Investigation of Interfacial Layer for Friction Stir Welded AA7075-T6 Aluminum to DP1180 Steel Joints

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Zhi-li Hu ◽  
Hai-yang Yu ◽  
Qiu Pang
Keyword(s):  
Mechanical Performance ◽  
High Strength ◽  
Interfacial Microstructure ◽  
Galvanized Steel ◽  
X Ray Diffraction ◽  
Interfacial Layers ◽  
Friction Stir ◽  
Metallurgical Bonding ◽  
Formation And Evolution ◽  
Steel Joints

Abstract Interfacial layers greatly influence the performance of steel–aluminum friction stir welding (FSW) joints, and understanding the formation and evolution of intermetallic compounds (IMC) can help improve the mechanical properties of the welds. In this study, FSW was used to join DP 1180 high-strength steel to 7075 Al at different welding speeds. The effect of the galvanized layer on the IMC formation and evolution, and the mechanical performance of the steel–Al FSW joints were investigated. It was found that the galvanized steel–Al joints were formed only by metallurgical bonding, a continuous IMC layer composed of FeAl, Fe3Al, and Al–Zn eutectic developed at the joint interfaces. Joints were mechanically and metallurgically bonded in the non-galvanized steel, and a 3 µm thick IMC layer consisting of FeAl existed only in the stir zone (SZ). IMC layer formation was predicted according to thermodynamic principles, which is consistent with the interfacial microstructure evolution identified by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Shear tensile test results showed that the galvanized layer can effectively improve the metallurgical bonding strength of the steel–Al joints, and the optimum tensile properties were found in galvanized steel–Al joints.

scholarly journals Microstructure and Mechanical Properties of Galvanized-45 Steel/AZ91D Bimetallic Material by Liquid-Solid Compound Casting

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1651 ◽  
Author(s):  
Jun Cheng ◽  
Jian-hua Zhao ◽  
Jin-yong Zhang ◽  
Yu Guo ◽  
Ke He ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Corrosion Current ◽  
Eutectic Structure ◽  
Galvanized Steel ◽  
X Ray Diffraction ◽  
Solid Compound ◽  
Metallurgical Bonding ◽  
Compound Casting ◽  
Bimetallic Material ◽  
Bimetallic Materials

A connection between hot-dip galvanized 45 steel and AZ91D was achieved by liquid-solid compound casting to achieve one material with a better mechanical performance and a light weight. The microstructure and properties of galvanized-steel/AZ91D bimetallic materials were investigated in this study. A scanning electron microscopy (SEM), an energy dispersive spectroscopy (EDS), and an X-ray diffraction (XRD) were applied to analyze the microstructure evolution and formation mechanism of the galvanized 45 steel/AZ91D interface zone which could be divided into three layers. Among three different layers, the layer close to AZ91D was composed of α-Mg and an eutectic structure (α-Mg + MgZn). The intermediate layer was comprised of an eutectic structure (α-Mg + MgZn), and the layer adjacent to 45 steel consisted of α-Mg and FeAl3. Furthermore, galvanized-45 steel/AZ91D bimetallic material had better shear strength than the bare-45 steel/AZ91D metallic material which can indicate that owing to the formation of metallurgical bonding, the adhesive strength of galvanized-steel and AZ91D was improved to 11.81 MPa. In addition, the fact that corrosion potential increased from −1.493 V to −1.143 V and corrosion current density changed from 3.015 × 10−5 A/cm2 to 1.34 × 10−7 A/cm2 implied that the corrosion resistance of galvanized-steel/AZ91D was much better than AZ91D.

scholarly journals Evaluation of Biomedical Ti/ZrO2 Joint Brazed with Pure Au Filler: Microstructure and Mechanical Properties

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 526
Author(s):  
Yuzhen Lei ◽  
Hong Bian ◽  
Wei Fu ◽  
Xiaoguo Song ◽  
Jicai Feng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Energy Dispersive Spectrometry ◽  
Filler Metal ◽  
Interfacial Microstructure ◽  
Holding Time ◽  
X Ray Diffraction ◽  
X Ray ◽  
Medical Products ◽  
Metallurgical Bonding ◽  
Brazed Joints

Titanium and zirconia (ZrO2) ceramics are widely used in biomedical fields. This study aims to achieve reliable brazed joints of titanium/ZrO2 using biocompatible Au filler for implantable medical products. The effects of brazing temperature and holding time on the interfacial microstructures and mechanical properties of titanium/Au/ZrO2 joints were fully investigated by scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and X-ray diffraction (XRD). The results indicated that the typical interfacial microstructure of the titanium/Au/ZrO2 joint was titanium/Ti3Au layer/TiAu layer/TiAu2 layer/TiAu4 layer/TiO layer/ZrO2 ceramic. With an increasing brazing temperature or holding time, the thickness of the Ti3Au + TiAu + TiAu2 layer increased gradually. The growth of the TiO layer was observed, which promoted metallurgical bonding between the filler metal and ZrO2 ceramic. The optimal shear strength of ~35.0 MPa was obtained at 1150 °C for 10 min. SEM characterization revealed that cracks initiated and propagated along the interface of TiAu2 and TiAu4 reaction layers.

