Decisive impact of Filler-free joining processes on the Microstructural evolution, tensile and impact properties of 9Cr-1Mo-V-Nb to 316 L(N) dissimilar joints

2021 ◽  
pp. 095440622110293
Author(s):  
A Venkatakrishna ◽  
AK Lakshminarayanan ◽  
P Vasantharaja ◽  
M Vasudevan
Keyword(s):  
Weld Metal ◽  
Laser Beam Welding ◽  
Carbon Diffusion ◽  
Comparative Investigation ◽  
Impact Testing ◽  
Dissimilar Joints ◽  
Friction Stir ◽  
Dissimilar Weld ◽  
Transverse Tensile ◽  
Welding Processes

Filler-free (FF) welding processes namely, Activated Tungsten Inert Gas welding (ATIG), Laser Beam Welding (LBW), and Friction Stir Welding (FSW) were utilized for joining the nuclear grade 9Cr-1Mo-V-Nb ferritic-martensitic steel and 316 L(N) austenitic stainless steel. A comparative investigation was made by assessing the weld geometries, metallurgical features, material mixing proportions, carbon diffusion behaviour, and mechanical properties of the post-weld heat-treated (PWHT) dissimilar weld joints. Geometries of the weld zones were observed with the transverse and longitudinal macrographs. Metallurgical features were examined by optical microscopy (OM) and Scanning electron microscopy (SEM). Three-phase microstructures were identified in the dissimilar weld zones (DWZ). The elemental distributions were identified by Energy-dispersive X-ray spectroscopy (EDAX). The mixing proportions of the dissimilar alloys and the formation of δ-ferrite in the dissimilar heat-affected zones (HAZ) and DWZ were analytically quantified. Moreover, the diffusion activity of carbides/interstitial carbon atoms was examined by Secondary ion mass spectroscopy (SIMS). In the FSW joints, the intermingled microstructures are recorded with high and stabilized hardness values as compared to the DWZ of the ATIG and LBW joints. In the transverse tensile test, all FF joints were failed at the 316 L(N) base metal (BM) region. Tensile and impact testing of all weld metal indicated that, the weld metal region of the LBW joint exhibited higher strength and lower toughness as compared to the ATIG and FSW joints. The presence of untransformed, recrystallized fine equiaxed austenite along and refined martensitic structure arranged in an alternate layers within the weld metal region of FSW joint caused the higher toughness property than the ATIG and LBW joints.

Evaluation of dissimilar joints properties of 5083-H12 and 6061-T6 aluminum alloys produced by tungsten inert gas and friction stir welding

2015 ◽  
Vol 231 (3) ◽  
pp. 297-308 ◽  
Author(s):  
Morteza Ghaffarpour ◽  
Mohammad Kazemi ◽  
Mohammad Javad Mohammadi Sefat ◽  
Ahmad Aziz ◽  
Kamran Dehghani
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Aluminum Alloys ◽  
Traverse Speed ◽  
Inert Gas ◽  
Dissimilar Joints ◽  
Friction Stir ◽  
Dissimilar Aluminum Alloys ◽  
The Difference ◽  
Welding Processes

In the present study, friction stir welding (FSW) and tungsten inert gas (TIG) techniques were used to join the dissimilar aluminum alloys of 5083-H12 and 6061-T6. The laboratory tests were designed using design of experiment (DOE) method. Variables for the FSW process were the rotational speed, traverse speed, shoulder diameter, and pin diameter. They changed in ranges of 700–2500 r/min, 25–400 mm/min, 10–14 mm, and 2–4 mm, respectively. In the case of TIG process, the variables were current intensity, traverse speed, and tilt angle. These parameters varied from 80 to 90 A, 200 to 400 mm/min, and 3° to 12°, respectively. The optimum amounts of parameters were obtained using response surface methodology (RSM). The RSM-based model was developed to predict ultimate tensile strength (UTS) of the welds produced. In FSW, the difference between predicted and measured UTS was about 1.28% and in TIG it was 1.78%. The good agreement between experimental and predicted results indicates the high accuracy of the developed model. Mechanical properties and also the microstructure of the welds were compared after optimizing both welding processes using RSM. The results showed that the welds produced by FSW indicated a considerably higher quality and also improved mechanical properties compared to TIG. Properties of the joints obtained by FSW in single-sided joints were more desirable. In the double-sided welds obtained by FSW these differences were of an even higher significance.

