scholarly journals Effect of Reversed Austenite on Mechanical Properties of ZG06Cr13Ni4Mo Repair Welded Joint

Coatings ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
Yunhai Su ◽  
Zuyong Wei ◽  
Gang Li ◽  
Xiangwen Zhang ◽  
Hedi Ci ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Base Metal ◽  
Welded Joints ◽  
Welded Joint ◽  
Lath Martensite ◽  
Optical Microscope ◽  
Reversed Austenite ◽  
Repair Welding ◽  
Gas Tungsten Arc

In this work, gas tungsten arc welding (GTAW) was used to repair ZG06Cr13Ni4Mo martensitic stainless steel. Repair welding occurred either once or twice. The changes in the microstructure and properties of the repair welded joints were characterized by optical microscope (OM), scanning electron microscope (SEM), electron backscattering diffraction (EBSD), tensile and impact tests. The effects of reversed austenite in repair welded joints on microstructure and mechanical properties were studied. The results show that the microstructure of the welded joint after repair welding consists of a large amount of martensite (M) and a small amount of reversed austenite (A), and the reversed austenite is distributed at the boundary of martensite lath in fine strips. With the increase in the number of welding repairs, the content of reversed austenite in the welded joint increases. The microstructure in the repair welded joints is gradually refined, the microstructure in the once and twice repaired joints is 45.2% and 65.1% finer than that in the casting base metal, respectively. The reversed austenite presented in the repair welded joints decreases the tensile strength by 4.8% and 6.7%, increases the yield strength by 21.3% and 26.4%, and increases the elongation by 25% and 56%, respectively, compared with the casting base metal. In addition, the reversed austenite mainly nucleates and grows at the boundary of lath martensite. The refinement of the martensite structure was due to the generation of reversed austenite and the refinement of original austenite grain by the welding thermal cycle. After repair welding, the reverse austenite appeared in the repair welded joints and the tensile strength decreased slightly, but the plastic toughness was significantly improved, which was conducive to the subsequent service process.

Microstructures and Mechanical Properties of Welded Joints of Several High Tensile Strength Steel

2018 ◽  
Vol 941 ◽  
pp. 224-229
Author(s):  
Takahiro Izumi ◽  
Tatsuya Kobayashi ◽  
Ikuo Shohji ◽  
Hiroaki Miyanaga
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Weld Metal ◽  
Welded Joints ◽  
Welded Joint ◽  
Steel Plates ◽  
Fatigue Properties ◽  
High Tensile Strength ◽  
The Matrix ◽  
Microstructures And Mechanical Properties

Microstructures and mechanical properties of lap fillet welded joints of several high and ultra-high tensile strength steel by arc welding were investigated. Steel plates having tensile strength of 400 (SPH400W), 590 (SPC590Y, SPC590R), 980 (SPC980Y) and 1500 MPa (SAC1500HP) class with 2 mm thickness were prepared. Four types of joints were formed by MAG welding; SPH400W/SPH400W, SPC590Y/SPC590Y, SPC980Y/SPC980Y and SAC1500HP/SPC590R. In joints with SPC590Y, SPC980Y and SAC1500HP steel which matrixes are martensitic microstructures, the HAZ softens due to transformation of martensite into ferrite with precipitating cementite. By using high and ultra-high tensile strength steel, the weld metal is strengthened due to dilution of the matrix into the weld metal and thus tensile shear strength of the welded joint increases. In the fatigue test, similar S-N diagrams were obtained in the all welded joints investigated. It seems that the effect of stress concentration due to the shape of the welded joint on fatigue properties is larger than that of the strength of the matrix.

Tensile Strength of Forged Ti-6Al-4V Welded Joints by Electronic Beam Welding

2011 ◽  
Vol 255-260 ◽  
pp. 132-136
Author(s):  
Hong Yu Qi ◽  
Jian Xie ◽  
Dong Pan ◽  
Shao Lin Li ◽  
Xiao Guang Yang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Base Metal ◽  
Welded Joints ◽  
Empirical Relationship ◽  
Weld Zone ◽  
Structure Design ◽  
Microstructure And Mechanical Properties ◽  
Welded Structure ◽  
Static Tensile

Forged Ti-6Al-4V welded structure by electronic beam welding (EBW) as integrally bladed disk (blisk) structure in advanced aero-engine has been widely applied. It is necessary to analyze microstructure and mechanical properties of Ti-6Al-4V welded joints by EBW for failure analysis and structure design of blisk. Firstly the microstructure and mechanical properties of forged Ti-6Al-4V welded joints was focused on. Grains in the weld zone become coarse and large gradient organization structure appears in the heat affected zone (HAZ), which presents significant local heterogeneity. Microhardness of the weld zone is about 20% higher than that of the base metal. The size of different region of the welded joints was estimated. Then static tensile test of three different specimens were carried on. Experiment results show that the tensile and yield strength of welded joints are not less than that of the base metal. Finally the empirical relationship between strength and hardness of Ti-6Al-4V alloy is established. Tensile strength of the weld zone and the base metal were estimated. Compared to experiment data, the deviation is 3.56%, 0.097% respectively.