scholarly journals Investigation of Interfacial Layer for Friction Stir Scribe Welded Aluminum to Steel Joints

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Kaifeng Wang ◽  
Piyush Upadhyay ◽  
Yuxiang Wang ◽  
Jingjing Li ◽  
Xin Sun ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Driving Force ◽  
Bond Formation ◽  
Welding Process ◽  
High Strength ◽  
Bimaterial Interface ◽  
Joint Interface ◽  
Friction Stir ◽  
Transmission Electron ◽  
Steel Joints

Friction stir scribe (FSS) welding as a recent derivative of friction stir welding (FSW) has been successfully used to fabricate a linear joint between automotive Al and steel sheets. It has been established that FSS welding generates a hook-like structure at the bimaterial interface. Beyond the hook-like structure, there is a lack of fundamental understanding on the bond formation mechanism during this newly developed FSS welding process. In this paper, the microstructures and phases at the joint interface of FSS welded Al to ultra-high-strength steel were studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that both mechanical interlocking and interfacial bonding occurred simultaneously during the FSS welding process. Based on SEM observations, a higher diffusion driving force in the advancing side was found compared to the retreating side and the scribe swept zone, and thermally activated diffusion was the primary driving force for the interfacial bond formation in the scribe swept region. The TEM energy-dispersive X-ray spectroscopy (EDXS) revealed that a thin intermetallic compound (IMC) layer was formed through the interface, where the thickness of this layer gradually decreased from the advancing side to the retreating side owing to different material plastic deformation and heat generations. In addition, the diffraction pattern (or one-dimensional fast Fourier transform (FFT) pattern) revealed that the IMC layer was composed of Fe2Al5 or Fe4Al13 with a Fe/Al solid solution depending on the weld regions.

Process Window for Friction Stir Lap Welding of Aluminum Alloy 6061

2014 ◽  
Vol 783-786 ◽  
pp. 2839-2844
Author(s):  
Simon Larose ◽  
Maxime Guérin ◽  
Priti Wanjara
Keyword(s):  
Aluminum Alloy ◽  
Mechanical Performance ◽  
High Strength ◽  
Butt Joint ◽  
Process Window ◽  
Tool Geometry ◽  
Transportation Industry ◽  
Friction Stir ◽  
Planar Surfaces ◽  
Lap Welding

Precipitation-hardenable 6xxx series aluminum alloys are incorporated in many structural components with due consideration of their good combination of properties including a relatively high strength, outstanding extrudability and excellent corrosion resistance. Accordingly, AA6061 has been identified as a very good candidate material for structural lightweighting of transportation vehicles. However, the weldability of aluminum alloy (AA) 6061 by means of conventional technologies such as GMAW and GTAW methods is limited by sensitivity to solidification cracking. In this respect, friction stir welding (FSW) presents a tremendous potential for assembly of aluminum structures for the transportation industry due to the low heat involved that can mitigate crack formation and, thus, translate into improved mechanical performance of the assembly. In this work, FSW of 3.18 mm thick AA6061-T6 sheets in the lap joint configuration was investigated. This configuration is considered to be more challenging for assembly by FSW than the butt joint type due to the orientation of the interface with respect to the welding tools and the necessity to break the oxide layer on two aluminium alloy planar surfaces. Weld trials were performed to examine the influence of the FSW tool geometry and process parameters on the welding defects, microstructure, hardness and bend performance. Unacceptable material expulsion and/or significant thinning in one of the two overlapped sheets were produced under most conditions. A set of FSW tool geometries leading to a viable process operational window under which the risk of defects could be mitigated and/or eliminated was identified in this study.

scholarly journals Fatigue Strength Improvement Due to Alloying Steel Weld Toes With WC-Tool Constituent Elements Through Friction Stir Processing

2021 ◽  
Author(s):  
Hajime Yamamoto ◽  
Shodai Koga ◽  
Kazuhiro Ito ◽  
Yoshiki Mikami
Keyword(s):  
Fatigue Strength ◽  
Rotational Speed ◽  
Hsla Steel ◽  
High Strength ◽  
Weld Toes ◽  
Tool Rotational Speed ◽  
Friction Stir ◽  
Steel Layer ◽  
Constituent Elements ◽  
Steel Joints

