as well as in the welding zone. In case of 2304 duplex stainless steel pitting corrosion appeared in welded metal and heat affected zone in case of autogenously welding, but at 2404 duplex stainless steel pitting appear more in the heat affected zone.

scholarly journals Microstructure and Mechanical Properties of a Fiber Welded Socket-Joint Made of Powder Metallurgy Molybdenum Alloy

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 640 ◽  
Author(s):  
Miao-Xia Xie ◽  
Yan-Xin Li ◽  
Xiang-Tao Shang ◽  
Xue-Wu Wang ◽  
Jun-Yu Pei
Keyword(s):  
Grain Boundary ◽  
Welding Speed ◽  
Welded Joints ◽  
Heat Input ◽  
High Performance ◽  
Molybdenum Alloy ◽  
Refined Grains ◽  
Welding Heat Input ◽  
Tensile Fractures

Fiber welding of socket-joints made of nanostructured high-performance molybdenum alloy (NS Mo) was carried out to get a better understanding of the role of welding heat input. It was found that low heat input (i.e., high welding speed) resulted in significantly refined grains in the fusion zone (FZ) of fiber laser welded NS Mo joints. When welding heat input decreased from 3600 J/cm (i.e., 1.2 kW, 20 cm/min) to 250 J/cm (i.e., 2.5 kW, 600 cm/min), the tensile strength of welded joints increased from about 250 MPa to about 570 MPa. It was confirmed by energy spectrum analysis that the higher the welding heat input, the higher the oxygen contents at the grain boundary (GB) within the FZ. In addition, the most important reason for poor strength of welded joints of Mo alloys was reported as being that MoO2 was segregated on the grain boundary. Therefore, it was concluded that welding under low heat input (i.e., high welding speed) was able to reduce the segregation degree of MoO2 at the grain boundary by refining grains and increasing the total area of GBs, thus improving the strength of welded joints and reducing the proportion of the intergranular fracture zone in tensile fractures.

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