Gray cast iron for manufacturing brake discs and brake discs for disc brakes having braking surfaces made of said gray cast iron

Abstract

The present invention provides a gray cast iron comprising carbon, silicon, vanadium, manganese, nickel, chromium, molybdenum, copper, sulfur, phosphorus, tin, and titanium, wherein the weight percent of carbon is 3.70 to 3.90 percent, the weight percent of silicon is 1.30 to 2.10 percent, the weight percent of vanadium is 0.10 to 0.15 percent, the weight percent of manganese is 0.60 to 0.90 percent, the weight percent of nickel is 0.05 to 0.5 percent; the weight percent of chromium is 0.20 to 0.35 percent; the weight percent of molybdenum is 0.10 percent or less; the weight percent of copper is 0.35 percent or less; the weight percent of sulfur is 0.10 percent or less; the weight percent of phosphorus is 0.10 percent or less; the weight percent of tin is 0.10 percent or less; the weight percent of titanium is 0.01 percent or less; and the balance is iron.

Description

[Technical Field]

[0001] The present invention relates in particular to a cast iron for manufacturing brake discs, and to a brake disc for a disc brake using said cast iron. [Background technology]

[0002] As is well known, the brake band of a gray cast iron brake disc will wear out over time, which inevitably affects the lifespan of the disc.

[0003] Therefore, there is a great need to manufacture cast iron brake discs with high wear resistance in the automotive sector, especially in high performance vehicles.

[0004] Improved wear resistance leads to reduced metal dust released into the environment.

[0005] However, to improve the wear resistance of gray cast iron discs, it is necessary to take into account the high mechanical and thermal stresses to which brake discs are subjected, which can lead to high temperatures in the brake band, which can lead to a decrease in braking performance and even the formation of cracks in the brake band.

[0006] Furthermore, it is considered necessary for gray cast iron brake discs to have high corrosion resistance in order to enhance their durability, and therefore, the improvement of wear resistance must not adversely affect corrosion resistance.

[0007] No grey cast iron solution is known in the art that can simultaneously combine high wear resistance with high performance such as mechanical resistance, heat resistance and corrosion resistance. Summary of the Invention

[0008] The object of the present invention is to overcome the drawbacks mentioned with reference to the prior art. For the manufacture of ブレーキディスク To provide gray cast iron.

[0009] This drawback is overcome by the grey cast iron according to claim 1.

[0010] Further embodiments of the cast iron according to the invention are set forth in the following claims.

[0011] Further features and advantages of the present invention will become more apparent from the description given below of preferred, non-limiting embodiments thereof. DETAILED DESCRIPTION OF THE INVENTION

[0012] According to a typical embodiment, the gray cast iron for manufacturing brake discs of the present invention contains in the alloy: carbon, シリコン , vanadium, manganese, nickel, chromium, molybdenum, copper, sulfur, phosphorus, tin and titanium.

[0013] These alloy elements are contained so that their mass ratios relative to the total mass of the cast iron fall within the following ranges. - Carbon 3.70 to 3.90 mass percent. - シリコン 1.30 to 2.10 mass percent. - Vanadium 0.10 to 0.15 mass percent. - Manganese 0.60 to 0.90 mass percent. - Nickel 0.05-0.50 mass percent. - Chromium 0.20-0.35 mass percent. - Molybdenum not exceeding 0.10 mass percent. - Copper not exceeding 0.35 percent by weight. - Sulfur less than 0.10 percent by mass. - Phosphorus less than 0.10 percent by weight. - Less than 0.10 percent by weight of tin. - Titanium not exceeding 0.01 percent by mass. The remaining mass is iron.

[0014] Preferably, carbon quality The percentages are 3.70 and 3.86 percent.

[0015] Preferably, silicon quality The percentage ranges from 1.40 to 2.08 percent.

[0016] Preferably, vanadium quality The percentage is between 0.12 and 0.14 percent.

[0017] Preferably, manganese quality The percentage ranges from 0.63 to 0.85 percent.

[0018] Preferably, nickel quality The percentages range from 0.06 to 0.47 percent.

[0019] Preferably, chromium quality The percentage ranges from 0.21 to 0.35 percent.

[0020] Preferably, copper quality The percentage ranges from 0.19 to 0.35 percent.

[0021] Preferably, tin quality The percentage is less than 0.09 percent.

[0022] Preferably, titanium quality The percentage ranges from 0.0079 to 0.01 percent.

[0023] According to a first preferred embodiment, For the manufacture of ブレーキディスク Gray cast iron has the following composition: - Carbon 3.86 quality percent. - Silicone 1.85 quality percent. - Vanadium 0.12 quality percent. - Manganese 0.63 quality percent. - Nickel 0.06 quality percent. - Chrome 0.21 quality percent. - Molybdenum 0.002 quality percent. - Copper 0.19 quality percent. - Sulfur 0.065 quality percent. - Phosphorus 0.04 quality percent. - Tin 0.023 quality percent. - Titanium 0.0079 quality percent. The rest quality is iron.