scholarly journals Underwater Local Cavity Welding of S460N Steel

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5535
Author(s):  
Jacek Tomków ◽  
Anna Janeczek ◽  
Grzegorz Rogalski ◽  
Adrian Wolski
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Standard Deviation ◽  
Welded Joints ◽  
Welded Joint ◽  
Gas Metal Arc Welding ◽  
High Strength ◽  
Carbon Equivalent ◽  
High Porosity ◽  
Weld Porosity

In this paper, a comparison of the mechanical properties of high-strength low-alloy S460N steel welded joints is presented. The welded joints were made by the gas metal arc welding (GMAW) process in the air environment and water, by the local cavity welding method. Welded joints were tested following the EN ISO 15614-1:2017 standard. After welding, the non-destructive—visual, penetrant, radiographic, and ultrasonic (phased array) tests were performed. In the next step, the destructive tests, as static tensile-, bending-, impact- metallographic (macroscopic and microscopic) tests, and Vickers HV10 measurements were made. The influence of weld porosity on the mechanical properties of the tested joints was also assessed. The performed tests showed that the tensile strength of the joints manufactured in water (567 MPa) could be similar to the air welded joint (570 MPa). The standard deviations from the measurements were—47 MPa in water and 33 MPa in the air. However, it was also stated that in the case of a complex state of stress, for example, bending, torsional and tensile stresses, the welding imperfections (e.g., pores) significantly decrease the properties of the welded joint. In areas characterized by porosity the tensile strength decreased to 503 MPa. Significant differences were observed for bending tests. During the bending of the underwater welded joint, a smaller bending angle broke the specimen than was the case during the air welded joint bending. Also, the toughness and hardness of joints obtained in both environments were different. The minimum toughness for specimens welded in water was 49 J (in the area characterized by high porosity) and in the air it was 125 J (with a standard deviation of 23 J). The hardness in the heat-affected zone (HAZ) for the underwater joint in the non-tempered area was above 400 HV10 (with a standard deviation of 37 HV10) and for the air joint below 300 HV10 (with a standard deviation of 17 HV10). The performed investigations showed the behavior of S460N steel, which is characterized by a high value of carbon equivalent (CeIIW) 0.464%, during local cavity welding.

scholarly journals Effect of Preheating Temperature on Microstructure and Properties of 42CrMo4/38MnVS6 Heterogeneous Laser Welded Joint

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 870
Author(s):  
Jinlong Su ◽  
Xiaoming Qiu ◽  
Fei Xing ◽  
Ye Ruan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Welded Joint ◽  
Lath Martensite ◽  
High Hardness ◽  
Absorption Capacity ◽  
New Era ◽  
Laser Absorption ◽  
Preheating Temperature ◽  
Heavy Truck

Laser-welded forged steel pistons can meet the needs of the new era of heavy truck engines. 42CrMo4 and 38MnVS6 are widely used as piston materials due to the good mechanical properties. This study investigates the influence of preheating on microstructure and mechanical properties of 42CrMo4/38MnVS6 laser welding joint. The experimental results show preheating increases the laser absorption capacity of the metal, which can lead to an increase in weld width. The microstructure of weld is the high-hardness and poor toughness twin martensite without preheating. As the temperature of preheating increases, the twin martensite in the weld begins to transform into lath martensite and regenerates ferrite and bainite. As the preheating temperature increases, the plane fracture toughness (K1C) of the weld increases and then decreases, reaching the highest value of 2322.94 MPa·mm−1/2 at 150 °C. Compared with no preheating conditions, the tensile strength of the welded joint after preheating is improved. The fracture mode of welded joints changes from brittle fracture to ductile fracture. When the preheating temperature is 100–200 °C, the tensile strength of the welded joint reaches 1018.1–1032.5 MPa; when the preheating temperature is 250 °C–300 °C, the tensile strength decreases.

scholarly journals The Effect of Laser Offset Welding on Microstructure and Mechanical Properties of 301L to TA2 with and without Cu Intermediate Layer

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1138 ◽  
Author(s):  
Xiaohui Zhao ◽  
Zhenfu Shi ◽  
Chao Deng ◽  
Yu Liu ◽  
Xin Li
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Brittle Fracture ◽  
Welded Joints ◽  
Intermediate Layer ◽  
Welded Joint ◽  
Eutectic Reaction ◽  
Dissimilar Materials ◽  
Microstructural Characterization ◽  
The Other

