FE Simulation of Cold Cracking Susceptibility in X70 Structural Steel Welded Joints

2011 ◽  
Author(s):  
Vigdis Olden ◽  
Odd Magne Akselsen
Keyword(s):  
Hydrogen Embrittlement ◽  
Yield Strength ◽  
Structural Steel ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Fe Simulation ◽  
Coarse Grained ◽  
Best Fitting ◽  
Low Sensitivity

Fracture mechanics SENT testing and FE simulation to establish hydrogen influenced cohesive parameters for X70 structural steel welded joints have been performed. Base metal and weld simulated coarse grained heat affected zone have been included in the study. The base metal did not fail at net section stresses lower than 1.29 times the yield strength and reveals low sensitivity to hydrogen embrittlement. The weld simulated coarse grained heat affected zone was prone to fracture at stresses above 64% of the yield strength, which indicates hydrogen embrittlement susceptibility. The cohesive parameters best fitting the experiments are δc = 0.3 mm and σc = 1700 MPa (3.5·σy) for the base metal and δc = 0.3 mm and σc = 2100 MPa (2.6·σy) for the coarse grained heat affected zone.

Structure and properties of the heat-affected zone of low-alloyed cold-resistant steel for arctic application

2019 ◽  
pp. 30-51 ◽  
Author(s):  
O. V. Sych ◽  
E. I. Khlusova ◽  
U. A. Pazilova ◽  
E. A. Yashina
Keyword(s):  
Yield Strength ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Heating Temperature ◽  
Resistant Steel ◽  
Structure And Properties ◽  
Before And After ◽  
Comprehensive Study

The paper presents the results of a comprehensive study of structural and properties changes in the most dangerous regions of the heat-affected zone of low-alloyed cold-resistant steel with a guaranteed yield strength of 355–390 MPa before and after the post-welding tempering, including when the heating temperature is subjected to tempering and deformation, comparing with the base metal. The simulation was performed on the dilatometer DIL 805 and the GLEEBLE 3800 complex. The results of the investigation of the structure and properties of real welded joints after welding with different linear energy (3.5 and 6 kJ/mm) are presented.

FE Simulation of Residual Welding Stresses: Aluminium and Steel Structural Components

2016 ◽  
Vol 710 ◽  
pp. 268-274 ◽  
Author(s):  
Peter Knoedel ◽  
Stefanos Gkatzogiannis ◽  
Thomas Ummenhofer
Keyword(s):  
Yield Strength ◽  
Residual Stresses ◽  
Structural Steel ◽  
Heat Affected Zone ◽  
Fe Simulation ◽  
Fatigue Behavior ◽  
Current Paper ◽  
Structural Components ◽  
Cycling Loading ◽  
Selection Of

One of the decisive criteria in the selection of material between steel and aluminium could be the welding RS (residual stresses), which play an important role for the fatigue behavior of the structures under cycling loading. In the current paper simulations in commercial FE software ANSYS were carried out, in order to calculate the welding RS field for three different materials: structural steel S355 and the aluminum grades EN AW-6060 and EN AW-5754. In the case of EN AW-6060 influence of recrystallization on the yield strength of the HAZ (heat affected zone) was taken into consideration.

scholarly journals Microstructure and Corrosion Resistance to H2S in the Welded Joints of X80 Pipeline Steel

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1325 ◽  
Author(s):  
Jian-Bao Wang ◽  
Guang-Chun Xiao ◽  
Wei Zhao ◽  
Bing-Rong Zhang ◽  
Wei-Feng Rao
Keyword(s):  
Corrosion Resistance ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Electrochemical Corrosion ◽  
Open Circuit ◽  
Coarse Grained ◽  
Granular Bainite ◽  
X80 Pipeline Steel

The microstructure and corrosion resistance in H2S environments for various zones of X80 pipeline steel submerged arc welded joints were studied. The main microstructures in the base metal (BM), welded metal (WM), coarse-grained heat-affected zone (CGHAZ), and fine-grained heat-affected zone (FGHAZ) were mainly polygonal ferrite and granular bainite; acicular ferrite with fine grains; granular bainite, ferrite, and martensite/austenite constituents, respectively. The corrosion behavior differences resulted from the microstructure gradients. The results of the micro-morphologies of the corrosion product films and the electrochemical corrosion characteristics in H2S environments, including open circuit potential and electrochemical impedance spectroscopy, showed that the order of corrosion resistance was FGHAZ > BM > WM > CGHAZ.

