Atomized powder, thermal spray coating, hearth roll, and method for producing hearth roll
An atomized powder has a heat-resistant alloy phase and a Cr 7 C 3 phase dispersed in the heat-resistant alloy phase, and contains 20 to 46% of Ni, 22 to 43% of Cr, 4 to 13% of Al, 0.1 to 1.0% of Y, and 0.3 to 4.2% of C on a mass basis, and a remainder thereof includes Co and unavoidable impurities.
1 . An atomized powder comprising a heat-resistant alloy phase and a Cr 7 C 3 phase dispersed in the heat-resistant alloy phase, wherein
the heat-resistant alloy phase is a Co-based alloy phase,
the atomized powder contains 20 to 46% of Ni, 22 to 43% of Cr, 4 to 13% of Al, 0.1 to 1.0% of Y, and 0.3 to 4.2% of C on a mass basis, and a remainder thereof includes Co and unavoidable impurities, and
a content of Cr 7 C 3 in the atomized powder is not less than 5 mass % and not greater than 20 mass %.
2 . The atomized powder according to claim 1 , wherein a part of the Cr 7 C 3 phase is a needle-like structure.
3 . The atomized powder according to claim 1 , wherein a proportion of the Cr 7 C 3 phase in a cross-sectional structure of a particle is not greater than 50 area %.
4 . A thermal spray coating formed using the atomized powder according to claim 1 .
5 . A hearth roll comprising a roll body and a thermal spray coating, the thermal spray coating being provided on a surface thereof, wherein
the thermal spray coating is the thermal spray coating according to claim 4 .
6 . A method for producing a hearth roll including a roll body and a thermal spray coating, the thermal spray coating being provided on a surface thereof, the method comprising:
forming a thermal spray coating on a surface of the roll body using the atomized powder according to claim 1 ; and
then hardening the thermal spray coating by heat-treating the thermal spray coating.
7 . The method for producing the hearth roll according to claim 6 , further comprising decreasing a hardness of the heat-treated thermal spray coating by melting and solidifying a surface of the heat-treated thermal spray coating by applying a laser beam to the thermal spray coating after heat-treating the thermal spray coating.