Introduction

A welded joint is a permanent joint. Instead of casting or forging, welding is used to fabricate parts which are light, strong, and economical. The parts to be joined are heated, either by electric arc or gas, up to the fusion temperature of the material and then a filler material is used to fuse with the base parts. On cooling, a strong joint is formed. Welding is also used in repair work to join broken parts. It can also be used to reform a worn surface and then do machining.

Welded versus Riveted Joint

While deciding on the type of a joint, the following points are to be considered:

The advantages of welded joints over riveted joints are:

• • These are lighter than riveted joints, as no gusset plate or cover plates, etc., are used.

• • Manufacturing cost is less as there is no hole drilling or rivet head forming required.

• • Unlike riveted joints, there is no weakening of member due to the stress concentration caused due to a rivet hole and hence their efficiency may be 100 per cent.

• • These can be used at places where even a riveted joint is not possible, for example, joining a pipe.

• • Welding process is faster than riveting.

• • These joints are leak proof as compared to riveting.

• • Appearance is better than riveted joints due to absence of rivet heads.

In spite of all the advantages mentioned above, these joints do have some disadvantages also, as given below:

• • The joint can distort the members due to additional stresses that are developed due to heat; hence, stress relieving is done by heat treatment.