Science:
Steel is the workhorse of our infrastructure. Stronger, tougher
steels are always needed to reduce weight and improve safety in
transportation, enhance architectural flexibility in
construction, and improve performance in heavy machinery. For
structural steels to be both strong and tough (resistant to
fracture), they must not be used at temperatures below the
ductile-brittle transition temperature, T
B, at which the steel loses its toughness and
fractures in a brittle mode. This transition results from a
competition between plastic deformation and brittle fracture at
the tips of cracks or flaws in the steel. It can be controlled
by techniques such as grain refinement that inhibit brittle
fracture, or by techniques such as controlled delamination that
facilitate plastic deformation. In last week's Science
magazine, Yuuji Kimura, Tadanobu Inoue, Fuxing Yin, and Kaneaki
Tsuzaki show how these approaches can be combined to achieve
low T
B and high toughness in an ultrahigh-strength
low-alloy steel.
Related Links
Inverse
Temperature Dependence of Toughness in an Ultrafine
Grain-Structure Steel
Science
320 1057 - 1060
