Numerical Simulation of Residual Stresses in Single Pass Butt-Weld of Dissimilar Pipe Joint during the Fusion Welding Process

2011 ◽  
Vol 314-316 ◽  
pp. 1034-1037 ◽  
Author(s):  
Min Ke Sun ◽  
Dong Sheng Zhao ◽  
Yu Jun Liu

Dissimilar metal welded joints are widely used in engineering structures nowadays. Among the various types of material combinations, dissimilar welded joints of carbon steel and austenitic stainless steel are very common in shipbuilding, nuclear and chemical industries. In this study the finite element software MSC.Marc is employed to calculate the welding residual stresses in dissimilar butt-welded Q235 steel and 304 stainless steel pipes with different welding currents. The calculation results indicate that the welding residual stresses present asymmetric distribution, peaks of residual stresses on inner surface tend to be in 304 stainless side which can be significant higher than the yield stresses of parent metals. Changing in welding current does not have a significant effect on the peak of stress in weld center line.

2015 ◽  
Vol 45 (1) ◽  
pp. 19-23
Author(s):  
Rupinder Singh ◽  
Sunpreet Singh

The purpose of the present investigations is to study statistically controlled solution (from sensitization point of view) for 304 stainless steel (SS) joints using resistance spot welding process (RSWP). Starting from the parametric optimization of RSWP parameters (based upon Taguchi design), welded joints were prepared for functional checking. The output parameters selected for controlling the sensitization were hardness and tensile strength of welded joints. The results are supported by SEM analysis. Further the study suggests that the RSWP was found to be under statistical control (at optimized settings suggested by Taguchi design) as regard to sensitization of welded joint is concerned.


2012 ◽  
Vol 710 ◽  
pp. 620-625 ◽  
Author(s):  
Muralimohan Cheepu ◽  
V. Muthupandi ◽  
S. Loganathan

Friction welding is a solid state joining process and it is best suited for joining dissimilar metals. It overcomes the problems associated with the conventional fusion welding processes. The joining of dissimilar metals using fusion welding processes produce brittle intermetallic precipitates at the interface which reduce the mechanical strength. Various aerospace, nuclear, chemical and cryogenic applications demand joints between titanium and stainless steel. Direct joining of these metals results in brittle intermetallics like FeTi and FexTiy, at the weld interface, which is to be avoided in order to achieve improved properties of the joints. Present study involves joining of two industrially important dissimilar metals such as commercially pure titanium and 304 stainless steel by friction welding with electroplated nickel coating as interlayer that can prevent the brittle intermetallic formation. Microstructural details of the interfaces of the friction welded joints were studied by optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) technique and X-ray diffraction (XRD). Microhardness survey was carried out across the joints and tensile test was conducted to assess the mechanical properties of the joints. Fractography studies were carried out on the fracture surfaces of the joints to know the region of failure as well as the mode of failure. XRD patterns indicate the presence of intermetallics in the friction welded joints. These two metals were successfully joined by having electroplated nickel as interlayer. The weld interface on titanium side contained Ti-Ni intermetallics layers, in which the hardness of the weld metal showing the higher value than the base metals. Fractography study conducted on the fracture surfaces created due to pull test reveals that the failure is by brittle fracture and occurred at the intermetallics layer. The maximum strength of the joints achieved for 30 μm and 50 μm thick electroplated nickel interlayers are 242 MPa and 308 MPa, respectively.


2020 ◽  
Vol 53 (7-8) ◽  
pp. 1183-1193
Author(s):  
Hitesh Arora ◽  
Rupinder Singh ◽  
Gurinder Singh Brar

The major concern in the high tech industries like oil and petroleum industries, automobiles, aeronautical, and nuclear power plants is the control of the defects like distortion in the welded joints and residual stresses occur due to arc welding on the circumferential joints of the thin pipes. Three-dimensional non-linear thermal and thermomechanical numerical simulations are conducted for the tungsten inert gas welding process of SS-304 stainless steel pipes. In this article, numerical analysis of the distribution of the temperature and the welding residual stress fields induced after the welding is done. Study on the effect of the welding heat input by varying the welding parameters (like welding current and welding speed) based on finite element simulations is conduit to examine the results on the residual stresses which is also called as the ‘locked-in’ stresses. The precision of the finite element model is validated for the welding residual stresses. The intention of this study is to provide the information to verify the validity of ongoing process circumferential manufacturing technology for thin-walled pipes, so to avoid the failure of these kinds of structures which are in service because of these intrinsic stresses.


