In
recent yea
rs, the
re has been significant inte
rest in the development of high silicon
bainitic steels. This has been due to thei
r excellent mechanical p
rope
rties, including ve
ry high st
rength, good ductility, high f
ractu
re toughness, and high wea
r resistance. Recently, a high-st
rength, high-toughness
bainitic steel with a high silicon content has been developed by two of the autho
rs. In this pape
r, the mechanical p
rope
rties as a function of austempe
ring a
re p
resented. A low-ca
rbon, low-alloy (LCLA)
bainitic steel with a high (2%) silicon content was quenched and isothe
rmally austempe
red at tempe
ratu
res f
rom 260 掳C to 343 掳C fo
r 2 h. The heat t
reatment p
roduced a mic
rost
ructu
re consisting of tempe
red ma
rtensite with austenite located between the ma
rtensite laths. The mechanical p
rope
rties of these austempe
red samples, including plane-st
rain f
ractu
re toughness, we
re cha
racte
rized and compa
red with as-cast samples. All of the austempe
ring t
reatments p
roduced high st
rength (>1500 MPa UTS) and high f
ractu
re toughness (>105 MPa) with
reasonable ductility (>4%).
A promising potential application of this steel is a military vehicle armor plate; therefore, a small number of impact tests were performed to qualitatively assess the improvement in resistance. Impact testing was performed using projectiles propelled by a light gas gun; targets of mild steel and LCLA austempered at 316 掳C were evaluated. Qualitative results reveal that, in comparison to the mild steel sample, the austempered LCLA samples suffered reduced damage and no penetration.