Iron alloy and part for a motor vehicle comprising said alloy

Abstract

The present invention relates to an iron alloy comprising, in wt %: C ranging from 3.1 to 3.9; Si ranging from 1.8 to 2.8; Mn ranging from 0.5 to 0.9; V ranging from 0.2 to 0.6; Mo ≤ 0.7; Cu < 0.6; Cr ≤ 0.35; Ni < 0.2; S < 0.15; P < 0.1; Sn < 0.1; iron and unavoidable impurities.

Description

[0001] DESCRIPTION

[0002] TITLE: Iron alloy and motor vehicle part comprising said alloy

[0003] Technical field

[0004] The present invention relates generally to iron alloys, in particular iron alloys intended to be integrated into a motor vehicle.

[0005] In particular, the invention relates to a specific iron alloy, a part for a motor vehicle comprising said iron alloy and a motor vehicle comprising said part.

[0006] State of the art

[0007] When the brake rotor and brake pad come into contact during braking, fine particles are emitted. These particles from braking are harmful to health and are the subject of special attention by the European Commission.

[0008] More specifically, particles from braking come from the wear of the brake rotor track and the brake pad in contact with each other.

[0009] Currently, brake rotors are made of cast iron, a material that is a specific iron alloy. This material leads to high emissions of fine particles, which is the origin of the work of the European Commission.

[0010] Brake track wear can depend on the hardness of the brake rotor material. The harder the material, the more durable it is and the less wear there is on the brake rotor track. Less wear results in less particle emissions from braking.

[0011] Various avenues have been explored to improve the hardness of this material. Strengthening the material by applying an additional coating has been studied. While this does improve the surface hardness of the material, the associated cost is extremely high. The investments are significant and generate additional costs for the part to be developed. Thus, there is a need for iron alloys with improved hardness and wear resistance.

[0012] Statement of the invention

[0013] The invention therefore aims to provide an iron alloy having improved hardness and improved wear.

[0014] The invention therefore relates to an iron alloy comprising, in % by weight:

[0015] C ranging from 3.1 to 3.9;

[0016] If ranging from 1.8 to 2.8;

[0017] Mn ranging from 0.5 to 0.9;

[0018] V ranging from 0.2 to 0.6;

[0019] Mo < 0.7;

[0020] Cu < 0.6;

[0021] Cr < 0.35;

[0022] Ni < 0.2;

[0023] S < 0.15;

[0024] P < 0.1;

[0025] Sn < 0.1; iron and unavoidable impurities.

[0026] In the iron alloy according to the invention, the weight percentages (wt%) are defined relative to the total weight of the iron alloy.

[0027] The present invention also relates to a part for a motor vehicle, such as a brake rotor, comprising at least one iron alloy according to the invention.

[0028] Another subject of the invention is a motor vehicle comprising at least one motor vehicle part according to the invention.

[0029] Thanks to the iron alloy according to the invention, an improvement in hardness and a reduction in wear are obtained.

[0030] Other characteristics, aspects, objects and advantages will emerge from the description which follows and from the following examples, given for purely illustrative purposes.

[0031] For the purposes of the present invention, the expression "at least one" used is equivalent to the expression "one or more". In addition, the limits of a domain of values ​​are included in this domain, in particular in the expressions "between ... and ..." and "... from ... to ...", unless specifically mentioned.

[0032] Furthermore, it is understood by "<" strictly less than. For example, Ni < 0.2 means that the nickel content is strictly less than 0.2% by weight relative to the total weight of the iron alloy. Furthermore, it is understood by "<" less than or equal to. For example, Cr < 0.35 means that the chromium content is less than or equal to 0.35% by weight relative to the total weight of the iron alloy.

