kõrgel temperatuuril (üle 600 °C) metallurgilistele muutustele vastupidav heade tugevusomadustega roomekindel teras; tavaliselt ka kuumuspüsiv teras (vt kuumustugevus, kuumustugev sulam), a steel suitable for use at 600 oC or above retaining enough strength at elevated temperatures to be structurally useful and generally resist undergoing metallurgical changes weaken or embrittle the material (see: high-temperature strength, superalloy)