Abstract Friction stir processing (FSP) enables surface modifications using a rotational tool and can likely be applied as a new post-weld treatment for improving fatigue strength. When applying FSP to high strength materials, tool wear occurring at the interface between the tool tip and the topmost steel layer has been regarded as an unavoidable issue and is related to the tool rotational speed. The present study investigated the relationship between the tool rotational speed and fatigue strength of arc-welded high-strength low-alloy (HSLA) steel joints with weld toes subjected to FSP using a spherical-tip WC tool. FSP was conducted on the weld toe of HSLA steel joints with various tool rotational speeds. Tool wear increased with increase in tool rotational speed, and consequently contents of constituent elements of the WC tool increased in the topmost steel layer of weld toes, leading to large increase of fatigue strength. One reason for the increase with tool rotational speed is significant increase of solid solution hardening due to supersaturated W and C in the topmost steel layer consisting of martensite laths. The hardened topmost steel layer prevented fatigue crack initiation, and the increased fatigue strength depended on the contents of supersaturated W and C.

scholarly journals Corrosion Study of Galvanized Ultra High Strength Steel Reinforced Overhead Transmission Conductors

2018 ◽  
Vol 7 (3.18) ◽  
pp. 83
Author(s):  
Amir Azam Khan ◽  
David Bong Boon Liang ◽  
Andrew Ragai Henry Rigit ◽  
Lim Soh Fong ◽  
Al-Khalid Othman ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Zinc Coating ◽  
High Strength ◽  
Weather Conditions ◽  
The State ◽  
Strategic Decision ◽  
Galvanized Steel ◽  
X Rays ◽  
X Ray Diffraction ◽  
Structure Changes

Overhead high voltage transmission conductors used worldwide are produced in several configurations. A multi-strand conductor of the type ACSR330 is typically used for 275 kV overhead transmission lines. The conductor is composed of 7 inner strands of Ultra High Strength Galvanized Steel for the mechanical support of the conductor and 26 strands of high conductivity Aluminum wires meant for power transfer over long distances. During the use, weather conditions and power fluctuations tend to degrade the properties of these conductors. In the present work, study of the state of galvanization and oxidation of an ACSR330 conductor is undertaken with a view to understand the effectiveness of the loss in corrosion protection and changes in the zinc coating on the galvanized steel strands after use for 25 to 30 years. The Scanning Electron Microscopy (SEM), X Ray Diffraction (XRD) and Energy Dispersive Analysis through X rays (EDAX) provide a very useful insight into the state of the conductor and gives important information to the strategic decision maker, whether or not to replace the conductor. It was observed in the present study that the zinc coating diffuses inside the steel strand under temperature and time effect. This unique study on the used conductors also reveals that the morphology of the coating and its interface structure changes significantly compared to an unused conductor of the same age.    

The Effect of Rotation Speed and Dwell Time on the Zn Distribution of the Dissimilar Metals Friction Stir Spot Welded between Aluminum Alloy and Galvanized Steel

2020 ◽  
Vol 402 ◽  
pp. 61-66
Author(s):  
Zuhri Nurisna ◽  
Ardian Wicahyo Nugroho ◽  
Nurul Muhayat ◽  
Triyono
Keyword(s):  
Aluminum Alloy ◽  
Dwell Time ◽  
Rotation Speed ◽  
High Strength ◽  
Galvanized Steel ◽  
Dissimilar Metals ◽  
Friction Stir ◽  
Zn Distribution ◽  
Tool Rotation ◽  
Spot Welded

Zink (Zn) in galvanized steel has a positive effect on improving the properties of the dissimilar metals weld between aluminum alloy and galvanized steel. Its distribution is important to be evaluated. The aim of this work is to investigate the effect of rotation speed and dwell time on the Zn distribution of the friction-stir-spot-welded (FSSW) dissimilar metals between aluminum alloy and galvanized steel. FSSW was subjected to 3 mm thick of Aluminum and 1 mm thick of galvanized steel with a plunge depth of 2.7 mm and a penetration rate of 0.9 mm/s. High strength steel (HSS) with a hardness of 70 HRC and a diameter of 12 mm was used as FSSW tool. Tool rotation was varied at 1000 rpm, 1200 rpm, 1600 rpm, and 2000 rpm while dwell time was varied of 3 s, 5 s, and 7 s. A Scanning Electron Microscope (SEM) was performed to reveal the Zn distribution after cross-sectioning, polishing, and etching. During the FSSW process, the heat was generated, Zn softened, and carried away by the materials flow due to tool rotation. Both the rotation speed and the dwell time played a role in increasing the distance and the amount of Zn flow in the welded zone. FSSW process in dissimilar metals between aluminum and galvanized steel formed the unique pattern of Zn distribution.

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