scholarly journals High strength and ductility of friction-stir-welded steel joints due to mechanically stabilized metastable austenite

2014 ◽  
Vol 70 ◽  
pp. 39-42 ◽  
Author(s):  
Hidetoshi Fujii ◽  
Rintaro Ueji ◽  
Yoshiaki Morisada ◽  
Hiroyasu Tanigawa
Keyword(s):  
High Strength ◽  
Metastable Austenite ◽  
Welded Steel ◽  
Friction Stir ◽  
Mechanically Stabilized ◽  
Steel Joints ◽  
Strength And Ductility

Fatigue Behaviour of Friction Stir Welded Steel Joints

2014 ◽  
Vol 891-892 ◽  
pp. 1488-1493 ◽  
Author(s):  
José Azevedo ◽  
Virgínia Infante ◽  
Luisa Quintino ◽  
Jorge dos Santos
Keyword(s):  
Base Material ◽  
Welding Process ◽  
Steel Structures ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Welded Steel ◽  
Shipbuilding Industry ◽  
Friction Stir ◽  
Steel Joints

The development and application of friction stir welding (FSW) technology in steel structures in the shipbuilding industry provide an effective tool of achieving superior joint integrity especially where reliability and damage tolerance are of major concerns. Since the shipbuilding components are inevitably subjected to dynamic or cyclic stresses in services, the fatigue properties of the friction stir welded joints must be properly evaluated to ensure the safety and longevity. This research intends to fulfill a clear knowledge gap that exists nowadays and, as such, it is dedicated to the study of welded steel shipbuilding joints in GL-A36 steel, with 4 mm thick. The fatigue resistance of base material and four plates in as-welded condition (using several different parameters, tools and pre-welding conditions) were investigated. The joints culminate globally with defect-free welds, from which tensile, microhardness, and fatigue analyses were performed. The fatigue tests were carried out with a constant amplitude loading, a stress ratio of R=0.1 and frequency between 100 and 120 Hz. The experimental results show the quality of the welding process applied to steel GL-A36 which is reflected in the mechanical properties of joints tested.

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.

Achieving high strength and ductility in double-sided friction stir processing 7050-T7451 aluminum alloy

2017 ◽  
Vol 707 ◽  
pp. 193-198 ◽  
Author(s):  
Wenjing Yang ◽  
Hua Ding ◽  
Yongliang Mu ◽  
Jizhong Li ◽  
Wenjing Zhang
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Processing ◽  
High Strength ◽  
Friction Stir ◽  
Strength And Ductility

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.

Friction stir extrusion for fabricating Mg-RE alloys with high strength and ductility

2021 ◽  
Vol 289 ◽  
pp. 129414
Author(s):  
Junchen Li ◽  
Xiangchen Meng ◽  
Yulong Li ◽  
Long Wan ◽  
Yongxian Huang
Keyword(s):  
High Strength ◽  
Friction Stir ◽  
Friction Stir Extrusion ◽  
Strength And Ductility

scholarly journals Weldability of high strength steels in wet welding conditions

2013 ◽  
Vol 20 (2) ◽  
pp. 67-73 ◽  
Author(s):  
Dariusz Fydrych ◽  
Jerzy Łabanowski ◽  
Grzegorz Rogalski
Keyword(s):  
High Strength Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Cold Cracking ◽  
High Susceptibility ◽  
Welded Steel ◽  
Underwater Wet Welding ◽  
Formation Of Cracks ◽  
Steel Joints ◽  
Welding Technique

Abstract In this paper are characterized problems of high strength steel weldability in underwater wet welding conditions. Water as a welding environment intensifies action of unfavourable factors which influence susceptibility to cold cracking of welded steel joints. The susceptibility to cold cracking of S355J2G3 steel and S500M steel in wet conditions was experimentally estimated (by using Tekken test). It was concluded that the steels in question are characterized by a high susceptibility to formation of cracks in welds. Usefulness of the proposed Temper Bead Welding technique (TBW) was experimentally verified as a method for improving weldability of the steels in the analyzed conditions.

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.

Mechanical properties of friction stir welded St 37 and St 44 steel joints

2018 ◽  
Vol 60 (12) ◽  
pp. 1163-1170 ◽  
Author(s):  
Tevfik Küçükömeroğlu ◽  
Semih Mahmut Aktarer ◽  
Güven İpekoğlu ◽  
Gürel Çam
Keyword(s):  
Mechanical Properties ◽  
Friction Stir ◽  
Steel Joints
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