How does temperature affect steel strength?
A. For hot rolled structural steel the yield strength reduces as the temperature increases dropping to about 60% of its ambient temperature strength at around 400°C and approximately 10% at 800°C. However the stress at 2% strain (normally reached when a steel floor beam attains its permitted limit of deflection) initially increases with increasing temperature reaching a peak value at around 250°C. The reason for this can be explained using metallurgical theory and involves a combination of work hardening and dynamic strain ageing.
