Automobile part and method for manufacturing automobile part

Patent metadata

Field	Value
Publication number	US-2016318093-A1
Application number	US-201415106136-A
Country	US
Kind code	A1
Filing date	Dec 17, 2014
Priority date	Dec 25, 2013
Publication date	Nov 3, 2016
Grant date	—

Abstract

[Object] There are provided automobile parts and a method for manufacturing the automobile parts. The automobile parts have an excellent corrosion resistance after coated with a electrodeposition paint with smaller thickness, improve formability and productivity in hot pressing, and also improve chemical conversion treatability after hot press-forming.
[Solution] An automobile part according to the present invention includes: a formed steel sheet having an intermetallic compound layer formed on a surface of the steel sheet, the intermetallic compound layer being formed of Al—Fe intermetallic compound having a thickness of 10 μm or more and 50 μm or less, the intermetallic compound layer including a diffusion layer positioned in closest proximity to the steel sheet, the diffusion layer having a thickness of 10 μm or less; a surface coating layer provided on a surface of the intermetallic compound layer, the surface coating layer including a coating containing ZnO and a zinc phosphate coating and having a surface roughness of 3 μm or more and 20 μm or less as a maximum profile height Rt in accordance with JIS B0601 (2001); and an electrodeposition paint film provided on a surface of the surface coating layer and having a thickness of 6 μm or more and less than 15 μm.

First claim

1 - 20 . (canceled)

21 . An automobile part, comprising:
a formed steel sheet having an intermetallic compound layer formed on a surface of the steel sheet, the intermetallic compound layer being formed of Al—Fe intermetallic compound having a thickness of 10 μm or more and 50 μm or less, the intermetallic compound layer including a diffusion layer positioned in closest proximity to the steel sheet, the diffusion layer having a thickness of 10 μm or less; a surface coating layer provided on a surface of the intermetallic compound layer, the surface coating layer including a coating containing ZnO and a zinc phosphate coating and having a surface roughness of 3 μm or more and 20 μm or less as a maximum profile height Rt in accordance with JIS B0601 (2001); and an electrodeposition paint film provided on a surface of the surface coating layer and having a thickness of 6 μm or more and less than 15 μm.

22 . The automobile part according to claim 21 , wherein the maximum profile height Rt is 7 μm or more and 14 μm or less.

23 . The automobile part according to claim 21 , wherein the ZnO has an average grain size of 50 nm or more and 1000 nm or less in diameter.

24 . The automobile part according to claim 21 , wherein a content of ZnO is 0.3 g/m 2 or more and 3 g/m 2 or less in metallic Zn equivalent for one surface.

25 . The automobile part according to claim 23 , wherein a content of ZnO is 0.3 g/m 2 or more and 3 g/m 2 or less in metallic Zn equivalent for one surface.

26 . The automobile part according to claim 21 , wherein the steel sheet is an Al plated steel sheet having an Al plating layer formed on a surface of the steel sheet serving as a base metal.

27 . The automobile part according to claim 25 , wherein the Al plating layer has an average primary crystal diameter of 4 μm or more and 40 μm or less.

28 . The automobile part according to claim 25 , wherein an amount of the Al plating layer is 30 g/m 2 or more and 110 g/m 2 or less for one surface.

29 . The automobile part according to claim 27 , wherein an amount of the Al plating layer is 30 g/m 2 or more and 110 g/m 2 or less for one surface.

30 . A method for manufacturing an automobile part, the method comprising:
using an Al plated steel sheet including a coating containing ZnO on a surface of the Al plated steel sheet; using a hot pressing method; causing an Al plating layer having an average primary crystal diameter of 4 μm or more and 40 μm or less to have an amount of plating of 30 g/m 2 or more and 110 g/m 2 or less for one surface; causing a ZnO amount of the Al plating layer to be 0.3 g/m 2 or more and 3 g/m 2 or less in metallic Zn equivalent for one surface; causing a rate of temperature increase during a heating process in hot pressing to be 12° C./second or more; causing a reaching steel sheet temperature to be 870° C. or more and 1100° C. or less; and causing a electrodeposition paint film to have thickness of 6 μm or more and less than 15 μm.