Development of High-Strength Steel Plates for Low-Temperature Use

1988 ◽  
Vol 110 (3) ◽  
pp. 171-176
Author(s):  
Y. Nakano ◽  
Y. Saito ◽  
K. Amano ◽  
M. Koda ◽  
Y. Sannomiya ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Yield Strength ◽  
Structural Steel ◽  
Welded Joints ◽  
High Strength Steel ◽  
Control Process ◽  
Charpy Impact ◽  
High Strength ◽  
Steel Plates

This paper describes the metallurgical approaches for producing 415MPa and 460MPa yield strength offshore structural steel plates and the mechanical properties of the steel plates and their welded joints. A thermo-mechanical control process (TMCP) was adopted to manufacture YP415MPa and YP460MPa steel plates with weldability comparable to conventional YP355MPa steel plates. The Charpy impact and CTOD tests of the steel plates and their welded joints proved to be very good.

scholarly journals Shielded Metal Arc and Thermite Welding Effect to Residual Stress, Hardness and Crack of R54-Rail Weld Joint

2020 ◽  
Vol 55 (4) ◽  
Author(s):  
Yurianto ◽  
Gunawan Dwi Haryadi ◽  
Sri Nugroho ◽  
Sulardjaka ◽  
Susilo Adi Widayanto
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Arc Welding ◽  
Welding Process ◽  
Shielded Metal Arc Welding ◽  
Metal Arc Welding ◽  
Crack Susceptibility

The heating and cooling at the end of the welding process can cause residual stresses that are permanent and remain in the welded joint. This study aims to evaluate the magnitude and direction of residual stresses on the base metal and heat-affected zone of rail joints welded by the manual shielded metal arc and thermite welding. This research supports the feasibility of welding for rail. The material used in this study is the R-54 rail type, and the procedure used two rail samples of one meter long each, welded using manual shielded metal arc welding and thermite welding. The base metal and heat-affected zone of the welded joints were scanned with neutron ray diffraction. The scan produces a spectrum pattern and reveals the direction of the residual stress along with it. We found the strain value contained in both types of welded joints by looking at the microstrain values, which we obtained using the Bragg equation. The results show that the magnitude and direction of the residual stress produced by manual shielded metal arc welding and thermite welding are not the same. Thermite welding produces lower residual stress (lower crack susceptibility) than manual shielded metal arc welding. The melt's freezing starts from the edge to the center of the weld to create random residual stresses. The residual stress results of both the manual shielded metal arc welding and thermite welding are still below the yield strength of the base metal.

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.

Evaluation of Creep Strength Reduction Factors for Welded Joints of Grade 122 Steel

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Yukio Takahashi ◽  
Masaaki Tabuchi
Keyword(s):  
Base Metal ◽  
Creep Strength ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Thermal Power ◽  
Strength Reduction ◽  
Creep Rupture ◽  
Piping System ◽  
Type Iv ◽  
Rupture Data

HCM12A (ASME Grade 122) is used for boiler components in thermal power plants because of its high creep strength. However, a type IV creep damage formed in the heat-affected zone can cause a considerable decrease in the creep strength of the weldment and a failure of large diameter piping due to this damage took place recently in a thermal power plant. In order to update the design method and develop life estimation method for this kind of piping system with axial weld, the creep rupture data of base metal and welded joints have been collected and analyzed by the Strength of High-Chromium Steel Committee in Japan. In the present paper, the creep rupture data of over 400 points for welded joint specimens of HCM12A offered from six Japanese organizations are analyzed. These data clearly indicate that the long-term creep strength of the welded joints becomes weaker than that of the base metal at above 600°C due to the type IV fracture in the fine grain heat-affected zone. After the discussions on the effects of product form, welding procedure, specimen sampling procedure, etc., on the creep strength, the master creep life equation for the welded joints is developed. The so-called region decomposition technique was adopted to fit the data in both high and low stress regimes with a reasonable accuracy. The creep strength reduction factor obtained from 100,000 h creep strength of the welded joints and the base metal is given as a function of temperature.

scholarly journals Evaluation of Hydrogen-Assisted Cracking Susceptibility in Grade T24 Steel

2020 ◽  
Vol 99 (4) ◽  
pp. 101s-109s
Author(s):  
XIULI FENG ◽  
◽  
JOSEPH M. STEINER ◽  
BOIAN T. ALEXANDROV ◽  
JOHN C. LIPPOLD
Keyword(s):  
Base Metal ◽  
Heat Affected Zone ◽  
Fracture Behavior ◽  
Coarse Grained ◽  
Internal Diameter ◽  
Microvoid Coalescence ◽  
Martensitic Microstructure ◽  
Steel Base ◽  
Hydrogen Assisted Cracking ◽  
Martensite Microstructure

