The use of nanotechnology to improve the bulk and surface properties of steel for structural applications - Nanotechnology in Eco-efficient Construction - page 92

Production
process

Microstructure of surface
layer

Novel properties or
phenomenon Reference Steel type Mechanism(s)

Ba et al.
(2011)

Gradient microstructure
with Lamellar-type
dislocation cells with
dense dislocation walls

Surface
nanocrystallization:
decomposing the
cementite granules

Dislocation activities

Kim et al.
(2009)

Low-carbon
steel
(0.15% C)

ECAP α − α ′ dual phase

microstructure with
ultrafi ne grains

Enhanced hardness and
strength but reduced
wear resistance

'Lack of strain
hardening due to
unstable and
non-equilibrium
(GBs) and the
cracking at the
interface of α − α ′

phases'

Huang et al.
(2011)

Low-carbon
steel
(

Quenching + Net-shape pearlite along

the GBs of

Enhanced strength,
stronger surface
passivation, and
reduced adhesive bond
shear strength, friction
coeffi cient and wear rate

Grain refi nement
induced by SPD tempering + α ( ∼ 500 nm)

≤ 0.2% C) ECAP

Verezub et
al. (2011)

Low-alloy
steel
(105WCr6)

In situ laser
melt
injection

20-30 vol% nano-sized
(Fe,W) 6 C particles and
∼

Enhanced microhardness
and wear resistance at
the 1 mm top layer

Strenghening by
nano- and
micro-precipitates + 56 vol% (W,Ti)C

microparticles in the
steel matrix

heat
treatment