Microstructure and toughness of laser welded joint of 400MPa ultra-fine grained steel

2002 ◽  
Author(s):  
Xudong Zhang ◽  
Wuzhu Chen ◽  
Cheng Wang ◽  
Yun Peng ◽  
Zhiling Tian
Keyword(s):  
Welded Joint ◽  
Fine Grained

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.

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

Mechanical Properties and Fracture Toughness of Aluminum Vessels by Friction Stir Welding

2004 ◽  
Author(s):  
Masahito Mochizuki ◽  
Masao Toyoda ◽  
Masayuki Inuzuka ◽  
Hidehito Nishida
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Crack Initiation ◽  
Base Metal ◽  
Welded Joint ◽  
Stir Zone ◽  
Crack Initiation And Propagation ◽  
Friction Stir ◽  
Fine Grained ◽  
Initiation And Propagation

Mechanical properties and fracture toughness in friction stir welded joint of vessels of structural aluminum alloy type A5083-O are investigated. Welded joint from 25 mm-thick plate is fabricated by one-side one-pass friction stir. Charpy impact energy and critical crack-tip opening displacement (CTOD) in friction stir weld are much higher than those of base metal or heat-affected zone, whereas mechanical properties such as stress-strain curve and Vickers hardness do not have a conspicuous difference. Effects of microstructure on crack initiation and propagation are studied in order to clarify the difference of fracture toughness between stir zone and base metal. Both tensile test and bending test show that the fine-grained microstructure in stir zone induces to increase ductile crack initiation and propagation resistance by analyzing fracture resistance curves and diameter of dimples in fracture surface. It is found that high fracture toughness value in stir zone is affected fine-grained microstructure by friction stirring.

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.

Testing of Welded Joints between Pipes for Pressure Vessels Made of Hot Rolled Fine-Grained Steel P460NL1

2020 ◽  
Vol 1157 ◽  
pp. 15-20
Author(s):  
Miodrag Arsić ◽  
Srđan Bošnjak ◽  
Vencislav Grabulov ◽  
Mladen Mladenović ◽  
Zoran Savić
Keyword(s):  
Tensile Properties ◽  
Welded Joints ◽  
Arc Welding ◽  
Welded Joint ◽  
Welding Process ◽  
Pressure Vessels ◽  
Parent Material ◽  
Fine Grained ◽  
Hot Rolled ◽  
Material Standard

This paper contains results of tests performed in order to determine mechanical properties of steel P460NL1, used as filler material during the execution of welded joints. Arc welding of samples from which the specimens were taken was carried out through the application of welding process 111, because it is one of the processes for the execution of pipelines for pressure equipment. Microspecimens with diameter of Ø1,5 mm were tested in order to determine tensile properties of material taken from the heat-affected zone and weld metal, while specimens with diameter of Ø6 mm were tested in order to determine tensile properties of parent material. Standard Charpy V-notch specimens were used in order to determine impact energy. Results of metallographic tests which refer to the structure of a pipe welded joint are also presented.

scholarly journals The Analysis of the Post-Operation Microstructure and Mechanical Properties of the Similar Welded Joint

2020 ◽  
pp. 37-41
Author(s):  
Agata Merda ◽  
Klaudia Klimaszewska
Keyword(s):  
Mechanical Properties ◽  
Welded Joint ◽  
Base Material ◽  
Steam Pressure ◽  
Test Material ◽  
Quality Level ◽  
Fine Grained ◽  
Post Operation ◽  
Non Destructive ◽  
M23c6 Carbides

The test material was a specimen sampled from sections of a pipe operated for 41,914 hours at a temperature of 575°C and under a steam pressure of 28.2 MPa. The specimen subjected to metallurgical tests was a welded joint made of austenitic steel TP347HFG. The non-destructive tests and the macroscopic tests confirmed the lack of any welding imperfections. The test joint represented quality level B in accordance with related standard requirements. The microstructural tests of the heat-affected zone (HAZ) revealed the presence of the fine-grained austenitic structure with numerous precipitates on grain boundaries – probably M23C6 carbides. In spite of long-lasting operation, the mechanical properties of the test welded joint were high and did not exceed the standard-related requirements concerning the base material.