Author(s):  
Sorush Niknamian

Nowadays, welding of dissimilar metals has become significant. In this process, a number of parameters including but not limited to type of electrode, amount of current, preheating temperature, and welding rate, that are essential to be taken into account. For welding of dissimilar metals, various methods are exploited including shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW). The stimulus for studying welding of 304L stainless steel to pure copper originates from difficulties in joining copper parts of           water-circulating molds to their steel part. In this study, the welding is performed on plates of steel and copper using SMAW, GTAW and combined SMAW+GTAW welding methods with    EL-CuMn2, ENiCrMo-6 and ER70S-4 electrodes. In order to investigate the microstructure and corrosion resistance behavior of welds, the samples were characterized using microstructural study and polarization test. It was observed that among all four welding methods, only combined SMAW+GTAW welding process resulted in successful joint between 304L stainless steel and copper. Both obtained joints possess suitable microstructure and corrosion resistance.


2021 ◽  
Vol 50 (9) ◽  
pp. 2743-2754
Author(s):  
Ashish Jacob ◽  
Sachin Maheshwari ◽  
Arshad Noor Siddiquee ◽  
Abdulrahman Al-Ahmari ◽  
Mustufa Haider Abidi ◽  
...  

Certain age hardenable alloys such as AA7475 cannot be joined with perfection using fusion welding techniques. This requires non-conventional welding technique such as friction stir welding process to join these ‘difficult to weld’ alloys. In this study, three different cooling conditions i.e. cryogenic, sub-zero, and zero-degree Celsius temperature conditions have been analyzed to understand its impact on the welding process. In-process cooling was found to behave effectively and also enhanced the mechanical properties of the welded joints. A stable microstructure was clearly seen in the images observed under the metallurgical microscope. The weld efficiencies were found to be good in each of the samples which are indicative of a strong metallic joint. The effective cooling conditions employed had an overall positive impact on the joint.


2014 ◽  
Vol 627 ◽  
pp. 93-96 ◽  
Author(s):  
Raffaele Sepe ◽  
Enrico Armentani ◽  
Giuseppe Lamanna ◽  
Francesco Caputo

During the last few years various experimental destructive and non-destructive methods were developed to evaluate residual stresses. However it is impossible to obtain a full residual stress distribution in welded structures by means of experimental methods. This disadvantage can be solved by means of computational analysis which allows to determine the whole stress and strain fields in complex structures. In this paper the temperature distribution and residual stresses were determined in a single-pass butt joint welded by GMAW (Gas Metal Arc Welding) process by finite element model (FEM). A 3D finite parametric element model has been carried out to analyze temperature distribution in butt weld joints and thermo-mechanical analyses were performed to evaluate resulting residual stresses. Temperature fields have been investigated by varying an initial preheating treatment. Moreover the technique of “element birth and death” was adopted to simulate the process of filler metal addition The high stresses were evaluated, with particular regard to fusion zone and heat affected zone. The influence of preheating and post-heating treatment on residual stresses was investigated. The residual stresses decrease when preheating temperature increases. The maximum value of longitudinal residual stresses without pre-heating can be reduced about 12% and 38% by using the preheating and post-heating process respectively.


Author(s):  
Tao Mo ◽  
Jingqing Chen ◽  
Pengju Zhang ◽  
Wenqian Bai ◽  
Xiao Mu ◽  
...  

Ultrasonic impact treatment (UIT) is an effective method that has been widely applied in welding structure to improve the fatigue properties of materials. It combines mechanical impact and ultrasonic vibration to produce plastic deformation on the weld joints surface, which introduces beneficial compressive residual stress distribution. To evaluate the effect of UIT technology on alleviating the residual stress of welded joints, a novel numerical analysis method based on the inherent strain theory is proposed to simulate the stress superposition of welding and subsequent UIT process of 304 stainless steel. Meanwhile, the experiment according to the process was carried out to verify the simulation of residual stress values before and after UIT. By the results, optimization of UIT application could effectively reduce the residual stress concentration after welding process. Residual tensile stress of welded joints after UIT is transformed into residual compressive stress. UIT formed a residual compressive stress layer with a thickness of about 0.13 mm on the plate. The numerical simulation results are consistent with the experimental results. The work in this paper could provide theoretical basis and technical support for the reasonable evaluation of the ultrasonic impact on residual stress elimination and mechanical properties improvement of welded joints.


1996 ◽  
Vol 45 (12) ◽  
pp. 1328-1333 ◽  
Author(s):  
Hiromichi HONGO ◽  
Masayoshi YAMAZAKI ◽  
Takashi WATANABE ◽  
Junichi KINUGAWA ◽  
Yoshio MONMA

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