Glossary - T
A joint formed when one plate is joined to another at right angles to form a 'T'. This type of joint is most widely used in arc welding. A term which generally describes the mechanical properties of an alloy. Many steels may be hardened by quenching from high temperature and then softened by re-heating at a lower temperature to give the required properties, or 'temper'. Other alloy systems, like aluminium and copper, for example, start in the soft or annealed condition. With cold work, the strength of the alloy may be increased, accompanied by a reduction in ductility. Different degrees of cold work produce different properties, or 'tempers', e.g. annealed (soft), half-hard, fully hardened. The tensile strength of a material is the value obtained by dividing the breaking load by the cross-sectional area. Thermal Expansion, coefficient of When heated, most metals and alloys expand. The coefficient of thermal expansion is a second-order tensor, which describes the degree to which a particular metal or alloy expands when it is subjected to a uniform incremental temperature rise. A tungsten electrode normally used for TIG welding containing a small percentage of thorium to assist arc initiation. TIG stands for Tungsten Inert Gas welding, also known in the US as GTAW. TIG is an electric arc welding process which uses heat generated by an arc struck between a non-consumable tungsten electrode and the work piece. A term used to describe the defect on the top edge of the cut. It is usually caused by using too intense a pre-heat flame. The item of equipment in which the oxygen and the fuel gas are mixed and delivered to the nozzle. A term denoting a condition intermediate between brittleness and softness. It is indicated in tensile tests by measurement of the ultimate tensile stress and elongation. Gas which is injurious to health. A steel filler metal which has additions of three elements, aluminium, zirconium and titanium, in addition to manganese and silicon, to effect deoxidation of the weld pool. May also be described as 'multiple deoxidised'. The temperature and pressure at which the solid, liquid and gas phases of a substance co-exist.
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