Alloy material and method for producing same

An alloy material having a chemical composition consisting of, in mass %,

• C:
• 0.010 to 0.10%,
• Si:
• more than 0.10% to 0.50% or less,
• Mn:
• 0.05 to 0.50%,
• P:
• 0.015% or less,
• S:
• 0.0015% or less,
• Cr:
• 0.005 to 0.50%,
• Ni:
• 34.5 to 37.0%,
• Cu:
• 0.005 to 1.0%,
• Co:
• 0.005 to 0.50%,
• Mo:
• 0.001 to 0.50%,
• Al:
• 0.0001 to 0.050%,
• Nb:
• 0.001 to 1.0%,
• N:
• 0.010% or less,
• O:
• 0.0060% or less,
• Ti:
• 0.0200% or less,
• Zr:
• 0.0200% or less,
• Hf:
• 0.0200% or less,
• V:
• 0.500% or less,
• W:
• 1.000% or less,
• Sn:
• 0.050% or less,
• Zn:
• 0.0020% or less,
• Pb:
• 0.0010% or less,
• Ta:
• 0 to 1.0%,
• B:
• 0 to 0.010%,
• Ca:
• 0 to 0.0050%,
• Mg:
• 0 to 0.0030%,
• REM:
• 0 to 0.050%, and
• the balance:
• Fe and unavoidable impurities,
• and satisfying Formula (1), Formula (2), Formula (3) and Formula (4) below,
• wherein:
• a yield stress is 240 MPa or more, and
• a plate thickness is 3.0 mm or more;
• T0≤T1−2 (1)
• C—Nb/7.7−Ta/15≤0.045 (2)
• Nb—7.7C≤0.30 (3)
• Ta−15C≤0.30 (4)
• where, each symbol of an element in the above formulas represents a content (mass %) of a corresponding element, T0 represents a Curie temperature (° C.) of the alloy material, and T1 represents a Curie temperature (° C.) of the alloy material after the alloy material is held at 900° C. for one minute and thereafter is cooled under conditions such that an average cooling rate in a temperature range from 600 to 300° C. is 0.2° C./s.