Hot modulus of rupture: the stress at which a refractory bar breaks in three-point bending while held at a test temperature, such as 1260, 1370 or 1480 C, under methods such as ASTM C583. It shows how strong the material is at service temperature and drops sharply with impurities that form glassy phases, such as lime, alkalis and iron. Two products with the same cold strength can differ several-fold in HMOR.
Cold strength looks great but HMOR at 1480 is under 2 MPa, that castable will slump at temperature.
Also heard as
- hot MOR
- hot modulus of rupture
- hot bend strength
Related terms
CCS
Cold crushing strength: the room-temperature compressive strength of a refractory, in MPa or psi.
RUL
Refractoriness under load: the temperature at which a refractory starts to deform under a small steady load.
Creep
Slow, permanent deformation of a refractory under steady load at high temperature over hours to years.
Refractoriness
Ability of a material to withstand high temperature without softening or melting.