A Study on the Creep Rupture Life Estimation of Internally Pressurized Welded Pipe Joints

2006 ◽  
Author(s):  
Tetsuo Teramae
Keyword(s):  
Crack Growth ◽  
Welded Joint ◽  
Rupture Life ◽  
Creep Rupture ◽  
Coarse Grained ◽  
Experimental Result ◽  
Fine Grained ◽  
Pipe Joints ◽  
Creep Rupture Test ◽  
Welded Pipe

A study had been conducted to establish the precise method estimating the creep rupture life of welded steam pipe joints used for thermal power plants. Firstly, basic creep data of 2.25CrlMo low alloy steel, such as rupture time, minimum creep strain rate, and creep crack growth rate, had been obtained on mother material, fine-grained heat affected zone (HAZ), coarse-grained HAZ, and weld metal. Secondly, internally pressurized creep rupture test had been conducted on the pipe specimens of mother material, seam welded joint and girth welded joint. Whereas girth welded pipe joints showed longer lives than those of mother material pipes, seam welded pipe joints showed shorter rupture lives. To clarify the effect of fine-grained HAZ on the rupture life of the seam welded pipe joint, an analytical study had been performed taking the difference of creep deformation between fine-grained HAZ and mother material into account. The analytical creep rupture life had agreed quite well with experimental one. Finally, internally pressurized creep rupture test had been conducted on the specimens of the seam welded pipe joints with a semi-elliptical notch introduced along the outer HAZ of weld line. Creep rupture life of these specimens was calculated as the sum of crack incubation time and crack growth time. It was shown that the calculated creep rupture life had agreed quite well with the experimental result.

scholarly journals Microstructure and Mechanical Properties of Welded Joints in Austenitic Steel TP347HFG after Operation

2020 ◽  
pp. 67-73
Author(s):  
Kwiryn Wojsyk ◽  
Agata Merda ◽  
Klaudia Klimaszewska ◽  
Paweł Urbańczyk ◽  
Grzegorz Golański
Keyword(s):  
Grain Boundaries ◽  
Welded Joint ◽  
High Hardness ◽  
Continuous Lattice ◽  
High Tensile Strength ◽  
High Impact Energy ◽  
Fine Grained ◽  
Face Area ◽  
Annealing Twins ◽  
Precipitation Processes

The analysis involved a similar welded joint made of steel TP347HFG after operation at a temperature of 580°C. Tests revealed that the primary mechanisms responsible for the degradation of the microstructure in all areas of the joint subjected to analysis were precipitation processes within the grains and along the grain boundaries. The grain boundaries contained two morphologies forming a continuous lattice. Precipitation processes resulted in the high tensile strength of the joint and high hardness within the weld face area. After operation, the test joint was characterised by relatively high impact energy, which could be attributed to the fine-grained microstructure and the presence of numerous annealing twins.

scholarly journals Investigation on the validity of creep damage mechanics for the life time prediction of T92 welded joint

2019 ◽  
Vol 29 (3) ◽  
pp. 467-481 ◽  
Author(s):  
Xiao Wang ◽  
Xue Wang ◽  
Qiang Xu ◽  
Chuang Wang ◽  
Ya-lin Zhang ◽  
...  
Keyword(s):  
Damage Mechanics ◽  
Welded Joint ◽  
Rupture Life ◽  
Continuum Damage Mechanics ◽  
Creep Process ◽  
Continuum Damage ◽  
Creep Life ◽  
Fine Grained ◽  
Creep Time ◽  
The Continuum

This paper reports the damage evolution in ASME T92 welded joints during creep process. The creep test was conducted at 650℃ with applied stress of 90 MPa. The creep specimen was ultimately fractured at the fine-grained heat affected zones after creep for 1560 h. The metallographic results show that the cavity number and size in fine-grained heat affected zones increase with the creep time. The coalescence of creep cavities happened at the late stage of the creep life, which depending on the adjacent voids grows and propagates into the micro-crack. Besides, the deterioration in fine-grained heat affected zones of T92 steel welded joint with various creep time can be simulated based on the continuum damage mechanics with modified Kachanov-Rabotnov constitutive equation. The result of simulated creep rupture life is in good agreement with the experimental value, which indicates that the continuum damage mechanics can be used to predict creep life and evaluate creep deterioration in a T92 steel welded joint.

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