[0033] Thus, for the purposes of the present invention, the expression "... from ... to < ..." is understood to mean that the lower limit of the range of values ​​is included in the range but that the upper limit is excluded from the range of values. For example, "Cu ranging from 0.2 to < 0.6" means that 0.2 is included in the range and that 0.6 is excluded from the range. In other words, "Cu ranging from 0.2 to < 0.6" means that the copper content is greater than or equal to 0.2% by weight and strictly less than 0.6% by weight relative to the total weight of the iron alloy.

[0034] For the purposes of the present invention, the term "unavoidable impurity" is understood to mean an atom, or a group of atoms, other than C, Si, Mn, V, Mo, Cu, Cr, Ni, S, P, and Sn, which is present in a content less than or equal to 0.1% by weight relative to the total weight of the iron alloy, with the exception of Zn where the content is less than or equal to 0.2% by weight relative to the total weight of the iron alloy. In other words, each unavoidable impurity is present in a content less than or equal to 0.1% by weight relative to the total weight of the iron alloy, with the exception of Zn where the content is less than or equal to 0.2% by weight relative to the total weight of the iron alloy.

[0035] As indicated previously, the present invention relates to an iron alloy as defined above.

[0036] Advantageously, all of the unavoidable impurities are present in a content less than or equal to 0.5% by weight relative to the total weight of the iron alloy. Advantageously, the iron alloy comprises at least 80% by weight of iron, preferably at least 85% by weight of iron relative to the total weight of the iron alloy.

[0037] Advantageously, the iron alloy comprises, in % by weight: Cu ranging from 0.2 to < 0.6, preferably ranging from 0.4 to < 0.6.

[0038] According to a first preferred embodiment, the iron alloy comprises, in % by weight: Cr ranging from 0.2 to 0.35.

[0039] Preferably, in this first embodiment, the iron alloy may comprise, in % by weight: V ranging from 0.2 to 0.3.

[0040] Preferably, in this first embodiment, the iron alloy may comprise, in % by weight: Mo < 0.1.

[0041] According to a preferred embodiment, the iron alloy comprises, in % by weight: Cr ranging from 0.2 to 0.35;

[0042] V ranging from 0.2 to 0.3; and

[0043] Mo < 0.1.

[0044] According to another preferred embodiment, the iron alloy comprises, in % by weight: Cu ranging from 0.2 to <0.6;

[0045] Cr ranging from 0.2 to 0.35;

[0046] V ranging from 0.2 to 0.3; and Mo < 0.1.

[0047] According to a more preferred embodiment, the iron alloy comprises, in % by weight: Cu ranging from 0.4 to <0.6;

[0048] Cr ranging from 0.2 to 0.35;

[0049] V ranging from 0.2 to 0.3; and

[0050] Mo < 0.1.

[0051] According to a second embodiment, the iron alloy comprises: in % by weight: Cr < 0.25.

[0052] Preferably, in this second embodiment, the iron alloy may comprise, in % by weight: V ranging from 0.4 to 0.6.

[0053] Preferably, in this second embodiment, the iron alloy may comprise, in % by weight: Mo ranging from 0.5 to 0.7. According to a preferred embodiment, the iron alloy comprises, in % by weight: Cr < 0.25;

[0054] V ranging from 0.4 to 0.6; and

[0055] Mo ranging from 0.5 to 0.7.

[0056] According to another preferred embodiment, the iron alloy comprises, in % by weight:

[0057] Cu ranging from 0.4 to < 0.6;

[0058] Cr < 0.25;

[0059] V ranging from 0.4 to 0.6; and

[0060] Mo ranging from 0.5 to 0.7.

[0061] Advantageously, the iron alloy consists, in % by weight:

[0062] C ranging from 3.1 to 3.9;

[0063] If ranging from 1.8 to 2.8;

[0064] Mn ranging from 0.5 to 0.9;

[0065] V ranging from 0.2 to 0.6;

[0066] Mo < 0.7;

[0067] Cu < 0.6;

[0068] Cr < 0.35;

[0069] Ni < 0.2;

[0070] S < 0.15;

[0071] P < 0.1;

[0072] Sn < 0.1; the remainder being iron and unavoidable impurities.