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.

scholarly journals Microstructure and Mechanical Properties of Friction Stir-Welded Dissimilar Joints of ZK60 and Mg-4.6Al-1.2Sn-0.7Zn Alloys

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 23
Author(s):  
Liangwen Xie ◽  
Xianyong Zhu ◽  
Yuexiang Fan ◽  
Weijia Sun ◽  
Peng Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Welded Joints ◽  
Gradual Increase ◽  
Tensile Fracture ◽  
Dissimilar Joints ◽  
Friction Stir ◽  
Base Materials ◽  
Transverse Tensile ◽  
Better Than

In order to clarify the microstructural evolution and the mechanical property of dissimilar friction stir-welded joints of ZK60 and Mg-4.6Al-1.2Sn-0.7Zn magnesium alloys, two types of arrangement with ZK60 at advancing side (AS) or retreating side (RS) were adopted. The macrostructure and the microstructure of the dissimilar welded joints were discussed, and the microhardness and the transverse tensile properties of the joints were measured. There are three stirring sub-zones with different compositions and two clear interfaces within the joints. Due to the effect of both the original grain size of base materials and the growth of recrystallized grains, in the stir zone (SZ), the grain size of ZK60 increased slightly, while the grain size of Mg-4.6Al-1.2Sn-0.7Zn decreased significantly. The dissolution of precipitates was gradually significant from RS to AS within the SZ due to the gradual increase in strain and heat. The grain refinement led to an increase in hardness, while the dissolution of precipitates resulted in a decrease in hardness. The performance of the joints obtained with ZK60 placed on the RS is slightly better than that of that on the AS. The tensile fracture of both joints occurred at the interface between SZ and the thermos-mechanical affected zone at the AS, and showed a quasi-dissociative fracture.

Numerical Simulation of the Effect of Shoulder Rotation on the Tensile Strength of FSW Dissimilar Joints of Aluminum Alloy

2020 ◽  
Vol 402 ◽  
pp. 90-99
Author(s):  
Riswanda ◽  
Akhyar ◽  
Sugianto ◽  
Harlian Kadir ◽  
Samsul Rizal
Keyword(s):  
Tensile Strength ◽  
Aluminum Alloys ◽  
Rotation Parameter ◽  
Maximum Temperature ◽  
Dissimilar Welding ◽  
Building Structures ◽  
Dissimilar Joints ◽  
Friction Stir ◽  
Dissimilar Weld ◽  
Weld Area

Dissimilar weld metal joints such as aluminum alloys 5083 and 6061-T6 are mostly found in the application of aircraft, railroad structures, ships, bridges, and oil platforms and building structures. However, dissimilar welding metal is relatively more difficult due to metallurgical differences and the thermophysical properties of two different materials. The purpose of this study is to study the effect of shoulder rotation variations on the Friction Stir Welding (FSW) process through numerical simulations on the mechanical properties of dissimilar weld joints between two series of aluminum alloys, and there are 5083 and 6061-T6. The FSW welding simulation process is conducted by butt joints type on 300 x 100 x 3 mm of both aluminum plates with weld distance is 300 mm. Shoulder rotation variations are carried out for this process include 1,200, 1,400 and 1,600 rpm. Results show maximum temperature distributions are 467 oC for 1,200 rpm, 499 °C for 1,400 rpm and 527 °C for 1,600 rpm, respectively. Maximum temperatures appear close to the liquid temperature of Al-6061-T6 and Al 5083 base metals, which is about 600 °C. Physical and mechanical analysis at 1,200 rpm (the rotation parameter) can be seen as the coarse weld beads on the microstructure, and the weld joint is still weak. The physical properties observed that coarse weld beads on microstructures, the tensile strength obtained 138 MPa at 1,200 rpm (the rotation parameter). The maximum hardness test occurred 47.98 (Kg/mm2 in averages) at 1,400 rpm. The tensile strength of the dissimilar FSW process is 151 MPa occurred at 1,600 rpm of shoulder rotation speed. While the fracture position occurs in the nugget weld area for all parameters and corresponds with the result of hardness tests, it shows that low hardness value for the whole weld area for all parameters.

