Sj. Kim et Cm. Wayman, STRENGTHENING BEHAVIOR AND EMBRITTLEMENT PHENOMENA IN FE-NI-MN-(TI) MARAGING ALLOYS, Materials science & engineering. A, Structural materials: properties, microstructure and processing, 207(1), 1996, pp. 22-29
The effects of manganese and titanium on the mechanical properties of
Fe-20Ni-(1.0-3.5)Mn-(0-1.0)Ti maraging steels were studied in order to
investigate the strengthening behaviour and embrittlement phenomena i
n Go-free Fe-Ni-Mn maraging steels. Marked changes in tensile properti
es occurred as a function of ageing time and temperature, and alloy co
mposition. As the amount of Mn and Ti increased, strength increased dr
astically but suffered from severe embrittlement. The strengthening be
haviour of aged specimens was explained by the well-known Orowan mecha
nism. There was no evidence of second phase precipitation and no segre
gation of Mn along grain boundaries, which have been suggested as the
proofs for the explanation of the embrittlement phenomena by many rese
archers. It is proposed that the combined amount of (Mn + Ti) should b
e controlled to below 3.5 wt.% in order to avoid severe embrittlement
in Fe-20Ni-Mn-Ti maraging alloys, where the amount of Ti is held to 1.
0 wt.%. The best combination of yield strength (1371 MPa) and elongati
on (18.8%) was obtained after ageing Fe-20.8Ni-2.13Mn-0.8 Ti alloy for
1 h at 450 degrees C.