LOW
THERMAL-EXPANSION,
SUPER ALLOY HRA929 FOR GAS TURBINES
Overview
Kovar alloys composed of
Fe-36Ni invar alloy and Fe-29Ni-17Co are known for their generally
low coefficients of thermal expansion. But, because they are not
particularly strong, these alloys are not suitable for parts that
are used in high-stress environments or exposed to high temperatures.
However, HRA929, which Hitachi Metals developed using alloy design
techniques, has not only a low coefficient of thermal expansion but
also [illegible] precipitation strength, enabling it to retain its
strength in temperatures of up to approximately 650°C. Furthermore,
this alloy displays superior structural stability and ductility.
Features
(1) Low coefficient of thermal expansion,
close to that of Kovar.
Figure 1: Average coefficient
of thermal expansion of various alloys
(2) Retains its strength at room and high temperatures at levels
close to Alloy 718, which is known for its strength at high temperatures.
Figure 2: Tensile strength of
various alloys
(3) High creep rupture strength does not show notched sensitivity.
Figure 3: Creep rupture properties
of various alloys
Compared with conventional [illegible] precipitation-strengthened,
low-expansion type Alloy903 and Alloy909, HRA929 has an even lower
coefficient of thermal expansion, and creep rupture notch sensitivity
and structural stability are improved.
Uses
Based on these benefits, HRA929 can
be combined with ceramics or glass and used in parts that need to
show high strength at room and high temperatures, and in gas turbine
equipment requiring tight clearance at high temperatures.
Inquiries
Specialty Steel Company
Tel.: +81-3-5765-4396 Inquiry Form
™
