scholarly journals Influence of Surface Ultrasonic Rolling on Microstructure and Corrosion Property of T4003 Ferritic Stainless Steel Welded Joint

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1081 ◽  
Author(s):  
Pengtao Liu ◽  
Runze Yu ◽  
Xinhuan Gao ◽  
Guanzhen Zhang
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Corrosion Resistance ◽  
Fatigue Life ◽  
Welded Joints ◽  
Welded Joint ◽  
Weld Zone ◽  
Surface Hardness ◽  
Joint Surface ◽  
Deformation Layer

In this paper, the effect of surface ultrasonic rolling treatment (SURT) on surface properties of T4003 cold metal transfer (CMT) welded joints was studied. Surface topography and microstructure changes of the welded joint surface before and after SURT were observed by optical microscope and scanning electron microscope. The hardness and residual stress distribution of welded joint were measured by a microhardness tester and X-ray diffractometer. The change of corrosion resistance of welded joints was studied by electrochemical polarization curve measurement. The results show that surface roughness (Ra) of the weld zone, heat affect zone (HAZ), and base metal after SURT was reduced to 0.320 μm, 0.156 μm, and 0.227 μm, respectively, and surface morphology became smooth. The plastic deformation layer and working hardening layer were formed at the welded joint. The degree of plastic deformation of the weld zone was more serious than that in the base metal, and grains in weld zone was obviously refined. The thickness of plastic deformation layer was about 100 μm. The surface hardness in the weld zone was highest, which is about 420 HV. The refinement of grains and the increase of surface hardness can improve the fatigue life of welded joint. After SURT, the residual stress in the welded joint changes from residual tensile stress to residual compressive stress, which can also improve fatigue life of the welded joint. Surface corrosion resistance of welded joints after SURT was improved due to smooth surface and the formation of fine grains layer.

scholarly journals Improving the Properties of Laser-Welded Al–Zn–Mg–Cu Alloy Joints by Aging and Double-Sided Ultrasonic Impact Compound Treatment

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2742
Author(s):  
Furong Chen ◽  
Chenghao Liu
Keyword(s):  
Plastic Deformation ◽  
Tensile Strength ◽  
Tensile Properties ◽  
Welded Joints ◽  
Welded Joint ◽  
Weld Zone ◽  
Aging Treatment ◽  
Residual Tensile Stress ◽  
Impact Surface ◽  
Deformation Layer

To improve the loose structure and serious porosity of (Al–Zn–Mg–Cu) 7075 aluminum alloy laser-welded joints, aging treatment, double-sided ultrasonic impact treatment (DSUIT), and a combination of aging and DSUIT (A–DSUIT) were used to treat joints. In this experiment, the mechanism of A–DSUIT on the microstructure and properties of welded joints was analyzed. The microstructure of the welded joints was observed using optical microscopy, scanning electron microscopy, and electron backscatter diffraction (EBSD). The hardness and tensile properties of the welded components under the different processes were examined via Vickers hardness test and a universal tensile testing machine. The results showed that, after the aging treatment, the dendritic structure of the welded joints transformed into an equiaxed crystal structure. Moreover, the residual tensile stress generated in the welding process was weakened, and the hardness and tensile strength were significantly improved. After DSUIT, a plastic deformation layer of a certain thickness was generated from the surface downward, and the residual compressive stress was introduced to a certain depth of the joint. However, the weld zone unaffected by DSUIT still exhibited residual tensile stress. The inner microhardness of the joint surface improved; the impact surface hardness was the largest and gradually decreased inward to the weld zone base metal hardness, with a small improvement in the tensile strength. Compared with the single treatment process, the microstructural and mechanical properties of the welded joint after A–DSUIT were comprehensively improved. The microhardness and tensile strength of the welded joint reached 200 HV and 615 MPa, respectively, for an increase of 45.8% and 61.8%, respectively. Observation of the fractures of the tensile specimens under the different treatment processes showed that the fractures before the aging treatment were mainly ductile fractures while those after were mainly brittle fractures. After DSUIT of the welded joints, a clear and dense plastic deformation layer was observed in the fracture of the tensile specimens and effectively improved the tensile properties of the welded joints. Under the EBSD characterization, the larger the residual compressive stress near the ultrasonic impact surface, the smaller the grain diameter and misorientation angle, and the lower the texture strength. Finally, after A–DSUIT, the hardness and tensile properties improved the most.