Based on dissimilar materials of 301L/TA2, the effect of laser offset and copper intermediate layer on welded joints was investigated. First, the process optimization of laser offsets indicated that the tensile strength of welded joint without intermediate layer was reached to the highest value when the laser was applied on the TA2 side. On the other hand, the tensile strength of welded joint with intermediate layer performed well when laser was applied in the middle position. Then, microstructural characterization and mechanical properties of welded joints were observed and tested. Based on eutectic reaction and peritectic reaction: TiFe and TiFe2 compounds were produced for welded joint without intermediate layer. Cu-Fe solid solutions and Cu-Ti compounds were generated when copper was used as the intermediate layer. The maximum tensile strength of welded joint with and without copper intermediate layer were 396 and 193 MPa, respectively. Finally, fracture mechanism of 301L/TA2 welded joint was studied: Fe-Ti compounds caused brittle fracture of welded joints without intermediate layer; brittle fracture took place in rich copper and Cu-Ti compounds area of welded joints with copper intermediate layer.

Assessment of Welded Joints Structure Defectiveness Based on the Presence of Non-Metallic Inclusions

2017 ◽  
Vol 265 ◽  
pp. 65-69
Author(s):  
E.V. Poyarkova ◽  
I.R. Kuzeev ◽  
K.L. Zabelin
Keyword(s):  
Mechanical Properties ◽  
Base Metal ◽  
Welded Joints ◽  
Welded Joint ◽  
Complex Composition ◽  
Metallic Inclusions ◽  
Scale Levels ◽  
Spatial Geometry ◽  
Welding Joints ◽  
Structural Scale

Both welded joints and base metal are arranged at different structural-scale levels. Unlike the base metal, welded joint can have structural inclusions of complex composition and spatial geometry. During simulation and forecasting of behavior of various characteristics and properties, welded joints quality assessment is not possible without performance of corresponding metallographic studies. The article discusses the non-metallic inclusions in the oxide and silicate types welding joints and their influence on the formation of the metal mechanical properties.

The Effect of Welding Materials on 1Cr18Ni9Ti and 2Cr13 Steel Welding Joints Fracture Microstructure Pattern

2014 ◽  
Vol 881-883 ◽  
pp. 1464-1468
Author(s):  
Shao Hui Zhang ◽  
Yong Tao Zhao ◽  
Jun Wei Zhou
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Welded Joints ◽  
Lath Martensite ◽  
Residual Austenite ◽  
Welding Wire ◽  
Columnar Crystal ◽  
Welding Joints ◽  
Better Than ◽  
Welding Materials

By method of TIG, two kinds of welding materials were filled in, under certain welding craft conditions，1Cr18Ni9Ti and 2Cr13 were welded. By OM(ZEISS)、SEM，the microstructure of two kinds of 2Cr13 and 1Cr18Ni9Ti welding joints were observed and analyzed, by electronic universal tensile machine，mechanical properties of welding joints were measured. The results show that 2Cr13 and 1Cr18Ni9Ti welded joints is typical columnar crystal, the microstructure is lath martensite +residual austenite + carbide，the welding joints filled in two kinds of materials， rupture forms are toughness rupture; Elongation and tensile strength of welding joint filled in 308 welding material is better than that filled in H1Cr21Ni10Mn7Mo welding wire.

Microstructure and mechanical properties of 9Cr-3W-3Co steel welded joints by vacuum electron beam welding

2021 ◽  
pp. 2150192
Author(s):  
Youyi Zhang ◽  
Guoqing Gou
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
High Temperature ◽  
Base Metal ◽  
Welded Joints ◽  
Electron Beam Welding ◽  
Lath Martensite ◽  
Weld Zone ◽  
Creep Fracture ◽  
Welding Joints

This paper aims to explore the microstructure and mechanical properties of 9Cr-3W-3Co steel welded joints. In the experiment, 9Cr-3W-3Co steel samples were welded by vacuum electron beam welding technology (VEBW) without any metal stuff, and all the welding joints were treated by high-temperature tempering at [Formula: see text]C for 8 h. The microstructure of welding joints was observed by OM, SEM and TEM; and the mechanical properties of welded joints were analyzed by microhardness test, room-temperature tensile, test impact test and high-temperature creep test. As a result, all the 9Cr-3W-3Co steel samples displayed the microstructure status as martensite under the Scheffler-Schneider prediction model, which conformed to the expectation. After high-temperature tempering, the grains of the welding zone were smaller than the base metal and the composition was tempered lath martensite only. Some of the lath martensite bundles even showed the incomplete polygonal transformation. The M[Formula: see text]C6 carbides and MX phase were distributed continuously along with the lath martensite interfaces, which showed a tendency for further aggregation. The microhardness of the weld zone was slightly higher than the base metal (mean of base metal: 240 HV[Formula: see text], mean of weld zone: 273 HV[Formula: see text] and mean of heat affected area: 274 HV[Formula: see text]. There was no softening phenomenon observed, and the welding joints maintaining the high intensity. Other mechanical properties like the tensile strength (mean: 750 MPa), yield strength (mean: 707 MPa) and impact toughness (mean of WM: 25.1 J and HAZ: 23.3 J) were also excellent. When the temperature parameter is constant, the time for creep fracture reduces significantly with the increase of the stress; whereas the time for creep fracture decreases significantly as the temperature increases, while the stress parameter is constant.

