Iron-based sintered alloy for sliding member and production method therefor
An iron-based sintered alloy for sliding member, in which seizure resistance is improved, and a production method therefor, are provided. The iron-based sintered alloy for sliding member consists of, by mass %, 10 to 30% of Cu, 0.2 to 2.0 % of C, 0.03 to 0.9 % of Mn, 0.36 to 3.65% of S, and the balance of Fe and inevitable impurities in the overall composition. The iron-based sintered alloy for sliding member exhibits a metallic structure in which copper phases and pores are dispersed in the matrix that includes mainly a martensite structure and sulfide particles are dispersed in the matrix and the copper phases. The sulfide particles are dispersed at 1 to 30 vol. % with respect to the matrix.
1. An iron-based sintered alloy for a sliding member, the iron-based sintered alloy consisting of, by mass %:
more than 15% and 30% or less of Cu,
0.2 to 2.0% of C,
0.03 to 0.9% of Mn,
0.36 to 3.65% of S,
not more than 10 mass % of Ni,
not more than 10 mass % of Mo,
and the balance of Fe and inevitable impurities in the overall composition, wherein the iron-based sintered alloy exhibits a metallic structure in which:
copper phases and pores are dispersed in a matrix that contains mainly a martensite structure,
sulfide particles mainly containing iron sulfide are precipitated and dispersed in grain boundaries, the pores, the matrix, and the copper phases, and
the sulfide particles are dispersed at 1 to 30 vol. % with respect to the matrix.
2. The iron-based sintered alloy for sliding member according to claim 1 , wherein the copper phases are dispersed at 2 to 25 vol. % with respect to the matrix.
3. The iron-based sintered alloy according to claim 1 , wherein the sulfide particles include copper sulfides and/or complex sulfides of iron and copper.
4. The iron-based sintered alloy according to claim 1 , wherein the copper phases are dispersed at more than 5 vol. % and 25 vol. % or less with respect to the matrix.
5. A production method for the iron-based sintered alloy for a sliding member according to claim 1 , the method comprising: preparing an iron powder, a copper powder, a graphite powder, and at least one sulfide powder of an iron sulfide powder and a copper sulfide powder, the iron powder consisting of 0.03 to 1.0 mass % of Mn and the balance of Fe and inevitable impurities; forming a raw powder by mixing the copper powder, the graphite powder, and the sulfide powder with the iron powder so as to consist of, by mass %, more than 15% and 30% or less of Cu, 0.2 to 2.0% of C, 0.03 to 0.9% of Mn, 0.36 to 3.65% of S, and the balance of Fe and inevitable impurities; compacting the raw powder into a green compact with a predetermined shape; sintering the green compact at a temperature of 1000 to 1200° C.; and quench hardening and tempering the sintered compact.
6. The production method for the iron-based sintered alloy for sliding member according to claim 5 , wherein Ni or Mo is added in the form of an iron alloy powder by adding Ni or Mo to the iron powder, or Mo is added to the raw powder in the form of a nickel powder and a molybdenum powder in addition to or instead of the iron alloy powder, so that the raw powder further includes not more than 10 mass % of Ni or Mo.