The Effect of Residual Stress on Fatigue Life of Welded Cruciform Joints of 16MnR for Train Bogie

2013 ◽  
Vol 815 ◽  
pp. 695-699 ◽  
Author(s):  
Ying Xia Yu ◽  
Bo Lin He ◽  
Jian Ping Shi ◽  
Jing Liu
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Fatigue Life ◽  
Load Ratio ◽  
Fatigue Tests ◽  
Residual Tensile Stress ◽  
Cruciform Joints ◽  
Weld Toe ◽  
Deformation Layer ◽  
Cruciform Joint

The weld toe surface and its nearby area of welded cruciform joints were treated by ultrasonic impact. Under the same stress concentration and after heat treatment to eliminate residual stress, the effect of residual stress on the fatigue life of joint was researched. The fatigue tests are performed on the joints of 16MnR both for the un-treated and treated joints by using EHF-EM200K2-070-1A type fatigue tester when the load ratio is 0.1, frequency is 10Hz. The experimental results indicate that the severe plastic deformation in the vicinity of weld toe surface was formed by impact treating for 2 minutes, the thickness of the plastic deformation layer is about 60μm. Residual tensile stress in the weld toe surface can be changed to residual compressive stress by impact treatment. The fatigue life of welded joint is 0.260×106cycle, and the fatigue life of treated joint is 0.499×106cycle. Compared to the un-treated joint, the fatigue life of treated joint has been increased by 91.92%. The residual stress contributed to fatigue life is about 16%. Residual stress has great effect on the fatigue life of welded cruciform joint.

scholarly journals Notch effect of welded joint

2018 ◽  
Vol 165 ◽  
pp. 21003 ◽  
Author(s):  
Vladimír Chmelko ◽  
Matúš Margetin ◽  
Michal Harakal’
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Weld Joint ◽  
Welded Joints ◽  
Structural Changes ◽  
Welded Joint ◽  
Base Material ◽  
Notch Effect ◽  
Internal Defects ◽  
Technological Factors

In general, the welded joints are multifactorial notches. This study is focused to separate the geometrical influence (when the weld can be seen on the surface) and technological factors (internal defects of the weld, structural changes of the material and residual stress) on its fatigue life. Proposed methodology of this separation comes out from the cyclic test of three specimens – group with existing weld, group without weld joint (base material) and another group where was removed outer geometry of the weld.

scholarly journals Effect of Welding Residual Stress on Along-Wind Fatigue Life of Welded Joints in Guyed Mast

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Weilian Qu ◽  
Min Wang ◽  
Qiang Zhou
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Stress Field ◽  
Structural Steel ◽  
Welded Joints ◽  
Welded Joint ◽  
Welding Residual Stress ◽  
Wind Effect ◽  
Induced Stress ◽  
Guyed Mast

On the premise of only considering along-wind effect on guyed mast, the influence of welding residual stress on the fatigue life of welded joints is evaluated in this paper. Since the sum of residual stress and along-wind-induced dynamic stress exceeds the yield strength of structural steel, the effect of residual stress relaxation is included in the numerical analysis. The multiscale finite element analysis of guyed mast is developed in order to capture accurately stress field distribution of welded joint for the “welding-wind-induced” case in which both residual stress and along-wind-induced stress are taken into consideration, and the stress response characteristics at fatigue critical point of welded joints are pointed out. It is found that the “welding-wind-induced” stress field of welded joint can be approximately considered as multiaxial proportional loading state and hence the stress-based von Mises criterion can be adopted to evaluate the fatigue life of welded joints. Based on the S-N curve of stress fatigue life for welded specimens with structural steel commonly used in guyed masts, the fatigue damage of key welded joints is predicted, and as a consequence, the influence of welding residual stress on the fatigue life of welded joints is discussed.

