Basic welding principles
учебно-методический материал по английскому языку (11 класс)

Basic welding principles

Before reading: What materials can be joined by welding processes?

Study the following vocabulary.

1. Scan the text and name types of welding joints described in the text.
2. Read the text thoroughly (carefully) and complete the tasks after the text.

Fastening together the parts of work implement began when an individual attached a stick to a stone to make a spear or ax. However, it was a longtime before the ancients discovered a method for joining metals. As techniques were further developed, modern and advanced types of welding appeared.

Welding is an operation whereby two or more parts are united by meansof heat or pressure or both. It is usually used on metals and thermoplastics butcan also be used on wood.

           Welding is the least expensive process and widely used nowadays in fabrication commonly used across a range of industries including aerospace, automotive, energy, and construction amongst others.

            How welding works.

Joining Metals: The high heat causes a weld pool of molten materialwhich cools to form the join, which can be stronger than the parent metal.Pressure can also be used to produce a weld, either alongside the heat or byitself.

Joining Plastics: Plastics welding also uses heat to join the materials.Firstly, the surfaces are prepared before heat and pressure are applied and, finally, the materials are allowed to cool to create fusion.

Joining Wood: Wood welding uses heat generated from friction to join thematerials. The materials to be joined are subjected to a great deal of pressurebefore a linear friction movement creates heat to bond the workpieces together.

             More than 30 different types of welding exist, and they range from simpleoxyfuel to high-tech processes such as laser beam welding. However, onlysome welding types are used commonly, and they are Arc welding, Gas welding, Resistance welding, Newer welding, and Solid-State welding.

Factors affecting weldability: Thermal conductivity, Melting point, Thermal expansion, Surface condition, Change in the microstructure.

     There are basically five typesof welding joints: Butt, Corner,Lap, T(ee) and Edge joints.

        Butt Joint: The joint which isformed by placing the ends of two                                                       parts together is called a butt joint.

        Corner Joint. The joint formedby placing the corner of two partsat the right angle is called a cornerjoint. Two parts which are goingto be weld with a corner joint formthe shape of L.                            

T-Joint. The joint which is made by intersecting two parts at a right angle

(i.e at 90 degrees) and one part lies at the centre of the other. It is called a Tjoint, as the two parts welded look like English letter ‘T’.

Lap Joint. The lap joint is formed when the two parts are placed one overanother and then welded. It may be one-sided or double-sided. These typesof welding joints are mostly used to join two pieces with different thicknesses.

Edge Joint. The joint formed by welding the edges of two parts together iscalled an edge joint. This joint is used where the edges of two sheets are adjacent and are approximately parallel planes at the point of welding. In thisjoint the weld does not penetrate completely the thickness of joint, so it cannot be used in stress and pressure application.

             The Parent metal is metal to be joined or surfaced by welding, braze welding or brazing.

             The Filler metal (or consumable) is metal added during welding, braze welding, brazing or surfacing. Consumables are usually chosen to be similar in composition to the parent material, thus forming a homogenous weld, but there areoccasions, such as when welding brittle cast irons, when a filler with a very different composition and, therefore, properties is used. These welds are calledheterogeneous. The completed welded joint may be referred to as a weldment.

Ex.1. Find the translation of welding joints.

Ex.2. Identify the types of welding joints.

Ex.3. Find the translation.

Ex.3. Find the description of joints.