31 . The method for manufacturing an automobile part according to claim 30 , wherein an amount of the Al plating layer is 50 g/m 2 or more and 80 g/m 2 or less for one surface.

32 . A method for manufacturing a high-strength automobile part, the method comprising:
using an Al plated steel sheet including a coating containing ZnO on a surface of the Al plated steel sheet; using a hot pressing method; causing an Al plating layer having an average primary crystal diameter of 4 μm or more and 40 μm or less to have an amount of plating of 30 g/m 2 or more and less than 60 g/m 2 for one surface; causing a ZnO amount of the Al plating layer to be 0.3 g/m 2 or more and 3 g/m 2 or less as metallic Zn for one surface; causing a rate of temperature increase during a heating process in hot pressing to be less than 12° C./second; causing a reaching steel sheet temperature to be 850° C. or more and 950° C. or less; and causing a electrodeposition paint film to have thickness of 6 μm or more and less than 15 μm.

33 . The method for manufacturing an automobile part according to claim 31 , wherein an amount of the Al plating layer is 35 g/m 2 or more and 55 g/m 2 or less for one surface.

34 . A method for manufacturing a high-strength automobile part, the method comprising:
using an Al plated steel sheet including a coating containing ZnO on a surface of the Al plated steel sheet; using a hot pressing method; causing an Al plating layer having an average primary crystal diameter of 4 μm or more and 40 μm or less to have an amount of plating of 60 g/m 2 or more and 110 g/m 2 or less for one surface; causing a ZnO amount of the Al plating layer to be 0.3 g/m 2 or more and 3 g/m 2 or less as metallic Zn for one surface; causing a rate of temperature increase during a heating process in hot pressing to be less than 12° C./second; causing a reaching steel sheet temperature to be 920° C. or more and 970° C. or less; and causing a electrodeposition paint film to have thickness of 6 μm or more and less than 15 μm.

35 . The method for manufacturing an automobile part according to claim 34 , wherein an amount of the Al plating layer is 60 g/m 2 or more and 90 g/m 2 or less for one surface.

36 . The method for manufacturing an automobile part according to claim 30 , wherein the content of ZnO is 0.5 g/m 2 or more and 1.5 g/m 2 or less in metallic Zn equivalent for one surface.

37 . The method for manufacturing an automobile part according to claim 32 , wherein the content of ZnO is 0.5 g/m 2 or more and 1.5 g/m 2 or less in metallic Zn equivalent for one surface.

38 . The method for manufacturing an automobile part according to claim 34 , wherein the content of ZnO is 0.5 g/m 2 or more and 1.5 g/m 2 or less in metallic Zn equivalent for one surface.

39 . The method for manufacturing an automobile part according to claim 30 , wherein the Al plating layer has an average primary crystal diameter of 4 μm or more and 30 μm or less.

40 . The method for manufacturing an automobile part according to claim 32 , wherein the Al plating layer has an average primary crystal diameter of 4 μm or more and 30 μm or less.

41 . The method for manufacturing an automobile part according to claim 34 , wherein the Al plating layer has an average primary crystal diameter of 4 μm or more and 30 μm or less.

42 . The method for manufacturing an automobile part according to claim 30 , further comprising:
treating the Al plated steel sheet with chemical conversion by using a chemical conversion liquid containing phosphates, before hot pressing.

43 . The method for manufacturing an automobile part according to claim 32 , further comprising:
treating the Al plated steel sheet with chemical conversion by using a chemical conversion liquid containing phosphates, before hot pressing.

44 . The method for manufacturing an automobile part according to claim 34 , further comprising:
treating the Al plated steel sheet with chemical conversion by using a chemical conversion liquid containing phosphates, before hot pressing.

Assignees

• Nippon Steel & Sumitomo Metal Corp

Inventors

• Maki Jun
• Yamanaka Shintaro
• Irikawa Hideaki

Classifications

• C23C28/32

  including at least one pure metallic layer · CPC title

• C21D8/0478

  involving a particular surface treatment (C21D8/0494 takes precedence) · CPC title

• C22C38/002

  containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60 · CPC title

• C25D13/20

  Pretreatment · CPC title

• C21D9/48

  deep-drawing sheets · CPC title