A change in temperature can cause a change in the dimensions and mechanical properties of a steel wire. When a steel wire is heated, it expands due to thermal expansion, and when it is cooled, it contracts.
The amount of expansion or contraction of the wire depends on the coefficient of thermal expansion of the steel, which is a material property that describes how much the material expands or contracts per unit temperature change. For steel, the coefficient of thermal expansion is typically around 12 x 10^-6 / °C.
If a steel wire is subjected to a temperature change, its length and diameter may change, which in turn affects its mechanical properties such as its strength, stiffness, and ductility. For example, if a steel wire is heated and expands, its cross-sectional area will increase, which will decrease its stress and increase its strain for a given applied load. On the other hand, if a steel wire is cooled and contracts, its cross-sectional area will decrease, which will increase its stress and decrease its strain for a given applied load.
Therefore, it is important to take into account the effects of temperature when designing and analyzing steel structures and components, and to consider the coefficient of thermal expansion and the resulting changes in dimensions and mechanical properties that may occur due to temperature changes.