scholarly journals Can High-Entropy Interlayers Develop Intermetallic-Free Welded Joints of Dissimilar Metals?

Eng ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 183-187
Author(s):  
Owais Ahmed Waseem
Keyword(s):  
Intermetallic Compounds ◽  
Diffusion Layer ◽  
Welded Joints ◽  
Research Area ◽  
Fusion Welding ◽  
Dissimilar Metals ◽  
Catastrophic Failure ◽  
High Entropy ◽  
Steel Joints ◽  
Zr Alloy

The joining of two chemically dissimilar metals is a challenge due to the formation of hard and brittle intermetallic compounds (IMCs) in the diffusion layer. The joining of steel/Fe with aluminum (Al) and zirconium (Zr) alloy is particularly important for the automobile and nuclear industries, respectively. The Al–steel and Zr–steel joints produced by conventional fusion welding exhibit IMCs. The IMCs can enhance brittleness and cause catastrophic failure. This concept paper presents a novel idea of suppressing IMCs in welded joints using a high-entropy interlayer (HEI). It also discusses the potential candidates for HEIs and inspires research to exploit this new and promising research area.

A Materials and Mechanical Characterization of Friction Stir Welded Aluminum-Steel Joints with Respect to Intermetallic Compounds Content

2021 ◽  
Vol 878 ◽  
pp. 104-112
Author(s):  
Zeina G. El Chlouk ◽  
Mutasem A. Shehadeh ◽  
Ramsey F. Hamade
Keyword(s):  
Intermetallic Compounds ◽  
Mechanical Characterization ◽  
Dissimilar Materials ◽  
Mechanical Deformation ◽  
Intermetallic Phases ◽  
Fusion Welding ◽  
Friction Stir ◽  
Full Characterization ◽  
Steel Joints

In order to weld dissimilar materials with dramatically different properties such as aluminum and steel, friction stir welding (FSW) offers many advantages over conventional fusion welding techniques. However, producing strong and durable FSW joints requires full characterization of these joints including metallurgical and mechanical characterization. In this work, many process parameters and two different tools are put to test and the resulting FSW joints are characterized. Their mechanical strength is investigated in tension with respect to intermetallic compounds content analyzed using SEM coupled to EDX. The soundest 2mm thick joints recovered 55% of the strength of the original un-welded metal whereas in the case of the 3mm thick joints 47% of the strength could only be recovered in the best case. It was revealed that as the content in intermetallic compound increases the strength of the joints decreases. Additionally, it was found that the higher the mechanical deformation, the more these compounds are abundant; in other words, intermetallic compounds were largely found in the middle and bottom sections of the 3mm thick samples which is where the threads of the pin do most of their work. The compositions of these intermetallic phases along the abutting surfaces is also proposed based on the elemental composition of Fe and Al as detected by the scanning electron microscopy.

Friction Welding of Titanium to 304 Stainless Steel with Electroplated Nickel Interlayer

2012 ◽  
Vol 710 ◽  
pp. 620-625 ◽  
Author(s):  
Muralimohan Cheepu ◽  
V. Muthupandi ◽  
S. Loganathan
Keyword(s):  
Stainless Steel ◽  
Welded Joints ◽  
Friction Welding ◽  
Pure Titanium ◽  
Weld Interface ◽  
Fusion Welding ◽  
304 Stainless Steel ◽  
Dissimilar Metals ◽  
Fracture Surfaces ◽  
Welding Processes

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.

Estimation of Some Mechanical Properties for Similar & Dissimilar Welded Joints

2014 ◽  
Vol 2 (1) ◽  
pp. 59-76
Author(s):  
Abdullah Daie'e Assi
Keyword(s):  
Stainless Steel ◽  
Carbon Steel ◽  
Austenitic Stainless Steel ◽  
Base Metal ◽  
Welded Joints ◽  
Plate Thickness ◽  
Low Carbon Steel ◽  
Dissimilar Metals ◽  
Low Carbon ◽  
Steel Type

This research deals with the choice of the suitable filler metal to weld the similar and dissimilar metals (Low carbon steel type A516 & Austenitic stainless steel type 316L) under constant conditions such as, plate thickness (6 mm), voltage (78 v), current (120 A), straight polarity. This research deals with three major parts. The first parts Four types of electrodes were used for welding of dissimilar metals (C.St A516 And St.St 316L) two from mild steel (E7018, E6013) and other two from austenitic stainless steel (E309L, E308L) various inspection were carried out include (Visual T., X-ray T., δ- Ferrite phase T., and Microstructures T.) and mechanical testing include (tensile T., bending T. and micro hardness T.) The second parts done by used the same parameters to welding similar metals from (C.St A516) Or (St.St 316L). The third parts deals with welding of dissimilar weldments (C.St And St.St) by two processes, gas tungsten are welding (GTAW) and shielded metal are welding (SMAW).        The results indicated that the spread of carbon from low carbon steel to the welding zone in the case of welding stainless steel elect pole (E309L) led to Configuration Carbides and then high hardness the link to high values ​​compared with the base metal. In most similar weldments showed hardness of the welding area is  higher than the hardness of the base metal. The electrode (E309L) is the most suitable to welding dissimilar metals from (C.St A516 With St.St 316L). The results also showed that the method of welding (GTAW) were better than the method of welding (SMAW) in dissimilar welded joints (St.St 316L with C.St A516) in terms of irregular shape and integrity of the welding defects, as well as characterized this weldments the high-lift and resistance ductility good when using the welding conditions are similar.

scholarly journals Effect of weld metal composition on impact toughness properties of shielded metal arc welded ultra-high hard armor steel joints

