scholarly journals Shielding Gas and Inclusion Content Effects on Impact Toughness and Tensile Properties of 410NiMo Steel Welds

2021 ◽  
Vol 100 (01) ◽  
pp. 52-62
Author(s):  
BOUCHRA TENNI ◽  
◽  
MYRIAM BROCHU ◽  
STÉPHANE GODIN ◽  
DENIS THIBAULT
Keyword(s):  
Impact Toughness ◽  
Tensile Properties ◽  
Arc Welding ◽  
Postweld Heat Treatment ◽  
Weld Strength ◽  
Shielding Gas ◽  
Absorbed Energy ◽  
Inclusion Content ◽  
Flux Cored Arc Welding ◽  
Welding Processes

The effect of shielding gas on the mechanical and microstructural characteristics of ER410NiMo martensitic stainless steel weldments was investigated. Three weldments with various inclusion contents were manufactured using different shielding gas compositions and welding processes: gas metal arc welding (GMAW) with 100% argon (Ar), GMAW 85% Ar/15% carbon dioxide (CO2), and flux cored arc welding (FCAW) 75% Ar/25% CO2. The inclusions in each weldment were characterized by means of scanning electron microscope observations and energy-dispersive spectroscopy analysis. The weldments underwent postweld heat treatment, after which the chemical composition and reformed austenite proportion were measured to account for microstructural effects. Hardness measurements, tensile tests, and impact toughness tests using the Charpy method were performed. The results showed that the Charpy V-notch (CVN) absorbed energy decreases with increasing inclusion content. The highest CVN absorbed energy, 195 J, was obtained for the GMAW 100% Ar weld, which had the lowest inclusion content. GMAW 85% Ar/15% CO2, with four times more inclusions than the former, had a CVN absorbed energy of 63 J. The current manufacturing process, FCAW 75% Ar/25% CO2, was found to have an inclusion content three times higher than the GMAW 100% Ar weld but a CVN absorbed energy of 66 J, which is close to the GMAW 85% Ar/15% CO2 weld. The results showed that using GMAW 100% Ar as a replacement to FCAW 75% Ar/25 % CO2 would lead to a three-fold improvement in terms of absorbed impact energy. The effect of inclusions on tensile properties, which was not clearly identified as several factors, in addition to inclusion content, affects the weld strength and elongation. Overall, the yield and ultimate tensile strengths differed slightly: 724 and 918 MPa for GMAW 100% Ar, 746 and 927 MPa for GMAW 85% Ar/15% CO2, and 711 and 864 MPa for FCAW 75% Ar/25% CO2, respectively.

Limitations of the Schlieren technique for shielding gas flow visualization in arc welding processes

2021 ◽  
Author(s):  
Mateus Barancelli Schwedersky ◽  
Álisson Fernandes da Rosa ◽  
Marcelo Pompermaier Okuyama ◽  
Régis Henrique Gonçalves e Silva
Keyword(s):  
Flow Visualization ◽  
Arc Welding ◽  
Gas Flow ◽  
Shielding Gas ◽  
Schlieren Technique ◽  
Welding Processes

Optimization of Flux Cored Arc Welding Process Parameter Using Genetic and Memetic Algorithms

2013 ◽  
Vol 13 (4) ◽  
pp. 239-250 ◽  
Author(s):  
T. Kannan ◽  
N. Murugan ◽  
B. N. Sreeharan
Keyword(s):  
Arc Welding ◽  
Welding Process ◽  
Memetic Algorithms ◽  
Optimization Techniques ◽  
Low Carbon ◽  
Robotic Welding ◽  
Bead Width ◽  
Flux Cored Arc Welding ◽  
Arc Welding Process ◽  
Welding Processes

AbstractMost of the manufacturing enterprises indulge in the bonding of metals during the production process. This makes welding one of the most important processes in industries. Subsequently, due to the high usage of welding process, industrial engineers desire to optimize the parameters concerned to achieve the desired weld bead characteristics. This paper focuses on optimization of flux cored arc welding process parameters, which are used for deposition of duplex stainless steel on low carbon structural steel plates. Experiments were conducted based on central composite rotatable design and mathematical models were developed using multiple regression method. Further, optimization with objectives as minimizing percentage dilution, maximizing height of reinforcement and bead width was carried out using genetic algorithm and memetic algorithm. This problem was formulated as a multi objective, multivariable and non-linear programming problem. The algorithms were implemented using basic functions of C language making it highly reliable, adoptable, very user friendly and extendable to other welding processes such as GMAW, GTAW, robotic welding, etc. The adopted optimization techniques were further compared based on various computational factors.

scholarly journals The State of the Art of Underwater Wet Welding Practice: Part 1

2021 ◽  
Vol 100 (4) ◽  
pp. 132-141
Author(s):  
EZEQUIEL CAIRES PEREIRA PESSOA ◽  
◽  
STEPHEN LIU
Keyword(s):  
Research And Development ◽  
Weld Metal ◽  
Arc Welding ◽  
Structural Steels ◽  
Friction Stir ◽  
Underwater Wet Welding ◽  
Class A ◽  
Metal Arc Welding ◽  
Flux Cored Arc Welding ◽  
Welding Processes

