Solid solution strengthening

Hardening (computing)

Yield (engineering)

Metallurgy

Materials science

Layer (electronics)

Ultimate tensile strength

Strain hardening exponent

Creep

Microstructure

Composite material

Chemistry

Tension (geology)

The Physics of Metals and Metallography

An analysis of mechanical properties has been performed for 12% Cr and 9% Cr steels by means of tension tests at 20 and 650°C and yield tests at 650°C and applied stresses of 200–100 MPa with a step of 20 MPa. The yield strength and ultimate tensile strength of the 12% Cr steel are, correspondingly, 614 and 710 MPa at 20°С and 365 and 390 MPa at 650°C. At both temperatures, the strength properties of the 12% Cr steel under tension are better than for the 9% Cr steel due to higher values of contributions from solid-solution hardening (+30 MPa) and substructural hardening (+23 MPa) to the room-temperature yield strength. The analysis of creep properties shows that the time to fracture at high stresses for the 12% Cr steel is much longer than for the 9% Cr steel due to a more prolonged transient creep stage and, at low applied stresses, there is almost no difference in the creep behavior of the 12% Cr and 9% Cr steels. The 1% creep limit estimated from the empirical dependence between the stress and the time required to attain the strain with a degree of 1% for the 12% Cr steel is 82 MPa, being comparable with the 1% creep limit of the 9% Cr steel.

Analysis of Mechanical Properties for the Heat Resistant Co-Modified 12 and 9% Cr Steels