scholarly journals The Ultimate Load Estimation of Welded Joints of High-Strength Steels subject to Mechanical and Geometric Heterogeneity

2020 ◽  
pp. 99-108
Author(s):  
S B Sapozhnikov ◽  
M A Ivanov ◽  
I A Shcherbakov
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Base Metal ◽  
Welded Joints ◽  
Stress Concentrator ◽  
Ultimate Load ◽  
Welded Joint ◽  
High Strength Steels ◽  
High Strength ◽  
Welding Wire

In this paper we consider the problems arising in the numerical estimation of the ultimate load of welded joints of high-strength steels with slight hardening. The stress concentrator in the transition node from the deposited to the base metal is modeled based on the example of welding a roller wire on a plate made of high-strength steel. The use of welding wire with a yield point lower than that of the base metal allowed to simulate areas of the welded joint with heterogeneous mechanical properties. The geometry of three areas of the welded joint is studied, i.e. weld metal, heat-affected zone (HAZ) and the base metal. Mechanical properties of all three areas are determined by calculation and experimentally. For this purpose, it is proposed to consider the material in all sections as ideally elastic-plastic, and the yield strength is uniquely associated with the hardness in the indentation zone (a Rockwell diamond cone is used). Calculations of the inelastic indentation process by the finite element method (FEM) in axis-symmetric formulation allowed obtaining a linear relationship between the hardness and the yield strength with a coefficient of 0.418. Tests at a quasi-static three-point bend (with stretching in the surfacing area) were carried out on sample beams cut perpendicular to the direction of welding. The “force-deflection” diagrams are obtained and compared with the calculated curves (FEM in a three-dimensional formulation with an explicit consideration of the complex configuration of all sections and different yield stress in the areas determined by local hardness values). There is a good agreement between the calculated and experimental ultimate loads. The proposed method of the three-stage study (determination of local hardness, yield strength in the areas and the ultimate load) can be effectively used to assess the ultimate loads of the welded joints due to the low parametricity of the proposed models of materials inelastic deformation in areas for which it is impossible to manufacture standard samples for the study of mechanical properties. The experimental study of the strengthening effect of the seam with a stress concentrator in the form of an angle of 90 degrees on the value of the ultimate bending load showed that the removal of the deposited metal does not lead to an increase in the ultimate load of the welded joint when using the welding wire of low-carbon high-plastic steel.

scholarly journals Influence of Welding Speeds on the Morphology, Mechanical Properties, and Microstructure of 2205 DSS Welded Joint by K-TIG Welding

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3426
Author(s):  
Shuwan Cui ◽  
Shuwen Pang ◽  
Dangqing Pang ◽  
Zhiqing Zhang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Grain Boundary ◽  
Welding Speed ◽  
Welded Joints ◽  
Welded Joint ◽  
Tig Welding ◽  
Phase Ratio ◽  
Boundary Misorientation ◽  
Two Phase

In this paper, 8.0 mm thickness 2205 duplex stainless steel (DSS) workpieces were welded with a keyhole tungsten inert gas (K-TIG) welding system under different welding speeds. After welding, the morphologies of the welds under different welding speed conditions were compared and analyzed. The microstructure, two-phase ratio of austenite/ferrite, and grain boundary characteristics of the welded joints were studied, and the microhardness and tensile properties of the welded joints were tested. The results show that the welding speed has a significant effect on the weld morphology, the two-phase ratio, grain boundary misorientation angle (GBMA), and mechanical properties of the welded joint. When the welding speed increased from 280 mm/min to 340 mm/min, the austenite content and the two-phase ratio in the weld metal zone (WMZ) decreased. However, the ferrite content in the WMZ increased. The proportion of the Σ3 coincident site lattice grain boundary (CSLGB) decreased as the welding speed increased, which has no significant effect on the tensile strength of welded joints. The microhardness of the WMZ and the tensile strength of the welded joint gradually increased when the welding speed was 280–340 mm/min. The 2205 DSS K-TIG welded joints have good plasticity.

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