[0024] According to a second preferred embodiment, For the manufacture of ブレーキディスク Gray cast iron has the following composition: - Carbon 3.70 quality percent. - Silicon 2.08 quality percent. - Vanadium 0.12 quality percent. - Manganese 0.658 quality percent. - Nickel 0.47 quality percent. - Chromium 0.255 quality percent. - Molybdenum 0.0312 quality percent. - Copper 0.238 quality percent. - Sulfur 0.0463 quality percent. - Phosphorus 0.031 quality percent. - Tin 0.038 quality percent. - Titanium 0.01 quality percent. The rest quality is iron.

[0025] Advantageously, For the manufacture of ブレーキディスクGray cast iron is equal to 0.10 to 0.14 percent, preferably 0.12 percent quality It may further contain tungsten in percentage.

[0026] According to a third particularly preferred embodiment, For the manufacture of ブレーキディスク Gray cast iron has the following composition: - Carbon 3.75 quality percent. - Silicone 1.40 quality percent. - Vanadium 0.14 quality percent. - Tungsten 0.12 quality percent. - Manganese 0.85 quality percent. - Nickel 0.1 quality percent. - Chromium 0.35 quality percent. - Molybdenum 0.1 quality percent. - Copper 0.35 quality percent. - Sulfur 0.1 quality Less than percent. - Phosphorus 0.1 quality Less than percent. - Tin 0.09 quality percent. - Titanium 0.01 quality percent. The rest quality is iron.

[0027] Preferably, the iron-based matrix of the cast iron is of the pearlitic or fine lamellar type. quality of pearlite against quality The percentage is over 95 percent.

[0028] Preferably, the gray cast iron has an iron matrix quality Less than 5 percent of qualitypercent of ferrite. More preferably, the iron matrix quality of ferrite against quality Percent equals 1 percent.

[0029] In particular, gray cast iron has an iron matrix quality Less than 1 percent of quality percent cementite and free carbides.

[0030] Advantageously, the cast iron of the present invention can be used to manufacture components for disc brakes.

[0031] For example, cast iron can be used to manufacture at least one brake band of a brake disc for any type of disc brake.

[0032] Experimental wear tests were carried out comparing brake discs made from grey cast iron of standard composition with brake discs made from three cast irons with three different compositions according to the invention.

[0033] Brake discs were obtained using grey cast iron with the following composition: 3.74 mass percent carbon; シリコン 1.65 percent by mass; manganese 0.55 percent by mass; nickel 0.1 percent by mass; chromium 0.15 percent by mass; molybdenum 0.1 percent by mass; copper 0.2 percent by mass; sulfur less than 0.1 percent by mass; phosphorus less than 0.08 percent by mass; tin 0.023 percent by mass; titanium 0.09 percent by mass; the remainder by mass being iron.

[0034] The iron-based matrix is quality percent ferrite, 98.5 quality percent perlite and 0.5 quality percent carbides.

[0035] Such a brake disc made of grey cast iron will be referred to hereinafter as a comparative disc. [Example]

[0036] A first brake disc was obtained, identical to the comparative disc, but using grey cast iron according to the invention and having a first composition: 3.86 mass percent carbon; シリコン 1.85 percent by mass; vanadium 0.12 percent by mass; manganese 0.63 percent by mass; nickel 0.06 percent by mass; chromium 0.21 percent by mass; molybdenum 0.002 percent by mass; copper 0.19 percent by mass; sulfur 0.065 percent by mass; phosphorus 0.04 percent by mass; tin 0.023 percent by mass; titanium 0.0079 percent by mass; the balance being iron.

[0037] The iron-based matrix is quality percent ferrite, 98 quality percent perlite, 1 quality percent carbides.

[0038] Hereinafter, such a brake disc made of gray cast iron will be referred to as disc 1. [Example]

[0039] A second brake disc was obtained, identical to the comparative disc, but using grey cast iron according to the invention and having a second composition: carbon 3.70 quality Percent silicon 2.08 quality Percentage: Vanadium 0.12 quality Percentage: Manganese 0.658 quality Percentage: Nickel 0.47 quality Percentage: Chromium 0.255 quality Percentage: Molybdenum 0.0312 quality Percentage of copper: 0.238 quality Percentage; Sulfur 0.0463 quality Percentage: Phosphorus 0.031 quality Percentage: Tin 0.038 quality Percentage: Titanium 0.01 quality percent; the remainder is iron.

[0040] The iron-based matrix is quality percent ferrite, 98 quality percent perlite, 1 quality It is composed of % carbides.

