P91 Alloy Steel (UNS K91560) – Composition, Properties and Uses
P91 Alloy Steel Mechanical Properties. Alloy steel grade P91 has excellent mechanical properties due to its composition. It has a yield strength of 85 ksi (586 MPa), while its tensile strength ranges from 95-110 ksi (655-758 MPa). It also has an elongation rate between 15-20%. The hardness rating is generally between 280-320 HBW.