Influence of Process Heat Input on Static and Dynamic Properties of Friction Stir Welded 3mm Ti6Al4V Alloy

2014 ◽  
Vol 1019 ◽  
pp. 287-293
Author(s):  
Peter Madindwa Mashinini ◽  
D.G. Hattingh ◽  
Hannalie Lombard
Keyword(s):  
Heat Input ◽  
Dynamic Properties ◽  
Travel Speed ◽  
Ti6al4v Alloy ◽  
Tool Geometry ◽  
Original Material ◽  
Friction Stir ◽  
Tool Shoulder ◽  
The Relationship ◽  
Joint Integrity

This paper presents an investigation on the influence of varying heat input during friction stir welding of Ti6Al4V alloy, with respect to static and dynamic joint integrity. Weld heat input was controlled by varying the rotational-and tool travel speed. In the absences of large defects the welded samples failed predominately in the parent plate, while percentage elongation for all welds was lower than that of the original material. To quantify the influence of joint geometry on dynamic joint integrity, the test samples were categorised into “as-welded” and “polished” conditions for ease of comparison. Welds done at medium heat input exhibited improved fatigue strength in both conditions, while crack initiation sites for the as-welded condition was predominantly from tool shoulder marks whereas the polished sample initiation sites could be mainly linked to subsurface defects in the weld nugget. The relationship between welding tool geometry, weld defects and-process parameters is also discussed in an attempt to identify interrelationships that could be linked to joint integrity.

Features of structure formation processes in AA2024 alloy joints formed by the friction stir welding with bobbin tool

2021 ◽  
Vol 23 (2) ◽  
pp. 98-115
Author(s):  
Alexey Ivanov ◽  
◽  
Valery Rubtsov ◽  
Andrey Chumaevskii ◽  
Kseniya Osipovich ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Structure Formation ◽  
Welded Joints ◽  
Heat Input ◽  
Welded Joint ◽  
Welding Process ◽  
Tool Material ◽  
Travel Speed ◽  
Material System ◽  
Friction Stir

Introduction. One of friction stir welding types is the bobbin friction stir welding (BFSW) process, which allows to obtain welded joints in various configurations without using a substrate and axial embedding force, as well as to reduce heat loss and temperature gradient across the welded material thickness. This makes the BFSW process effective for welding aluminum alloys, which properties are determined by their structural-phase state. According to research data, the temperature and strain rate of the welded material have some value intervals in which strong defect-free joints are formed. At the same time, much less attention has been paid to the mechanisms of structure formation in the BFSW process. Therefore, to solve the problem of obtaining defect-free and strong welded joints by BFSW, an extended understanding of the basic mechanisms of structure formation in the welding process is required. The aim of this work is to research the mechanisms of structure formation in welded joint of AA2024 alloy obtained by bobbin tool friction stir welding with variation of the welding speed. Results and discussion. Weld formation conditions during BFSW process are determined by heat input into a welded material, its fragmentation and plastic flow around the welding tool, which depend on the ratio of tool rotation speed and tool travel speed. Mechanisms of joint formation are based on a combination of equally important processes of adhesive interaction in “tool-material” system and extrusion of metal into the region behind the welding tool. Combined with heat dissipation conditions and the configuration of the “tool-material” system, this leads to material extrusion from a welded joint and its decompaction. This results in formation of extended defects. Increasing in tool travel speed reduce the specific heat input, but in case of extended joints welding an amount of heat released in joint increases because of specific heat removal conditions. As a result, the conditions of adhesion interaction and extrusion processes change, which leads either to the growth of existing defects or to the formation of new ones. Taking into account the complexity of mechanisms of structure formation in joint obtained by BFSW, an obtaining of defect-free joints implies a necessary usage of various nondestructive testing methods in combination with an adaptive control of technological parameters directly in course of a welding process.