[0041] Hereinafter, such a brake disc made of gray cast iron will be referred to as disc 2. [Example]

[0042] A third brake disc was obtained, identical to the comparative disc, but using grey cast iron according to the invention and having the following third composition: 3.75 mass percent carbon; シリコン 1.40% by mass; vanadium 0.14% by mass; tungsten 0.12% by mass; manganese 0.85% by mass; nickel 0.1% by mass; chromium 0.35% by mass; molybdenum 0.1% by mass; copper 0.35% by mass; sulfur less than 0.1% by mass; phosphorus less than 0.1% by mass; tin 0.09% by mass; titanium 0.01% by mass; the remainder is iron.

[0043] The iron-based matrix is ​​approximately 1 quality percent ferrite, 97.5 quality percent perlite and 1 quality It consists of less than 100% carbides.

[0044] Hereinafter, such a brake disc made of gray cast iron will be referred to as disc 3.

[0045] Demonstration experiment

[0046] The comparative brake disc and three brake discs according to the invention (Discs 1, 2 and 3) were subjected to five repetitions of a technical test well known in the field of braking systems. At the end of such tests, the three discs quality Loss reduction emerged as 50-55 percent compared to the reference disc.

[0047] From such tests, it can be seen that under equal conditions, the brake discs according to the invention (discs 1, 2 and 3) exhibited the same wear as the comparative discs. quality significantly smaller than the loss quality On average, the brake discs according to the invention (discs 1, 2 and 3) experienced losses of less than 50 percent compared to those of the comparative discs. quality Had a loss.

[0048] This means that the grey cast iron according to the invention offers greater wear resistance than the standard grey cast iron taken as reference.

[0049] From the analysis of the test results, the disc 3 is better than the comparison disc. quality It was also found that the loss reduction was significant, which shows that the grey cast iron used to manufacture such discs 3 allows for a significantly greater wear resistance.

[0050] The same brake discs (comparison disc, disc 1, disc 2 and disc 3) were further characterized from a mechanical point of view and functional parameters, the results of which are shown in Table 1.

[0051] [Table 1]

[0052] A comparison of the data shown in Table 1 shows that the performance of discs 1, 2 and 3 in terms of mechanical resistance, heat resistance and corrosion resistance is substantially equivalent to that of brake discs made from standard grey cast iron.

[0053] All this means that, in relation to the standard grey cast iron used to manufacture the comparative discs, the grey cast iron according to the invention contains less carbon (graphite), シリコン This is also indirectly confirmed by the fact that the mass percentages of chromium and molybdenum are not significantly changed, and the sum of the mass percentages of chromium and molybdenum is not significantly changed.

[0054] Due to the high amount of carbon (graphite), the cast iron according to the invention has a high thermal conductivity, which allows for a high heat exchange during braking shocks. This significantly reduces the risk of cracks due to thermal stresses, even after heavy use of the braking system. The cast iron according to the invention also has a high damping capacity, which contributes to an increased resistance to crack formation and propagation.

[0055] The cast iron of the present invention シリコン This ratio provides a graphitization effect and can prevent the formation of cementite and carbides.

[0056] Additionally, chromium and molybdenum stabilize the formation of lamellar pearlite in the metal matrix.

[0057] At the end of five repetitions of the standard test used during the design of brake discs suitable for braking systems, the comparison disc and the pads used in conjunction with discs 1, 2 and 3 quality The losses were then also measured.

[0058] From the data comparison, it emerged that discs 1, 2 and 3 caused pad wear that was substantially equivalent to the wear caused by the comparative discs. Thus, the increased wear resistance did not cause increased pad wear relative to discs made using the cast iron according to the present invention.

[0059] As can be seen from the description, the grey cast iron of the present invention makes it possible to overcome the drawbacks presented in the prior art.

[0060] In particular, the cast iron according to the invention and the associated brake discs made from said cast iron offer significantly greater wear resistance than the standard grey cast iron taken as reference, such an increase not resulting in a deterioration of mechanical, heat and corrosion resistance.

[0061] In fact, the performance of the brake discs made of grey cast iron according to the invention is comparable to that of brake discs made of standard grey cast iron in terms of mechanical resistance, heat resistance and corrosion resistance.

[0062] It has also been found that the improved wear resistance ensured by the grey cast iron of the present invention does not significantly alter the wear of the pads. quality From the data obtained from the losses, it can be seen that the pads associated with discs 1, 2 and 3 performed substantially better than the pads associated with the comparison disc. quality It emerged that the two discs wear in a similar way (in terms of wear loss). In particular, a reduction in pad wear can actually be seen in the case of disc 3 compared to the comparison disc.

[0063] To meet specific contingency needs, those skilled in the art can make several modifications and variations to the cast iron and brake discs described above, all of which are within the scope of the present invention as defined by the following claims.

