The use of nanotechnology to improve the bulk and surface properties of steel for structural applications - Nanotechnology in Eco-efficient Construction - page 83

Table 5.1 Continued

Production
process

Microstructure of bulk
material

Novel properties or
phenomenon Reference Steel type Mechanism(s)

Taneike et al.
(2003)

ODS -steel

(0.002C-9Cr-
3W-3Co-0.2V-
0.06Nb-0.05N)

α ′ Conventional

processing
techniques
(including heat
treatment)

High density of
nano-precipitates
(5-10 nm) 'along
prior (

Outstanding high-
temperature creep
resistance (at 923K,
time-to-rupture two
orders of magnitude
higher than
conventional creep-
resistant steels);
suffi cient fracture
toughness (100-150 J
at room temperature)

Carbonitride
nano-precipitates
pin the GBs

GBs) as
well as along lath,
block, and packet
boundaries'

γ

Kim et al. (2003) ODS 12YWT

α

MA Uniform distribution

of Ti and W;
dispersion of
nano-sized complex
Ti-Y-O oxides

Outstanding high-
temperature TS and
creep rupture strength

Solid solution
hardening by W;
dispersion
strengthening by
nanoparticles

-steel

Klueh et al.
(2005)

ODS 9Cr-1Mo
α ′

TMT:
austenitizing

MX precipitates
(30 nm) at 7-8

Outstanding high-
temperature tensile
and creep strength
(600-750°C or higher)

Strengthening effect
of nano-scale MX
precipitates (VN,
NbC, or NbNC)

-steels +

10 18 m -3 and M 23 C 6
(130-150 nm) at 3-6
×

×

cooling + hot

rolling

annealing

+

+ 10 19 m -3

normalizing +

tempering

Ohtsuka et al.
(2007)

ODS 9Cr
α ′

MA + annealing Hard grains

(residual-

Increasing [Ti] to 0.30-
0.35% greatly improves
creep strength

Ti increases
residual- -steels ) and

soft grains
(tempered

α grains

that suppress the
GB sliding

α

α ′ )