Test pieces are used for establishing mechanical properties. When the test is done. Four values (a,b,c and d) are obtained.
The stress required to rupture in tension (pull) , expressed in Megapascals (MPa). Also called
Breaking Strength, Ultimate Strength and Ultimate Tensile Strength.
The stress at which a material exhibits a specified limiting set, commonly taken by the offset
method as 0.20 per cent of the specimen`s original length, expressed in Megapas-cals.
The amount of permanent stretch, after fracture in tension, expressed as a percentage of the specimen`s original length.
REDUCTION OF AREA
The difference between the original cross sectional area of a specimen and the least cross sectional area after rupture in tensile tests, expressed I percentage of the original cross-sectional area.
A measure of toughness. The force to fracture a notched specimen with a single blow. Expressed in Joules (J) or foot-pounds of the energy absorbed. Designated as "Charpy" or "Izod" Impact Strength, depending on the testing machine used.
An operation or combination of operations involving the heating and cooling of a metal to obtain certain desirable conditions or properties, and not for the sole purpose of me-chanical working.
The property which permits deformation under tension without rupture. Values of 'Elongation'
and 'Reduction of Area' are generally taken as a measure of Ductility.
Resistance to plastic deformation by indentation, penetration, scratchimg or bending. Expressed by means of 'Brinell', 'Rockwell', 'Scleroscope' or 'Vickers' Hardness numbers, depending upon the testing machine used and should be read in conjuction with specified mechanical required.
Heating and cooling to effect the release of stresses contained in material induced by heating, welding or machining.
Bringing about an intermediate condition in steel between being ductile and very hard, to provide a desired combination of hardness and ductility, to achieve prescribed mechanical properties.
This is the process carried out after material has been heated to the required tempera-ture. The material is then immersed in specific cooling agents to attain hardness which is dependent on the cooling speed which is possible for the hardening temperature con-cerned.
In applications where it is necessary for components to have great toughness but, at the same time must have a high resistance to wear, the required hardness can be achieved by case hardening the outer surface by means of one of the following methods:
- Flame Hardening
- Induction Hardening
The maximum section on which certain mechanical properties are guaranteed according to the British Standard Specification, BS 970 Pt of 1983.