scholarly journals EFFECTS OF METAL INERT GAS WELDING PARAMETERS ON SOME MECHANICAL PROPERTIES OF AUSTENITIC STAINLESS STEEL IN ACIDIC ENVIRONMENT

2017 ◽  
Vol 36 (3) ◽  
pp. 835-843
Author(s):  
IMB Omiogbemi ◽  
DS Yawas ◽  
IM Dagwa ◽  
FG Okibe

The purpose of the present study is to investigate the effects of metal inert gas (MIG) welding parameters on the mechanical properties (hardness, tensile and impact) of type 304 austenitic stainless steel (ASS) immersed in 0.5M hydrochloric acid at ambient temperature. The MIG welding was applied to 3mm thick ASS. The dimensions of the samples were 50mm x 15mm x 3mm and 120mm x 15mm x 3mm rectangular bars each for impact, hardness and tensile tests and for immersion in the medium. Design Expert Software, Scanning Electron Microscopy (SEM), Rockwell Hardness Test, Monsanto Tensometer and Izod Impact Test were used to determine the interactions of parameters, microstructural analysis and optimal performances of the parameters respectively. Experimental results indicate that tensile strength increased with increase in welding parameters from 120MN/m2 to 133MN/m2 at speed of 40cm/min and current of 110. when the properties are compared with varying weld parameters adopted in joint’s weld operations, there was a pattern displayed among the weld parameters with C3 (19.7HRA, 203N/mm2 and 19.7J )and C4 (14.9 HRA, 189N/mm2 and 14.9J) consistently coming out as the parameter producing an ASS weld joint with the best mechanical properties of hardness, tensile and impact strength. Surface corrosion deposit composition was analyzed with the SEM paired with energy dispersive spectrometer (EDS) to ascertain microstructural behavior of the material.   http://dx.doi.org/10.4314/njt.v36i3.25

Author(s):  
Rupinder Singh ◽  
Sehijpal Singh

Stainless steels are considered to have very good resistance to general and localized corrosion due to their chromium content. This property of corrosion resistance constitutes the main criterion for selecting austenitic grades of steels for service in the chemical, nuclear and aerospace industries although their mechanical properties are relatively modest. However, this resistance can degrade when structural components manufactured from these steels are used in a chemically aggressive environment, especially when service involves exposure to high temperatures like in welding. This exposure gives rise to precipitation of chromium carbides producing chromium depletion at grain boundaries that brings about the inter-granular corrosion or sensitization of these materials. Austenitic stainless steel (316L) is one of the corrosion resistance material used extensively in the oil production, chemical and power generation industries for transportation and reservoir of corrosive products. In spite of its corrosion resistance property there exist severe problems of sensitization. In the present work an effort has been made to reduce the effect of sensitization in Tungsten Inert Gas welding of Austenitic stainless steel (316L). Three welding procedures (namely conventional, back step and skip welding) in Tungsten Inert Gas welding have been used to control exposure time of the weld pool to higher temperatures, in order to study the effect of sensitization on mechanical properties (such as tensile strength, yield strength, percentage elongation and hardness). The results of this study suggested that the better mechanical properties were attained by the skip welding procedure and recommended welding parameters are 90 Amp current and 10 L/min of gas flow rate for a 5 mm thick work piece. Noticeable change in amount/extent of sensitization was observed using a scanning electron microscope (SEM) analysis within the various welding specimens prepared using the various procedures. Further mechanical properties (like strength and hardness) have been correlated with the extent of sensitization, which show remarkable decreases when the amount/extent of sensitization increases.


Author(s):  
Sudipto Chaki ◽  
Dipankar Bose

In the present work, artificial neural networks (ANN) have been used to model the complex relationship between input-output parameters of metal inert gas (MIG) welding processes. Four ANN training algorithms such as back propagation neural network (BPNN) with gradient descent momentum (GDM), BPNN with Levenberg Marquardt (LM) algorithm, BPNN with Bayesian regularization (BR), and radial basis function networks (RBFN) method have been used for prediction modelling. An experimentation based on full factorial experimental design has been conducted on MIG welding of austenitic stainless steel of grade-304 where welding current, welding speed, and voltage have been considered as input parameters, and tensile strength has been considered as measurable output parameter. The dataset so constituted is used for ANN modelling. Altogether, 40 different ANN architectures have been trained and tested using the above-mentioned algorithms, and 3-11-1 ANN architecture trained using BPNN with BR has been considered to show best prediction capability with mean % absolute error of 0.354%.


2018 ◽  
Vol 8 (3) ◽  
pp. 3064-3072 ◽  
Author(s):  
A. Hdhibi ◽  
K. Touileb ◽  
R. Djoudjou ◽  
A. Ouis ◽  
M. L. Bouazizi ◽  
...  

Tungsten inert gas (TIG) is a wide common process used in fabrication due to its low cost equipment, high quality and accuracy welds but has low productivity related to the low penetration depth in single pass. A new perspective, the Activated Tungsten Inert Gas (ATIG), in which the same equipment as TIG is used, except that a thin layer of activated flux is deposited on a workpiece surface. In this work, eight kinds of oxides were tested on 316L austenitic stainless steel. Three levels of welding current were used to study the effect of different activating fluxes on weld bead geometry and mechanical properties. X-ray Photoelectron Spectroscopy (XPS) was used for the first and the second level energy for different ATIG welds to analyze the relationship between the weld shape and oxygen content in welds. The experimental results showed that the weld profile is related to the thermodynamic stability of selected oxides and in relation to the energy provided. ATIG with TiO2, SiO2, MnO2 oxides presented the deepest welds followed by Cr2O3, Fe2O3, and ZnO. Finally ZrO2, CaO oxides had no effect on the weld depth. The ATIG welded joint showed better tensile strength than TIG. The ATIG hardness measurements carried out showed also better if not the same as TIG weld except for the Silicon oxide weld. Results of the impact test showed that, except for the titanium dioxide TiO2 which has a good benefit, the weldment using the other oxide fluxes exhibits worse withstanding to sudden shock than TIG welding.


Alloy Digest ◽  
1999 ◽  
Vol 48 (9) ◽  

Abstract ALZ 305 is an austenitic stainless steel with excellent formability and good corrosion resistance, toughness, and mechanical properties. The higher amount of nickel in this grade enables high deep-drawing deformation without intermediate annealing. This datasheet provides information on composition, physical properties, and elasticity. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-762. Producer or source: ALZ nv.


Alloy Digest ◽  
1999 ◽  
Vol 48 (8) ◽  

Abstract ALZ 316 is an austenitic stainless steel with good formability, corrosion resistance, toughness, and mechanical properties. It is the basic grade of the stainless steels, containing 2 to 3% molybdenum. After the 304 series, the molybdenum-containing stainless steels are the most widely used austenitic stainless steels. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-756. Producer or source: ALZ nv.


Alloy Digest ◽  
2001 ◽  
Vol 50 (4) ◽  

Abstract ALZ 321 is an austenitic stainless steel with good cold formability, corrosion resistance, toughness, and mechanical properties. The addition of titanium improves the resistance to intergranular corrosion in welds and slower cooling sections. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on forming, heat treating, and machining. Filing Code: SS-821. Producer or source: ALZ nv.


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