Edge preparation and joint design
There are few more important decisions that affect the success of welding than that of correct joint design. Problems with weld quality or performance can often be attributed to the …
Welding position
Welding in the flat or downhand position is preferred for all arc welding activities. It is easier for the welder to deposit high-quality weld metal at high deposition rates in …
Welding speed
Aluminium is normally welded at higher travel speeds than when welding steels, particularly when using the MIG process. The implication of this is that abrupt changes of direction are to …
Access for welding
The two most common design faults are failing to recognise that full vision of the weld pool is essential for manual welding and that the weld must be at a …
Welding design
5.1 Introduction In all constructional applications where welded connections are used either a stress analysis is carried out or ample experience of acceptable performance exists for the specific joint design. …
Cleaning and degreasing
Components for welding may be flat, preformed, sheared, sawn or milled to give the desired shape or to provide the weld preparation. Lubricants used during these processes must be removed …
Mechanical cutting
Although the methods mentioned above can be applied to many fabricating activities, mechanical cutting techniques are used by most welding workshops as being the most cost-effective and versatile method. Cutting …
Water jet cutting
Water jet cutting uses an abrasive powder introduced into a very high - pressure and velocity water jet and is capable of cutting both metallic and non-metallic materials essentially by …
Laser beam cutting
A laser (light amplification by the stimulated emission of radiation) generates a coherent beam of light at an essentially constant wavelength. When this beam is focused on a surface there …
Plasma-arc cutting
Plasma-arc may be used for either cutting or welding and is the most widely used thermal process for cutting of aluminium alloys in manual, mechanised or fully automated modes (Fig. …
Storage and handling
Good handling practices are required if aluminium components are to be supplied to the customer in an unmarked condition. Aluminium is a relatively soft material and is easily scored or …
Preparation for welding
4.1 Introduction The need for degreasing and oxide removal has been covered in Chapter 2. This chapter will review both the handling and storage of aluminium and the options available …
Filler metal selection
Filler metal specifications are to be found in BS 2019 Part 4, although this will be replaced in the near future by a CEN specification. The BS specification lists 11 …
Specific alloy metallurgy
3.4.1 Non-heat treatable alloys 3.4.1.1 Pure aluminium (1XXX series) The principal impurities in ‘pure’ aluminium are silicon and iron, residual elements remaining from the smelting process. Copper, manganese and zinc …
CEN designation system
3.3.1 Alloy composition identification A full listing of all of the British and European specifications dealing with any aspect of aluminium alloys, product forms, supply conditions and welding is given …
Alloying elements
The principal alloying elements are copper, silicon, manganese, magnesium, lithium and zinc. Elements such as nickel, chromium, titanium, zirconium and scandium may be added in small amounts to achieve specific …
Designation criteria
Aluminium alloys may be divided into two broad classes, cast and wrought products. These two classes can be further subdivided into families of alloys based on chemical composition and finally …
Strength loss due to welding
In order to effect a weld the components to be joined are heated to a high temperature, in the case of fusion welding above the melting point of the parent …
Hot cracking
Hot cracking is a welding problem that does not occur in pure metals but may be found in certain alloy systems. It is not confined to the aluminium alloys but …
Oxide film removal during welding
The need to remove the oxide film prior to welding to reduce the risk of porosity has been covered above. It is also necessary to disperse this film 2.9 Oxide …
Aluminium weldability problems
2.3.1 Porosity in aluminium and its alloys Porosity is a problem confined to the weld metal. It arises from gas dissolved in the molten weld metal becoming trapped as it …
Precipitation (age) hardening
Microstructures with two or more phases present possess a number of ways in which the phases can form. The geometry of the phases depends on their relative amounts, whether the …
Cold working or strain hardening
Cold work, work hardening or strain hardening is an important process used to increase the strength and/or hardness of metals and alloys that cannot be strengthened by heat treatment. It …
Solid solution strengthening
Very few metals are used in the pure state, as generally the strength is insufficient for engineering purposes. To increase strength the metal is alloyed, that is mixed with other …
Structure of metals
Before discussing the principles by which metals achieve their mechanical strength it is necessary to have an appreciation of their structure and how these structures can be manipulated to our …
Strengthening mechanisms
There are five separate strengthening mechanisms that can be applied to the aluminium alloys. These are grain size control, solid solution alloying, second phase formation, strain hardening (cold work) and …
Welding metallurgy
Introduction Ideally a weldment - by this is meant the complete joint comprising the weld metal, heat affected zones (HAZ) and the adjacent parent metal - should have the same …
Welding: a few definitions
Before dealing with the problems of welding aluminium alloys there are a few definitions required, not least of which is welding itself. Welding can be described as the joining of …
Product forms
Aluminium is available in both wrought and cast forms. The wrought forms comprise hot and cold rolled sheet, plate, rod, wire and foil. The ductility and workability of aluminium mean …
Characteristics of aluminium
Listed below are the main physical and chemical characteristics of aluminium, contrasted with those of steel, the metal with which the bulk of engineers are more familiar. As can be …
Introduction
The existence of aluminium (Al) was postulated by Sir Humphrey Davy in the first decade of the nineteenth century and the metal was isolated in 1825 by Hans Christian Oersted. …
The welding of aluminium and its alloys
Gene Mathers Engineering is not an exact science and, of the many disciplines within engineering, welding is probably one of the most inexact - rather more of an art than …