scholarly journals Analysis of Tools used in Friction Stir Welding process

2018 ◽  
Vol 8 (6) ◽  
Author(s):  
Akshansh Mishra ◽  
Adarsh Tiwari ◽  
Mayank Kumar Shukla ◽  
A. Razal Rose
Keyword(s):  
Friction Stir Welding ◽  
Critical Role ◽  
Base Material ◽  
Welding Process ◽  
Tool Geometry ◽  
Work Piece ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Tool Pin ◽  
Joining Process

A relatively new joining process, friction stir welding (FSW) produces no fumes; uses no filler material; and can join aluminium alloys, copper, magnesium, zinc, steels, and titanium. FSW sometimes produces a weld that is stronger than the base material. The tool geometry plays a critical role in material flow and governs the transverse rate at which FSW can be conducted. The tool serves three primary functions, i.e., (a) heating of the work piece, (b) movement of material to produce the joint, and (c) containment of the hot metal beneath the tool shoulder. Heating is created within the work piece by friction between both the rotating tool pin and shoulder and by severe plastic deformation of the work.

Experimental Analysis of Residual Stress in Friction Stir Processed Cast AlSi9Mg Aluminium Alloy

2016 ◽  
Vol 682 ◽  
pp. 18-23 ◽  
Author(s):  
Marek Stanisław Węglowski ◽  
Piotr Sedek ◽  
Carter Hamilton
Keyword(s):  
Residual Stress ◽  
Aluminium Alloy ◽  
Rotational Speed ◽  
Parent Material ◽  
Tool Geometry ◽  
Friction Stir ◽  
Compressive Stresses ◽  
Longitudinal Residual Stress ◽  
Stress Profiles ◽  
The Relationship

The relationship between friction stir processing (FSP) parameters and longitudinal residual stress profiles in modified cast aluminium alloy AlSi9Mg is presented. The influence of tool geometry, rotational speed and the number of processing passes were analysed. To experimentally measure residual stress, the trepanation method was adopted. The results indicated that an increase in the rotational speed caused an increase in the residual stress. Also, the Triflute tool promoted a higher level of residual stress than a conventional FSP tool. The region around the FSP bead was characterised by tensile residual stress fields that were balanced by compressive stresses in the parent material. A higher residual stress is observed on the advancing side than on the retreating side. An increase in the number of processing passes increased the level of residual stress in the modified material.

Material flow and mechanical properties of friction stir welded Al-Mg-Si alloy: Role of concentric circles shoulder with non-circular pins

2021 ◽  
pp. 095440622198939
Author(s):  
Krishna Kishore Mugada ◽  
Kumar Adepu
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Heat Input ◽  
Material Flow ◽  
Process Conditions ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Average Hardness ◽  
Concentric Circles

Understanding the material flow in friction stir welding (FSW) is one of the challenging aspects for producing defect free and quality welds. The material flow is majorly governed by the tool shoulder/pin geometries and process conditions. In the present study, concentric circles shoulder shape with various polygonal pin designs are selected, and their influence on material flow and mechanical properties in Al 6082 friction stir welds is addressed. Material flow is studied by inserting the markers before welding and subsequent analysis of deformed marker material by radiography and macrostructure after welding. The outcome shows the welds with square pin design facilitated a constant stable force, and hexagonal pin design facilitated a decreasing behavior of force with reference to welding length/time. The heat input is increasing from triangular pin to hexagonal pin and is maximum for welds with hexagonal pins (973 kJ/mm). Further, welds with hexagonal pins (TCC)HEX tool facilitated higher mechanical properties of strength (187 MPa) and average hardness (79 HV) at the stir zone.

On Increasing Productivity of Micro-Friction Stir Welding With Aid of Tool Shoulder Micro-Features

2019 ◽  
Author(s):  
Shuja Ahmed ◽  
Akash Mukhopadhyay ◽  
Probir Saha
Keyword(s):  
Friction Stir Welding ◽  
Tensile Property ◽  
Surface Finish ◽  
Travel Speed ◽  
Tool Rotational Speed ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Spiral Shape ◽  
Micro Features ◽  
Alloy 6061