Developments in underwater wet welding (UWW) over the past four decades are reviewed, with an emphasis on the research that has been conducted in the last ten years. Shielded metal arc welding with rutile-based coated electrodes was established as the most applied process in the practice of wet welding of structural steels in shallow water. The advancements achieved in previous decades had already led to control of the chemical com-position and microstructure of weld metals. Research and development in consumables formulation have led to control of the amount of hydrogen content and the level of weld porosity in the weld metal. The main focus of research and development in the last decade was on weldability of naval and offshore structural steels and acceptance of welding procedures for Class A weld classification according to American Welding Society D3.6, Under-water Welding Code. Applications of strictly controlled welding techniques, including new postweld heat treatment procedures, allowed for the welding of steels with carbon equivalent values greater than 0.40. Classification societies are meticulously scrutinizing wet welding procedures and wet weld properties in structural steels at depths smaller than 30 m prior to qualifying them as Class A capable. Alternate wet welding processes that have been tested in previous decades — such as friction stir welding, dry local habitat, and gas metal arc welding —have not achieved great success as originally claimed. Al-most all of the new UWW process developments in the last decade have focused on the flux cored arc welding (FCAW) process. Part 1 of this paper covers developments in microstructural optimization and weld metal porosity control for UWW. Part 2 discusses the hydrogen pickup mechanism, weld cooling rate control, design, and qualification of consumables. It ends with a description of the advancements in FCAW applications for UWW.

Hexavalent Chromium Exposure Levels Resulting from Shipyard Welding

1998 ◽  
Vol 14 (04) ◽  
pp. 246-254
Author(s):  
Bhaskar Kura ◽  
Praveen Mookoni
Keyword(s):  
Hexavalent Chromium ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Task Group ◽  
Health Administration ◽  
Metal Arc Welding ◽  
Flux Cored Arc Welding ◽  
Exposure Levels ◽  
The Impact ◽  
Welding Processes

The Occupational Safety and Health Administration is expected to reduce permissible exposure limits of hexavalent chromium from 100 ng/m3between 5 to 0.5 fig/m3. A Navy Industry Task Group study revealed that the impact of proposed regulations on the shipbuilding industry is significant. The estimated cost of compliance by the Navy facilities could be as much as $46 Million/year besides a one-time cost of about $22 Million. Also, the task group estimated that the cost of $9 Million. This paper presents the results of a study undertaken at the University of New Orleans in support of the Navy/Industry Task Group efforts. The study included assessments of Cr(VI) exposure levels for two specific welding processes and three welding scenarios. Airborne particulate matter was collected using personal samplers for two specific welding processes, Gas Metal Arc Welding and Flux-Cored Arc Welding. Two base metals, HY100 and DH36, were considered for Flux-Cored Arc Welding and one base metal, HY100, was considered for Gas Metal Arc Welding. The samples were analyzed for Cr(VI) using OSHA Method 215. Based on the data generated, it can be concluded that Gas Metal Arc Welding and Flux-Cored Arc Welding on HY100 steel result in 8-hr. worker exposures less than 0.5 fig/m3 in a laboratory type setting, though the same levels of exposure may be difficult to be achieved in the field. Flux-Cored Arc Welding on DH36 resulted in exposure above 0.5 ng/m3, again in laboratory type setting.

Flux-cored arc welding processes analysis of a shipyard

2016 ◽  
pp. 801-805
Author(s):  
P Lameira ◽  
C Benjamin ◽  
E Loureiro ◽  
H Moraes ◽  
N Figueiredo ◽  
...  
Keyword(s):  
Arc Welding ◽  
Flux Cored Arc Welding ◽  
Welding Processes

A Processing Approach Incorporating Copper Backing-Wheel Device in Submerged Arc Welding for Manufacturing Cryogenic Storage Tanks

2014 ◽  
Vol 705 ◽  
pp. 106-111
Author(s):  
Supphachan Rajsiri ◽  
Mayuree Chomjanngam ◽  
Sittiphun Tuntawiroon
Keyword(s):  
Arc Welding ◽  
Submerged Arc Welding ◽  
Storage Tanks ◽  
Welding Temperature ◽  
New Approach ◽  
Cryogenic Storage ◽  
Processing Approach ◽  
Flux Cored Arc Welding ◽  
Welding Processes ◽  
Submerged Arc

A processing approach using a copper backing-wheel device was developed to aid the fabrication process of industrial cryogenic storage tanks manufactured under the ASME Section VIII Division 1. This research focused on the welding processes related to the cylindrical-body assembly. Two processing steps involving the root-run formation and the replacement with a sound outer-circumference joint were studied. Initially, tank fabrication is achieved through the application of both flux-cored arc welding and submerged arc welding. A new processing approach was proposed with the modified method in cross-section preparation, and a low-cost reusable copper backing-wheel device was developed to facilitate the root-run formation using only submerged arc welding. Temperature gradient through the device components along the heat-conduction path was monitored to assure the conductivity of the backing device. The results suggest that the proposed approach reduced manufacturing time by removing the initial flux-cored arc welding process used in the conventional welding method. As an effect, the new approach show promise reduces the overall manufacturing cost of tank fabrication. Based on radiographic testing of tanks fabricated using the new approach found that circumference joints required little or no welding repair suggesting higher joint quality.

