Fusion Welding Process

Overview

Fusion welding processes- Fusion welding is a joining process that uses fusion of the base metal to make the weld. The three main type of the fusion welding are as follows:

1. Gas Welding :
Oxyacetylene welding (OAW)

2. Arc Welding :
Shielded metal arc welding (SMAW)
Gas-tungsten arc welding (GTAW)
Plasma arc welding (PAW)
Gas-metal arc welding (GMAW)
Flux-cored arc welding (FCAW)
Submerged arc welding (SAW)
Electroslag arc welding (ESW)

3. High-energy beam welding :
Electron beam welding (EBW)
Laser beam welding (LBW)

Since there is no arc involved in in the electroslag welding process, it is not exactly an arc welding process. For convenience of discussion, it is grouped with arc welding processes.

Electroslag strip Cladding

Fusion Welding

(REF.- Welding Metallurgy, Second Edition. Sindo Kou Copyright 􀂶 2003 John Wiley & Sons, Inc. ISBN: 0-471-43491-4)

Comments

Oxyacetylene Welding (OAW)

OXYACETYLENE WELDING The Process:- Gas welding is a welding process that melts and joins metals by heating them with a flame caused by the reaction between a fuel gas and oxygen. Oxyacetylene welding (OAW), shown in Figure is the most commonly used gas welding process because of its high flame temperature. A flux may be used to deoxidize and cleanse the weld metal. The flux melts, solidifies, and forms a slag skin on the resultant weld metal. Three different types of flames in oxyacetylene welding: neutral, reducing, and oxidizing , which are described next. Advantages and Disadvantages :- The main advantage of the oxyacetylene welding process is that the equipment is simple, portable, and inexpensive.Therefore, it is convenient for maintenance and repair applications. However, due to its limited power density, the welding speed is very low and the total heat input per unit length of the weld is rather high, resulting in large heat-affected zones and severe distortion.The...

Flux-Core Arc Welding (FCAW)

FLUX-CORE ARC WELDING (FCAW) The Process:- Flux-core arc welding (FCAW) is similar to GMAW , as shown in Figure a. However, as shown in Figure b, the wire electrode is flux cored rather than solid; that is, the electrode is a metal tube with flux wrapped inside. The functions of the flux are similar to those of the electrode covering in SMAW , including protecting the molten metal from air. The use of additional shielding gas is optional. Flux-Core Arc Welding (FCAW) (a) overall process (b) welding area enlarged Advantages of FCAW:- High deposition rates Deeper penetration than SMAW High quality welds Less pre-cleaning than GMAW Slag covering helps with out-of-position welds Self-shielded FCAW is draft tolerant Disadvantages of FCAW:- Slag must be removed Higher fume generation than GMAW and SAW Spatter Equipment is more expensive and complex than SMAW FCAW wire is more expensive Types of continuous wire electrodes:- Read ...

Shielded metal arc welding (SMAW)

SMAW The Process:- Shielded metal arc welding (SMAW) is a process that melts and joins metals by heating them with an arc established between a sticklike covered electrode and the metals, as shown in Figure below. It is often called stick welding . The electrode holder is connected through a welding cable to one terminal of the power source and the workpiece is connected through a second cable to the other terminal of the power source (Figure a). The core of the covered electrode, the core wire, conducts the electric current to the arc and provides filler metal for the joint. For electrical contact, the top 1.5 cm of the core wire is bare and held by the electrode holder. The electrode holder is essentially a metal clamp with an electrically insulated outside shell for the welder to hold safely. The heat of the arc causes both the core wire and the flux covering at the electrode tip to melt off as droplets (Figure b ). The molten metal collects in the weld pool and solidifies ...

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