Abstract Prior investigations on micro-friction stir welding (micro-FSW) of 0.5 mm thick aluminium alloy 6061-T6 sheets have shown that increasing the tool travel speed above 200 mm/min, at a fixed tool rotational speed (1900 rpm) and shoulder penetration (0.10 mm), results in lack of penetration defect in the welds. This limits the production rate and may distract the interest of industries which aim at utilizing micro-FSW for joining of micro-mechanical components. The present work investigates the utilization of micro-features on tool shoulder face to solve this issue. A spiral shape of micro-feature having a unique cross-section was employed on the tool shoulder and welding was performed at a tool travel speed of 1000 mm/min at two plunge depths (0.10 and 0.14 mm). The forces, temperature and material distribution ‘during welding’ and the surface finish, microstructure, microhardness and tensile property of the weld obtained ‘post welding’ were analyzed and compared with that of the welds obtained with featureless tool shoulder. It was found that low temperature welding with better surface finish and tensile property could be achieved with micro-featured tool shoulder at 0.14 mm plunge depth even at high tool travel speed of 1000 mm/min.

3-D Finite Element Simulation of Friction Stir Welding Process of Non Similar Aluminum-Copper Sheets

2011 ◽  
Vol 312-315 ◽  
pp. 953-958 ◽  
Author(s):  
A. Alimoradi ◽  
M. Loh-Mousavi ◽  
R. Salekrostam
Keyword(s):  
Finite Element ◽  
Friction Stir Welding ◽  
Heat Input ◽  
Three Dimensional ◽  
Welding Process ◽  
Process Conditions ◽  
Friction Stir ◽  
Two Parameters ◽  
Tool Pin ◽  
The Relationship

The Friction Stir Welding (FSW), a relatively new welding process, was developed in 1991 at the Welding Institute near Cambridge, England. There are two tool speeds to be considered in friction-stir welding; how fast the tool rotates and how quickly it traverses the interface. These two parameters have considerable importance and must be chosen with care to ensure a successful and efficient welding cycle. The relationship between the welding speeds and the heat input during welding is complex. In this paper the friction stir welding (FSW) process of stainless steel alloys has been modeled using a three dimensional finite element method. A coupled thermal viscoplastic model was used for the simulation. Tool speeds and temperature distribution are coupled and solved together using this method. The relationship between the welding speeds and the heat input during welding is obtained by numerical analysis, and the stress contour occurred by temperature field and tool force is surveyed. In addition, the effects of FSW process conditions on heating mainly near the tool pin are investigated in this paper.

scholarly journals Influence of Tool Geometry and Process Parameters on the Properties of Friction Stir Spot Welded Multiple (AA 5754 H111) Aluminium Sheets

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1157
Author(s):  
Danka Labus Zlatanovic ◽  
Sebastian Balos ◽  
Jean Pierre Bergmann ◽  
Stefan Rasche ◽  
Milan Pecanac ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Process Parameters ◽  
Spot Welding ◽  
Minimum Energy ◽  
Tool Geometry ◽  
Friction Stir ◽  
Minimum Energy Consumption ◽  
Punch Test ◽  
Wide Range ◽  
Lap Welding

Friction stir spot welding is an emerging spot-welding technology that offers opportunities for joining a wide range of materials with minimum energy consumption. To increase productivity, the present work addresses production challenges and aims to find solutions for the lap-welding of multiple ultrathin sheets with maximum productivity. Two convex tools with different edge radii were used to weld four ultrathin sheets of AA5754-H111 alloy each with 0.3 mm thickness. To understand the influence of tool geometries and process parameters, coefficient of friction (CoF), microstructure and mechanical properties obtained with the Vickers microhardness test and the small punch test were analysed. A scanning acoustic microscope was used to assess weld quality. It was found that the increase of tool radius from 15 to 22.5 mm reduced the dwell time by a factor of three. Samples welded with a specific tool were seen to have no delamination and improved mechanical properties due to longer stirring time. The rotational speed was found to be the most influential parameter in governing the weld shape, CoF, microstructure, microhardness and weld efficiency. Low rotational speeds caused a 14.4% and 12.8% improvement in joint efficiency compared to high rotational speeds for both tools used in this investigation.

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