[0073] Another subject of the invention relates to a part for a motor vehicle, such as a brake rotor, comprising at least one iron alloy according to the invention as previously described.

[0074] The present invention also relates to a motor vehicle comprising at least one part for a motor vehicle according to the invention as previously described.

[0075] The following examples serve to illustrate the invention without, however, being limiting in nature.

[0076] EXAMPLES The iron alloys as described in Table 1 below were prepared: the contents are expressed in % by weight relative to the total weight of the iron alloy.

[0077] [Table 1]

[0078] Thus, alloy A is a comparative iron alloy. Alloys B to D are alloys according to the invention. Alloys B to D are obtained following the same production process as alloy A by adapting the melting bed to which the alloying elements of the invention (V, Mo, Cr, Cu) are added. Then, the alloys were transformed into discs with a diameter < 150 mm and a thickness < 15 mm, then characterized. The chemical composition was obtained from the spectrometric medals cast during the manufacture of the discs.

[0079] Hardness assessment

[0080] The hardness of the different alloys was evaluated in accordance with standard NF EN ISO 6506-1 of November 22, 2014. Brinell hardness is expressed in HB.

[0081] The results are collected in Table 2 below:

[0082] [Table 2]

[0083] It is clear that iron alloys B, C and D according to the invention have a significantly higher Brinell hardness than that of the comparative iron alloy A.

[0084] Therefore, the iron alloys according to the invention have improved hardness.

[0085] Wear assessment

[0086] The wear of alloys A to C was evaluated on a pin / disc bench. A brake pad material pin is brought into contact at a given pressure and linear speed on one face of an iron alloy disc. After a fixed friction time, the wear volume of the iron alloy disc track is measured and related to the friction distance to determine the wear rate in mm. 3 / km.

[0087] The results are collected in Table 3 below:

[0088] [Table 3]

[0089] It is clear that iron alloys B and C according to the invention have a significantly lower wear rate than that of comparative iron alloy A. It is noted in particular that when iron alloy C according to the invention is used, a wear rate half that of comparative iron alloy A can be observed.

[0090] Therefore, the iron alloys according to the invention exhibit improved wear behavior.

[0091] The iron alloys according to the invention therefore have improved hardness and wear, i.e. higher hardness and reduced wear. With reduced wear, the emission of particles from braking can be reduced, but also the service life of motor vehicle parts, such as a brake rotor, can be improved.

Claims

CLAIMS 1. Iron alloy comprising, in % by weight: C ranging from 3.1 to 3.9; If ranging from 1.8 to 2.8; Mn ranging from 0.5 to 0.9; V ranging from 0.2 to 0.6; Mo < 0.7; Cu < 0.6; Cr < 0.35; Ni < 0.2; S < 0.15; P < 0.1; Sn < 0.1; iron and unavoidable impurities.

2. Alloy according to claim 1, comprising at least 80% by weight of iron, preferably at least 85% by weight of iron relative to the total weight of the iron alloy.

3. Alloy according to claim 1 or 2, comprising: Cu ranging from 0.2 to < 0.6, preferably ranging from 0.4 to < 0.

6.

4. Alloy according to any one of the preceding claims, comprising: Cr ranging from 0.2 to 0.

35.

5. Alloy according to any one of the preceding claims, comprising: V ranging from 0.2 to 0.

3.

6. Alloy according to any one of the preceding claims, comprising: Mo < 0.

1.

7. Alloy according to any one of claims 1 to 3, comprising: Cr < 0.

25.

8. Alloy according to claim 7, comprising: V ranging from 0.4 to 0.

6.

9. Alloy according to claim 7 or 8, comprising: Mo ranging from 0.5 to 0.

7.

10. Part for a motor vehicle, such as a brake rotor, comprising at least one iron alloy according to any one of the preceding claims. 1 1. Motor vehicle comprising at least one motor vehicle part according to claim 10.

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