The delayed hydrogen cracking test was performed to evaluate the hydrogen-assisted cracking (HAC) susceptibility of Grade T24 steel base metal and the simulated coarse-grained heat-affected zone (CGHAZ). The base metal did not fail after testing for up to 672 h. In contrast, the CGHAZ sample failed after about 2 h when charged from all four sides, and 4 h when charged only from the internal diameter (ID) surface. The higher HAC resistance of the base metal compared to the CGHAZ was due to the microstructure difference. The tempered bainitic-martensitic microstructure in the base metal was more resistant to HAC compared to the untempered martensite microstructure in the CGHAZ. Fractography analysis indicated the decarburized zone on the ID surface delayed the development of the critical hydrogen concentration in the CGHAZ, thus improving the HAC resistance. The HAC cracking initiated with an intergranular fracture, then transitioned to quasi-cleavage and microvoid coalescence. The fracture behavior was explained using Beachem’s model.

scholarly journals NIOBIUM EFFECT ON BASE METAL AND HEAT AFFECTED ZONE MICROSTRUCTURE OF GIRTH WELDED JOINTS

2017 ◽  
Vol 23 (1) ◽  
pp. 55 ◽  
Author(s):  
Andrea Di Schino ◽  
Paolo Emilio Di Nunzio
Keyword(s):  
Base Metal ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
High Strength ◽  
Industrial Scale ◽  
Niobium Content ◽  
Hsla Steels ◽  
Zone Microstructure

<p>The development of steels for line pipes during the last decades has been driven by the need to obtain improved combinations of high strength, toughness, weldability on industrial scale at affordable prices. The effect of niobium content on the heat affected zone (HAZ) microstructure is reported in this paper. Niobium, for its specific thermodynamic and kinetic attitude to form carbide and nitride precipitates, played a key role in the development of modern HSLA steels Results show that niobium addition is able to refine both the bainitic packet and cells size in the heat affected zone during welding. This implies that niobium  addition leads to an improvement of both toughness and hardness of welded joints manufactured by Nb micro-alloyed steels.</p><p> </p>

Study of wear resistance of railway rails welded joint

2020 ◽  
Vol 76 (8) ◽  
pp. 818-825
Author(s):  
N. A. Kozyrev ◽  
R. A. Shevchenko ◽  
A. A. Usol'tsev ◽  
R. E. Kryukov ◽  
A. R. Mikhno
Keyword(s):  
Wear Resistance ◽  
Thermal Treatment ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Welded Joint ◽  
Welding Method ◽  
Welded Seam ◽  
Short Time ◽  
Metal Hardness

Welding joints of rails are a weak point of a jointless railway line, which stipulates actuality of studies on increasing their operational resistance. Microstructures of welded joints made by existing at present welding technology and by a new one were compared. Existing (base) technology comprises further thermal treatment of the welded joint, while the new technology comprises welding followed by a short-time electric current impact during the rail joint cooling. To study the microstructures of welded joints, samples were cut out the welded seam zone and heat affected zone, as well as out of the base metal. The study was carried out in the depth of 5 mm from the surface, after thin section etching by 4% solution of nitric acid in alcohol. In the macro-structure of the metal of welded joint, made by the base technology, an uneven heat affected zone was detected. The zone had the following dimensions: 51 mm – in the head, from 45 mm to 62 mm – in the neck and 64 mm – in the bottom (by each of the seal side). In the longitudinal mac- ro-template of sample Б (the new welding method), the heat affected zone was even and along the whole joint had the width of 22 mm (in each of the joint side). It was shown, that the new welding method of railway rails enables to decrease the extension of zone with sorbitic and granular pearlite at various stage of coagulation. A short-time impact of electric current during rail joint cooling ensures obtaining a zone with a decreased hardness of 15 mm extension and decrease of welded seam metal hardness relatively the lower border of base metal hardness by less than 15%. Application an additional local thermal treatment by a separate induction heating during base technology results in forming zones of 30 mm extension in the area of welded joint, which wear resistance is 4.5 times lower comparing with wear resistance of the rail base metal. At the new welding method application, the extension of the abovementioned zone does not exceed 10 mm and wear resistance was decreased by less than 2 times.

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