26-08-2021 дата публикации
Номер: US20210262412A1
Принадлежит:
An upper member of a steel piston has a chemical composition which consists of, in mass %, C: 0.15 to 0.30%, Si: 0.02 to 1.00%, Mn: 0.20 to 0.80%, P: 0.020% or less, S: 0.028% or less, Cr: 0.80 to 1.50%, Mo: 0.08 to 0.40%, V: 0.10 to 0.40%, Al: 0.005 to 0.060%, N: 0.0150% or less, O: 0.0030% or less, and the balance: Fe and impurities, and satisfies Formula (1) and Formula (2), in which, at a cross section parallel to the axial direction of the upper member, the number of Mn sulfides is 100.0 per mmor less, the number of coarse Mn sulfides having an equivalent circular diameter of 3.0 μm or more is within a range of 1.0 to 10.0 per mm, and the number of oxides is 15.0 per mmor less. 1. A steel piston , comprising:an upper member including at least a top land of a crown portion, anda lower member arranged below the upper member and fixed to the upper member, the lower member including a skirt portion and a piston pin hole into which a piston pin is to be inserted;the upper member having a chemical composition which consists of, in mass %,C: 0.15 to 0.30%,Si: 0.02 to 1.00%,Mn: 0.20 to 0.80%,P: 0.020% or less,S: 0.028% or less,Cr: 0.80 to 1.50%,Mo: 0.08 to 0.40%,V: 0.10 to 0.40%,Al: 0.005 to 0.060%,N: 0.0150% or less,O: 0.0030% or less,Cu: 0 to 0.50%,Ni: 0 to 1.00%,Nb: 0 to 0.100%, andthe balance: Fe and impurities,and satisfies Formula (1) and Formula (2),wherein:at a cross section parallel to an axial direction of the steel piston in the upper member,{'sup': '2', 'a number of Mn sulfides containing 10.0 mass % or more of Mn and containing 10.0 mass % or more of S is 100.0 per mmor less,'}{'sup': '2', 'among the Mn sulfides, a number of coarse Mn sulfides having an equivalent circular diameter of 3.0 μm or more is within a range of 1.0 to 10.0 per mm, and'}{'sup': '2', 'claim-text': [{'br': None, '0.42≤Mo+3V≤1.50\u2003\u2003(1)'}, {'br': None, 'V/Mo≥0.50\u2003\u2003(2)'}], 'a number of oxides containing 10.0 mass % or more of oxygen is 15.0 per mmor less,'}where, a ...
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