The Influence of Ultrasound Enhancement during Friction Stir Welding of Aluminum to Steel

2018 ◽  
Vol 767 ◽  
pp. 351-359 ◽  
Author(s):  
Marco Thomä ◽  
Guntram Wagner ◽  
Benjamin Straß ◽  
Bernd Wolter ◽  
Sigrid Benfer ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Base Material ◽  
Dissimilar Materials ◽  
Dissimilar Joints ◽  
Power Ultrasound ◽  
Friction Stir ◽  
Wide Range ◽  
Steel Joints ◽  
Welding Processes ◽  
Ultrasound Enhancement

The innovative joining process of friction stir welding (FSW) offers a wide range of advantages for welding similar as well as dissimilar materials. Even for the field of poorly weldable material combinations like aluminum to steel with their strongly differing physical properties the method of FSW proved its capability for realizing dissimilar joints with tensile strengths up to more than 80 % of the aluminum base material. Trying to improve this value and other properties of the joints several approaches for hybrid friction stir welding processes were tested in the scientific community, whereas the ultrasound enhancement of FSW (USE-FSW) looked as one of the most promising reaching good results. To gain a deeper knowledge of the influence of the ultrasound on the friction stir welds different investigations were carried out in this paper. Therefore the method of USE-FSW was applied on two dissimilar aluminum/steel-joints with varying carbon content of the steel in this work. The material combinations AA6061/SAE1006 and AA6061/SAE1045 were welded successfully with and without additional power ultrasound. Afterwards a comparison between FSW-and USE-FSW-joints was carried out regarding the microstructure of the nugget and interface (IF) by light-microscopy as well as scanning electron microscopy. Furthermore the mechanical properties were characterized in a first step.

Friction stir welding of nuclear grade SA508Gr.3Cl.1 and SS304LN dissimilar steels

2018 ◽  
Vol 232 (21) ◽  
pp. 3814-3822 ◽  
Author(s):  
Ratnesh Kumar Raj Singh ◽  
Dinesh W Rathod ◽  
Sunil Pandey
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Friction Stir Welding ◽  
Charpy Impact ◽  
Hardness Measurement ◽  
Tensile Tests ◽  
Nuclear Grade ◽  
Friction Stir ◽  
Dissimilar Weld ◽  
Transverse Tensile

The present work has been carried out to justify the feasibility of dissimilar metal welds between nuclear grade SA508Gr.3Cl.1 ferritic steel and SS304LN stainless steel using friction stir welding. The evaluation has been made by analysing the metallurgical and mechanical properties of the friction stir welded dissimilar joint. Martensite formation and chemical variations in the weld nugget have been confirmed with optical microscopy, micro-hardness measurement and X-ray diffraction. The resultant chemistry variations owing to solid-state mixing on metallurgical and associated mechanical properties are significant. Transverse tensile tests and Charpy impact tests suggest the required strength of the joint. The tensile specimens were fractured from the SS304LN side, and similar sections of stainless steel have been torn with severe plastic deformation. The significant formation of martensite has not shown any adverse effect on the joint properties. The tool wear rate of tungsten carbide was high for this dissimilar weld.

Effect of Welding Processes on Mechanical and Microstructural Characteristics of DP780 Steel Welded Joints for the Automotive Industry

2020 ◽  
Vol 835 ◽  
pp. 101-107
Author(s):  
Khalid M. Hafez ◽  
Mohamed Mosalam Ghanem ◽  
Hamed A. Abdel-Aleem ◽  
Naglaa Fathy
Keyword(s):  
Laser Beam ◽  
Weld Metal ◽  
Automotive Industry ◽  
Welded Joints ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Laser Beam Welding ◽  
Metal Arc Welding ◽  
Welding Processes ◽  
Dp780 Steel

Arc welding processes are widely used in the automotive industry among other welding processes. Consequently, laser welding technology is being used instead of arc welding due to the rapid heating and cooling characteristics of the laser. In this study, empirical investigations and comparative study are held out on the arc and laser beam welded joints of DP780 dual-phase steel. Accordingly, weld joint microstructures, hardness distribution, and fatigue properties cross the butt-welded joints were investigated. The results showed that laser beam welding produces narrow fusion and heat-affected zones while gas metal arc welding produced wide welds with incomplete penetration. It was observed that the microstructure of the laser joint weld metal has mainly lath martensite in the ferritic matrix, while microstructure of gas metal arc weld metal relies upon filler type. Heat-affected zone in DP780 steel exhibit hardness softening in both laser beam welding and gas metal arc welding due to martensite tempering, a wider softening region was clearly observed in heat-affected zone welded by gas metal arc welding than laser beam welding. Generally, fatigue ratio, fatigue limit and fatigue life of the welded joints were improved by using laser welding.

Sign in / Sign up

Export Citation Format

Share Document