Steel piston

a steel piston and crown technology, applied in the field of steel pistons, can solve the problems of cracking in the crown of the piston of the steel piston, and achieve the effects of excellent machinability, toughness, and excellent high temperature fatigue strength

Active Publication Date: 2021-08-26
NIPPON STEEL CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present patent describes a steel piston that can withstand high temperatures, during production and use. The steel piston is easy to produce and has excellent fatigue strength and toughness. Additionally, it has the ability to withstand fatigue at weld heat-affected zones, which can be a potential weak point in the piston.

Problems solved by technology

As a result of the scale notch (region from which the oxide scale peeled off) widening, a crack occurs in the piston crown of the steel piston.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0267]Molten steels having the chemical compositions shown in Table I were produced.

TABLE 1TestChemical Composition (unit is mass %; balance is Fe and impurities)NumberCSiMnPSCrMoVAlNOCuNiNbCaF1F210.190.610.630.0080.0181.180.240.310.0330.00520.0013———0.00021.171.2920.220.320.710.0110.0081.200.280.270.0380.00640.0012———0.00011.090.9630.170.760.320.0090.0121.420.220.340.0290.00810.0018———0.00021.241.5540.210.280.650.0080.0021.220.160.120.0320.00510.0011———0.00040.520.7550.190.460.720.0090.0221.480.330.380.0180.00760.0021———0.00011.471.1560.160.940.780.0140.0261.390.280.150.0450.01470.00280.12——0.00020.730.5470.290.080.230.0090.0030.920.180.110.0120.01220.0009—0.16—0.00020.510.6180.220.290.750.0110.0161.220.240.320.0070.00460.0011——0.0270.00041.201.3390.240.340.770.0120.0141.320.270.220.0230.00780.00090.150.21—0.00030.930.81100.110.420.780.0060.0221.230.210.260.0420.00810.0009———0.00020.991.24110.390.080.640.0090.0031.190.240.310.0320.00410.0011———0.00031.171.29120.180.450.720.0120.021...

example 2

[0325]Whether or not it was possible to join different steel materials together was investigated assuming Test Number 2 in Table 1 as the upper member of the steel piston, and Test Number 24, and Test Numbers 26 and 27 having the chemical compositions shown in Table 3 as the lower member of the steel piston.

TABLE 3TestChemical Composition (unit is mass %; balance is Fe and impurities)NumberCSiMnPSCrMoVAlNOCuNiNbCaF1F2260.360.200.780.0080.0181.160.16—0.0280.00500.0017————0.160.00270.380.721.360.0110.0250.130.030.120.0190.01400.0018————0.394.00

[0326]The chemical composition of the steel material of Test Number 26 was a chemical composition equivalent to SCM435 in the JIS Standard. The chemical composition of Test Number 27 was a chemical composition of a well-known non-heat treated steel containing V.

[0327]The steel materials of Test Numbers 26 and 27 were produced by the following method. The molten steels having the chemical compositions shown in Table 3 were subjected to primary re...

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Abstract

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 mm2 or 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 mm2, and the number of oxides is 15.0 per mm2 or less.0.42≤Mo+3V≤1.50  (1)V / Mo≥0.50  (2)

Description

TECHNICAL FIELD[0001]The present disclosure relates to a piston, and more particularly relates to a steel piston that is utilized in an engine or the like.BACKGROUND ART[0002]An engine as typified by a diesel engine or the like includes a piston. The piston is housed inside a cylinder of the engine, and performs a reciprocating motion inside the cylinder. The piston is exposed to heat of a high temperature in a combustion process during operation of the engine.[0003]Most conventional pistons are produced by casting aluminum. However, in recent years there is a demand to further improve the combustion efficiency of engines. In the case of a piston, which is an aluminum casting product, the surface temperature during use is within the range of around 240 to 330° C.[0004]Recently, the use of pistons in even higher combustion temperatures ranges to increase the combustion efficiency is being studied. Therefore, there is a need for a piston that can endure a situation in which the surfac...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): F02F3/00F16J1/01
CPCF02F3/0084F02F2003/0007F16J1/01F02F3/00C22C38/22C22C38/24C22C38/26C22C38/001C22C38/002C22C38/06C22C38/04C22C38/02C21D2211/004C21D9/0068C21D1/25C21D1/18C21D1/20C21D2211/002C21D2211/009C21D2211/005C22C38/20C22C38/44C22C38/46B21K1/18B21J1/06
Inventor NEISHI, YUTAKATSUBOTA, YORIMASAOOSATO, KOUJIETO, HIROHITONAGAI, WATARUYAMADA, YOSHITOMI
Owner NIPPON STEEL CORP
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