Investigation of Microstructure and Hardness Properties of Hardfacing Surface on SCM 440 Alloy Steel by Using Metal Active Gas and Flux Cored Arc Welding Processes

2017 ◽  
Vol 728 ◽  
pp. 31-35 ◽  
Author(s):  
Siva Sitthipong ◽  
Prawit Towatana ◽  
Amnuay Sitticharoenchai
Keyword(s):  
Alloy Steel ◽  
Arc Welding ◽  
Welding Process ◽  
High Strength ◽  
Side Plate ◽  
Weld Metals ◽  
Flux Cored Arc Welding ◽  
The Difference ◽  
Arc Welding Process ◽  
Welding Processes

This research aimed to investigate the microstructure and hardness properties of hardfacing surface on SCM440 alloy steel by using metal active gas and flux cored arc welding processes. Due to the difficulty of welding the high strength steel, the changes in base metals’ microstructures were found after welding. Preheating the specimens at 350°C and post weld heat treatment the specimens at 550°C were performed for 1 hour, to reduce the residual stresses and avoid the undesired formation of microstructures. The weld metals’ microstructures that were found from both welding processes are acicular ferrite, polygonal ferrite and side plate ferrite. The hardness value of weld metal resulted from flux cored arc welding process is higher than that of the metal active gas welding process. Each welding process produced different quantities of weld metals’ microstructures, causing the difference in hardness values. The data will be used for investigating and improving parameters of shaft repairing, in order to use it more effectively.

scholarly journals Sensitization and Corrosion of 409M Ferritic Stainless Steel by Different Welding Processes

2019 ◽  
Vol 8 (2) ◽  
pp. 3904-3911
Keyword(s):  
Stainless Steel ◽  
Tensile Properties ◽  
Ferritic Stainless Steel ◽  
Arc Welding ◽  
Research Work ◽  
Chemical Exposure ◽  
Constant Current ◽  
Metal Arc Welding ◽  
Acidic Environments ◽  
Welding Processes

The aim of this research work was to analyze the sensitization due to the effect of welding (Shielded Metal Arc Welding, Gas Tungsten Arc Welding & Gas Metal Arc Welding) heat in heat affected zone area in terms of metallurgical properties, mechanical properties and corrosion of base metal comparatively. Also the effect of different chemicals / acidic environments on tensile properties was investigated. The plates of 3 mm thickness of 409M Ferritic Stainless Steel welded at constant current of 90A by three different welding processes with the same filler metal. The microstructure observation was made after Marble reagent chemical etched. Then tensile properties were investigated and comparative analysis done between the tensile properties i.e. before and after the chemical exposure given to it with the parent metal. After completion of experimental work it is found that SMAW, GMAW and GTAW have affected the microstructure of 409M Ferritic Stainless Steel. Due to the acidic environments/ Chemical exposures the strength and ductility of the metal affects. But comparatively GTAW has shown better process than GMAW and SMAW for welding of 409M Ferritic Stainless Steel. It should be used with caution in sulphuric acid environments than chloride environments to resist corrosion.

scholarly journals Long-term Metal Fume Exposure Assessment of Workers in a Shipbuilding Factory

2021 ◽  
Author(s):  
Ying-Fang Wang ◽  
Yu-Chieh Kuo ◽  
Lin-Chi Wang
Keyword(s):  
Exposure Assessment ◽  
Arc Welding ◽  
Emission Rates ◽  
Bayesian Decision ◽  
Operation Condition ◽  
Total Chromium ◽  
Term Operation ◽  
Flux Cored Arc Welding ◽  
Welding Processes

Abstract This study aims to assess the metal fume exposure of welders and to determine exposure rates for similar exposure groups in a shipyard through the use of Near-field/Far-field (NF/FF) mathematical models and Bayesian decision analysis (BDA) technique. Emission rates of various metal fumes (i.e., total chromium (Cr), iron (Fe), lead (Pb), manganese (Mn), and nickel (Ni)) were experimentally determined for the gas metal arc welding and flux cored arc welding processes, which are commonly used in shipyards. Then the NF/FF field model which used the emission rates were further validated by welding simulation experiment, and together with long-term operation condition data obtained from the investigated shipyard, the predicted long-term exposure concentrations of workers was established and used as the prior distribution in the BDA. Along with the field monitoring metal fume concentrations which served as the likelihood distribution, the posterior decision distributions in the BDA were determined and used to assess workers’ long-term metal exposures. Results show that welders’ Fe, Mn and Pb exposures were found to exceed their corresponding action levels with a high probability, indicating preventive measures should be taken immediately. The proposed approach provides a universal solution for conducting exposure assessment with usual limited number of personal exposure data.

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