Fe-Ni-Al, Fe-Ni-TiおよびFe-Ni-Co-Mo 系マルエージ鋼の析出硬化および磁性*
1974 年 60 巻 9 号 p. 1363-1372
詳細
1974 年 60 巻 9 号 p. 1363-1372
Precipitation hardening, tensile properties, and D. C. magnetic properties of Fe-(5-20)% 1.57)%Al, Fe-(5-20)% Ni-(0.5-4.8)%Ti, and Fe-(8-18)% Ni-10% Co-5% Mo maraging steels were investigated.
Maximum hardness produced by aging at 475 C were measured as a function of additional amount of aluminium or titanium. In the nickel range from 10 to 20%, titanium addition is more effective in hardening than aluminium addition is. However, in 5% nickel level, aluminium addition is more helpful in age-hardening.
It is considered that a meta-stable phase is formed in aging the Fe-18% Ni-l0% Co-5% Mo and Fe-14% Ni-10% Co-5% Mo maraging steels at 425°C Precipitation hardening produced by aging the Fe-10% Ni-10% Co-5% Mo and Fe-8% Ni-10% Co-5% Mo maraging steels at 425°Cis markedly decreased. Accordingly, it is implied that either meta-stable phase is not formed or is slightly formed in aging at 425°C
Small amounts of pearlite structure formed by the cellular precipitation reaction are found in the Fe-5% Ni-1.57% Al maraging steel aged at 475°Cfor 50 hr and 100 hr. Except the Fe-5% Ni-1.57% Al maraging steel, the pearlite cellular structure is not found in the Fe-Ni-Al maraging steels, aged at 475°C nearly to their maximum hardness.
Considerable drop in toughness is often observed in the Fe-Ni-Ti maraging steelsage-hardened at 475°C to hardness over about Hv; 450. Molybednum addition is effective in suppressing the drop in toughness. The upper limit of the tensile strength of the Fe-Ni-Al maraging steels aged at 475°Cis about 140 Kg/mm2. Regarding the Fe-Ni-Al, and Fe-Ni-Ti maraging steels having tensile strength less than about 140 kg/mm2, no difference in elongation is found in tensile test.
Magnetic properties of the maraging steels depend mainly on their chemical compositions. On comparing coercive force and magnetic induction at the same hardness level, the magnetic properties of the Fe-Ni-Al maraging steels are softest and those of the nickel maraging steels containing cobalt and molybdenum are hardest.