Effect of Ultrasonic Impact Treatment on Corrosion Resistance of Welded Joints of 16MnR Steel

2013 ◽  
Vol 815 ◽  
pp. 689-694 ◽  
Author(s):  
Bo Lin He ◽  
Ying Xia Yu ◽  
Jing Liu ◽  
Jian Ping Shi
Keyword(s):  
Aqueous Solution ◽  
Plastic Deformation ◽  
Corrosion Resistance ◽  
Weld Seam ◽  
Welded Joint ◽  
Residual Tensile Stress ◽  
Ultrasonic Impact Treatment ◽  
Weld Toe ◽  
The Impact ◽  
Deformation Layer

The weld seam and weld toe surface were treated by ultrasonic impact method. The contrast corrosion tests were performed in 3.5% NaCl aqueous solution both for the un-treated and treated joint. The experimental results indicate that the severe plastic deformation on the surface of weld seam and weld toe were formed by ultrasonic impact for different time, the maximum depth of the plastic deformation layer is about 300μm. Residual tensile stress in the surface of weld seam and weld toe can be changed to residual compressive stress by impact treatment, and the grain in the surface of welded joint could be refined. Compared to the un-treated joint, when the impact current is 1.2A and 1.5A, respectively, the corrosion rate of treated joint was reduced by 22.67%, 54.59%, 43.99% and 33.92%, 56.54%, 49.29%, respectively for 10, 20 and 30 min. treating. The corrosion resistance of welded joint has a certain relationship with the residual stress on the surface of welded joint. The ultrasonic impact treatment has distinct effect on the corrosion resistance of 16MnR welded joint.

scholarly journals Investigation of the Residual Stress in a Multi-Pass T-Welded Joint Using Low Transformation Temperature Welding Wire

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 325
Author(s):  
Zhongyuan Feng ◽  
Ninshu Ma ◽  
Seiichiro Tsutsumi ◽  
Fenggui Lu
Keyword(s):  
Residual Stress ◽  
Welded Joints ◽  
Transformation Temperature ◽  
Compressive Residual Stress ◽  
Welded Joint ◽  
Numerical Study ◽  
Weld Zone ◽  
Welding Wire ◽  
Finish Temperature ◽  
Welding Materials

We investigated whether low transformation temperature (LTT) welding materials are beneficial to the generation of compressive residual stress around a weld zone, thus enhancing the fatigue performance of the welded joint. An experimental and numerical study were conducted in order to analyze the residual stress in multi-pass T-welded joints using LTT welding wire. It was found that, compared to the conventional welded joint, greater tensile residual stress was induced in the flange plate of the LTT welded joints. This was attributed to the reheat temperature of the LTT weld pass during the multi-pass welding. The formerly-formed LTT weld pass with a reheat temperature lower than the austenite finish temperature converted the compressive residual stress into tensile stress. The compressive residual stress was generated in the regions with a reheat temperature higher than the austenite finish temperature, indicating that LTT welding materials are more suitable for single-pass welding.

scholarly journals Influence of turning tool wear on the surface integrity and anti-fatigue behavior of Ti1023

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110112
Author(s):  
Li Xun ◽  
Wang Ziming ◽  
Yang Shenliang ◽  
Guo Zhiyuan ◽  
Zhou Yongxin ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Plastic Deformation ◽  
Titanium Alloy ◽  
Fatigue Life ◽  
Tool Wear ◽  
Surface Integrity ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Machined Surface ◽  
Deformation Layer