2020 ◽  
Vol 29 (1) ◽  
pp. 186-194
Author(s):  
V. Balaguru ◽  
Visvalingam Balasubramanian ◽  
P. Sivakumar
Keyword(s):  
Impact Toughness ◽  
Weld Metal ◽  
Welded Joints ◽  
Weight Ratio ◽  
High Hardness ◽  
High Strength ◽  
Solidification Mode ◽  
Austenitic Phase ◽  
Ferrite Number ◽  
Steel Joints

AbstractNowadays, ultra-high hard armor (UHA) steels are employed in armor tracked vehicle (ATV) construction because of their high hardness, high strength to weight ratio, and excellent toughness. UHA steels are usually welded using austenitic stainless steel (ASS) welding consumables, to avoid hydrogen-induced cracking (HIC). The use of ASS consumables to weld the above steel was the only available remedy because of higher solubility of hydrogen in the austenitic phase. In this investigation, an attempt was made to investigate the effect of ASS consumables (with different Creq/Nieq ratio) on solidification mode, impact toughness and microstructural characteristics of shielded metal arc (SMA) welded UHA steel joints. The welded joints were characterised based on impact toughness properties, hardness, and microstructural features. As the ferrite number increases with an increase in Creq/Nieq ratio result in different solidification mode (A, FA, F). It is also found that ferrite number of weld metal has appreciable influence on impact toughness and has inversely proportional relationship with impact toughness of the welded joints.

Structure of laser welded joints of multicomponent high-entropy alloy of Nb–Cr–Ti–Al–Zr system

2021 ◽  
Vol 2021 (6) ◽  
pp. 26-31
Author(s):  
V.D. Shelyagin ◽  
◽  
A.V. Bernatskyi ◽  
O.V. Siora ◽  
V.I. Bondareva ◽  
...  
Keyword(s):  
Welded Joints ◽  
High Entropy Alloy ◽  
High Entropy

scholarly journals Mechanical and Thermal Conductivity Properties of Enhanced Phases in Mg-Zn-Zr System from First Principles

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2010
Author(s):  
Shuo Wang ◽  
Yuhong Zhao ◽  
Huijun Guo ◽  
Feifei Lan ◽  
Hua Hou
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Intermetallic Compounds ◽  
Elastic Constants ◽  
First Principles ◽  
Strengthening Phases ◽  
Zr Alloy ◽  
Zr Alloys

In this paper, the mechanical properties and minimum thermal conductivity of ZnZr, Zn2Zr, Zn2Zr3, and MgZn2 are calculated from first principles. The results show that the considered Zn-Zr intermetallic compounds are effective strengthening phases compared to MgZn2 based on the calculated elastic constants and polycrystalline bulk modulus B, shear modulus G, and Young’s modulus E. Meanwhile, the strong Zn-Zr ionic bondings in ZnZr, Zn2Zr, and Zn2Zr3 alloys lead to the characteristics of a higher modulus but lower ductility than the MgZn2 alloy. The minimum thermal conductivity of ZnZr, Zn2Zr, Zn2Zr3, and MgZn2 is 0.48, 0.67, 0.68, and 0.49 W m−1 K−1, respectively, indicating that the thermal conductivity of the Mg-Zn-Zr alloy could be improved as the precipitation of Zn atoms from the α-Mg matrix to form the considered Zn-Zr binary alloys. Based on the analysis of the directional dependence of the minimum thermal conductivity, the minimum thermal conductivity in the direction of [110] can be identified as a crucial short limit for the considered Zn-Zr intermetallic compounds in Mg-Zn-Zr alloys.

scholarly journals The Effects of In-Process Cooling during Friction Stir Welding of 7475 Aluminium Alloy

2021 ◽  
Vol 50 (9) ◽  
pp. 2743-2754
Author(s):  
Ashish Jacob ◽  
Sachin Maheshwari ◽  
Arshad Noor Siddiquee ◽  
Abdulrahman Al-Ahmari ◽  
Mustufa Haider Abidi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Welded Joints ◽  
Positive Impact ◽  
Welding Process ◽  
Fusion Welding ◽  
Friction Stir ◽  
Cooling Conditions ◽  
Zero Degree ◽  
Welding Technique

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.

Solid State Amorphization and Alloy Parameters for High Entropy Alloys

2021 ◽  
Vol 1016 ◽  
pp. 990-996
Author(s):  
Takeshi Nagase
Keyword(s):  
Solid Solution ◽  
Solid State ◽  
Intermetallic Compounds ◽  
Electron Irradiation ◽  
Fast Electron ◽  
High Entropy Alloy ◽  
Solid Solution Formation ◽  
High Entropy ◽  
Solution Formation ◽  
State Amorphization

Fast electron irradiation can induce the solid-state amorphization (SSA) of many intermetallic compounds. The occurrence of SSA stimulated by fast electron irradiation was found in the Al0.5TiZrPdCuNi high-entropy alloy (HEA). The relationship between the occurrence of SSA in intermetallic compounds under fast electron irradiation and the empirical alloy parameters for predicting the solid-solution-formation tendency in HEAs was discussed. The occurrence of SSA in intermetallic compounds was hardly predicted, only by the alloy parameters of δ or ΔHmix, which have been widely used for predicting solid-solution formation in HEAs. All intermetallic compounds with ΔHmix ≤ -35 kJ/mol and those with δ ≥ 12.5 exhibit the occurrence of SSA. This implies that the intermetallic compounds with a largely negative ΔHmix value and a largely positive δ parameter are favorable for the occurrence of SSA.

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