# US 2019/0376479 A1 · Method for manufacturing fuel injection component

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- Number: US 2019/0376479 A1
- Document ID: US20190376479A1
- Status: Published application
- Kind: A1
- Application number: 16/431,871
- Filed: 2019-06-05
- Published: 2019-12-12
- Earliest claimed: 2018-06-07
- Assignees: Denso Corporation
- Applicants: Denso Corporation
- Inventors: Makoto HARITANI; Yuuki TANAKA; Tomohiro ANDOH; Kazuyoshi KIMURA; Takahiro MIYAZAKI; Keisuke INOUE; Toshimasa ITO; Koji MORITA; Tomomitsu FUKUOKA; Tadashi NISHIWAKI
- Web page: https://patentgrep.com/patent/US20190376479A1

## CPC

- F02M 61/168: {Assembling; Disassembling; Manufacturing; Adjusting}
- C21D 6/004: {containing Cr and Ni}
- C21D 6/005: {containing Mn}
- C21D 6/008: {containing Si}
- C21D 9/0068: {for particular articles not mentioned below}
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C 38/105: {containing Co and Ni}
- C22C 38/16: containing copper
- F02M 55/025: {Common rails}
- F02M 2200/80: Fuel injection apparatus manufacture, repair or assembly
- F02M 2200/8069: involving removal of material from the fuel apparatus, e.g. by punching, hydro-erosion or mechanical operation
- F02M 2200/9061: Special treatments for modifying the properties of metals used for fuel injection apparatus, e.g. modifying mechanical or electromagnetic properties
- F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

A workpiece for a fuel injection component is made of a steel having compositions, by mass %, of C: 0.08 to 0.16%, Si: 0.10 to 0.30%, Mn: 1.00 to 2.00%, S: 0.005 to 0.030%, Cu: 0.01 to 0.30%, Ni: 0.40 to 1.50%, Cr: 0.50 to 1.50%, Mo: 0.30 to 0.70%, V: 0.10 to 0.40%, s-Al: 0.001 to 0.100%, and Fe and unavoidable impurities as remaining components. After heating the workpiece to a temperature of 950° C. or more and 1350° C. or less, the workpiece is subjected to a hot forging, and thereafter cooled at an average cooling rate of 0.1° C./sec. or more in a temperature range from 800° C. to 500° C., and at the average cooling rate of 0.02° C./sec. or more and 10° C./sec. or less in the subsequent temperature range from 500° C. to 300° C. to set an area ratio of a bainite structure after hot forging to 85% or more.

## Claims

### Claim 1

A method for manufacturing a fuel injection component by processing a workpiece into a predetermined shape, wherein the workpiece is made of a steel having compositions, by mass %, of
C: 0.08 to 0.16%,
Si: 0.10 to 0.30%,
Mn: 1.00 to 2.00%,
S: 0.005 to 0.030%,
Cu: 0.01 to 0.30%,
Ni: 0.40 to 1.50%,
Cr: 0.50 to 1.50%,
Mo: 0.30 to 0.70%,
V: 0.10 to 0.40%,
s-Al: 0.001 to 0.100%, and
Fe and unavoidable impurities as remaining components,
the method comprising:
subjecting the workpiece to hot forging after heating the workpiece to a temperature of 950° C. or more and 1350° C. or less;
first cooling the workpiece, after the hot forging, at an average cooling rate of 0.1° C./sec. or more in a temperature range from 800° C. to 500° C.; and
second cooling the workpiece, after the first cooling, at an average cooling rate of 0.02° C./sec. or more and 10° C./sec. or less in a subsequent temperature range from 500° C. to 300° C. to set an area ratio of a bainite structure after hot forging to 85% or more.

### Claim 2 (depends on 1)

The method according to claim 1, wherein
the steel further contains one or two of Ti: ≤0.100% and Nb: ≤0.100% by mass %.

### Claim 3 (depends on 1)

The method according to claim 1, wherein
a maximum diameter √areamax of non-metallic inclusions estimated by an extreme value statistical method in the workpiece after the hot forging is 300 μm or less.

### Claim 4 (depends on 1)

The method according to claim 1, further comprising:
performing, after the hot forging, an aging treatment in a temperature range of 550° C. to 700° C.

### Claim 5 (depends on 1)

The method according to claim 1, further comprising:
performing an autofrettaging process on the workpiece in which a fuel flow channel is formed.

### Claim 6 (depends on 1)

The method according to claim 1, further comprising:
performing machining on the workpiece.

### Claim 7 (depends on 1)

The method according to claim 1, further comprising:
performing machining on the workpiece to from a fuel flow channel in the workpiece; and
performing an autofrettaging process on fuel flow channel of the workpiece.