Titanium alloy Ti1023 is a typical difficult-to-cut material. Tool wear is easy to occur in machining Ti1023, which has a significant negative effect on surface integrity. Turning is one of the common methods to machine Ti1023 parts and machined surface integrity has a direct influence on the fatigue life of parts. To control surface integrity and improve anti-fatigue behavior of Ti1023 parts, it has an important significance to study the influence of tool wear on the surface integrity and fatigue life of Ti1023 in turning. Therefore, the effect of tool wear on the surface roughness, microhardness, residual stress, and plastic deformation layer of Ti1023 workpieces by turning and low-cycle fatigue tests were studied. Meanwhile, the influence mechanism of surface integrity on anti-fatigue behavior also was analyzed. The experimental results show that the change of surface roughness caused by worn tools has the most influence on anti-fatigue behavior when the tool wear VB is from 0.05 to 0.25 mm. On the other hand, the plastic deformation layer on the machined surface could properly improve the anti-fatigue behavior of specimens that were proved in the experiments. However, the higher surface roughness and significant surface defects on surface machined utilizing the worn tool with VB = 0.30 mm, which leads the anti-fatigue behavior of specimens to decrease sharply. Therefore, to ensure the anti-fatigue behavior of parts, the value of turning tool wear VB must be rigorously controlled under 0.30 mm during finishing machining of titanium alloy Ti1023.

scholarly journals Influence of Shielding Gas on Microstructure and Properties of GMAW DSS2205 Welded Joints

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2671
Author(s):  
Xin-Yu Zhang ◽  
Xiao-Qin Zha ◽  
Ling-Qing Gao ◽  
Peng-Hui Hei ◽  
Yong-Feng Ren
Keyword(s):  
Corrosion Resistance ◽  
Welded Joints ◽  
Welded Joint ◽  
Crystal Defects ◽  
Shielding Gas ◽  
Electrochemical Tests ◽  
Corrosion Resistance Property ◽  
Mechanical Properties And Corrosion ◽  
Ar Gas ◽  
Welded Seam

In the present study, the microstructures and properties of DSS 2205 solid wire MIG welded samples prepared in different shielding gases (pure Ar gas, 98%Ar + 2%O2 and 98%Ar + 2%N2) were investigated for improving the weldability of DSS 2205 welded joint. The work was conducted by mechanical property tests (hardness and tensile test) and corrosion resistance property tests (immersion and electrochemical tests). The results show that adding 2%O2 into pure Ar gas as the shielding gas decreases crystal defects (faults) and improves the mechanical properties and corrosion resistance of the welded joints. Phase equilibrium and microstructural homogeneity in welded seam (WS) and heat-affected zone (HAZ) can be adjusted and the strength and corrosion resistance of welded joints increased obviously by adding 2%N2 to pure Ar gas as the shielding gas. Compared with DSS 2205 solid wire MIG welding in 98%Ar + 2%O2 mixed atmosphere, the strength and corrosion resistance of welded joints are improved more obviously in 98%Ar + 2%N2 mixed atmosphere.

Effect of Residual Stress or Plastic Deformation History on Fatigue Life Simulation of Pipeline Dents

2018 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Rick Wang
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Strain History ◽  
Deformation History ◽  
Stress Strain ◽  
Element Analysis ◽  
Fea Model

Mechanical dents often occur in transmission pipelines, and are recognized as one of major threats to pipeline integrity because of the potential fatigue failure due to cyclic pressures. With matured in-line-inspection (ILI) technology, mechanical dents can be identified from the ILI runs. Based on ILI measured dent profiles, finite element analysis (FEA) is commonly used to simulate stresses and strains in a dent, and to predict fatigue life of the dented pipeline. However, the dent profile defined by ILI data is a purely geometric shape without residual stresses nor plastic deformation history, and is different from its actual dent that contains residual stresses/strains due to dent creation and re-rounding. As a result, the FEA results of an ILI dent may not represent those of the actual dent, and may lead to inaccurate or incorrect results. To investigate the effect of residual stress or plastic deformation history on mechanics responses and fatigue life of an actual dent, three dent models are considered in this paper: (a) a true dent with residual stresses and dent formation history, (b) a purely geometric dent having the true dent profile with all stress/strain history removed from it, and (c) a purely geometric dent having an ILI defined dent profile with all stress/strain history removed from it. Using a three-dimensional FEA model, those three dents are simulated in the elastic-plastic conditions. The FEA results showed that the two geometric dents determine significantly different stresses and strains in comparison to those in the true dent, and overpredict the fatigue life or burst pressure of the true dent. On this basis, suggestions are made on how to use the ILI data to predict the dent fatigue life.

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