Claims

1. 1. A gray cast iron for brake disc manufacturing, comprising carbon, silicon, vanadium, manganese, nickel, chromium, molybdenum, copper, sulfur, phosphorus, tin and titanium, wherein - carbon mass percent 3.70 to 3.90, - silicon mass percentage between 1.30 and 2.10, - vanadium mass percentage of 0.10 to 0.15, - manganese mass percentage of 0.60 to 0.90, - nickel mass percentage of 0.05 to 0.50, - chromium mass percentage between 0.20 and 0.35, - the mass percentage of molybdenum is not more than 0.10; - copper mass percentage not exceeding 0.35, - a sulfur mass percentage of less than 0.10; - a mass percentage of phosphorus of less than 0.10; - tin mass percentage less than 0.10, - titanium mass percentage less than 0.01, The remaining mass is made up of iron, grey cast iron for brake disc manufacturing.

2. 2. Gray cast iron for manufacturing brake discs according to claim 1, characterized in that the mass percentage of carbon is between 3.70 and 3.86 percent.

3. 3. Gray cast iron for manufacturing brake discs according to claim 1 or 2, wherein the mass percentage of silicon is between 1.40% and 2.08%.

4. 4. Grey cast iron for manufacturing brake discs according to claim 1, wherein the mass percentage of vanadium is between 0.12 and 0.14 percent.

5. 5. Grey cast iron for manufacturing brake discs according to claim 1, wherein the mass percentage of manganese is between 0.63 and 0.85 percent.

6. 6. Grey cast iron for manufacturing brake discs according to claim 1, characterized in that the mass percentage of nickel is between 0.06 and 0.47%.

7. 7. Grey cast iron for manufacturing brake discs according to claim 1, characterized in that the mass percentage of chromium is between 0.21 and 0.35%.

8. 8. Grey cast iron for manufacturing brake discs according to claim 1, characterized in that the mass percentage of copper is between 0.19 and 0.35%.

9. 9. Grey cast iron for manufacturing brake discs according to claim 1, wherein the mass percentage of tin is less than or equal to 0.09 mass percent.

10. 10. Grey cast iron for manufacturing brake discs according to claim 1, characterized in that the mass percentage of titanium is between 0.0079 and 0.01 percent.

11. 11. Grey cast iron for manufacturing brake discs according to claim 1, having 3.86 mass percent carbon, 1.85 mass percent silicon, 0.12 mass percent vanadium, 0.63 mass percent manganese, 0.06 mass percent nickel, 0.21 mass percent chromium, 0.002 mass percent molybdenum, 0.19 mass percent copper, 0.065 mass percent sulfur, 0.04 mass percent phosphorus, 0.023 mass percent tin, 0.0079 mass percent titanium, the remainder by weight being iron.

12. 11. Grey cast iron for manufacturing brake discs according to claim 1, having 3.70% by weight of carbon, 2.08% by weight of silicon, 0.12% by weight of vanadium, 0.658% by weight of manganese, 0.47% by weight of nickel, 0.255% by weight of chromium, 0.0312% by weight of molybdenum, 0.238% by weight of copper, 0.0463% by weight of sulfur, 0.031% by weight of phosphorus, 0.038% by weight of tin, less than 0.01% by weight of titanium, the remainder being iron.

13. 11. Grey cast iron for manufacturing brake discs according to any one of claims 1 to 10, further comprising tungsten, the mass percentage of tungsten being between 0.10 and 0.

14.

14. 14. Gray cast iron for manufacturing brake discs according to claim 13, comprising 3.75 mass percent carbon, 1.40 mass percent silicon, 0.14 mass percent vanadium, 0.12 mass percent tungsten, 0.85 mass percent manganese, 0.1 mass percent nickel, 0.35 mass percent chromium, 0.1 mass percent molybdenum, 0.35 mass percent copper, less than 0.1 mass percent sulfur, less than 0.1 mass percent phosphorus, 0.09 mass percent tin, less than 0.01 mass percent titanium, the remainder being iron.

15. 15. A grey cast iron for manufacturing brake discs according to any one of claims 1 to 14, wherein the matrix of the grey cast iron is pearlitic and the mass percentage of pearlite relative to the mass of the matrix of the grey cast iron is 95% or more.

16. 16. A grey cast iron for manufacturing brake discs according to claim 1, comprising ferrite in a mass percentage lower than 5 percent relative to the mass of the matrix of said grey cast iron.

17. A gray cast iron for manufacturing brake discs according to any one of claims 1 to 16, comprising cementite and free carbides in a mass percentage of less than 1 percent relative to the mass of the matrix of said gray cast iron.

18. A brake disc for a disc brake, comprising a braking surface made of grey cast iron according to any one of claims 1 to 17.

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