阅读说明：本技术 轨道部件和用于制造轨道部件的方法 (Rail component and method for producing a rail component ) 是由 C.卡梅尔霍夫 H.P.布兰特纳 于 2018-05-29 设计创作，主要内容包括：在轨道部件,特别是轨道运输工具用低合金钢轨道中,在所述轨道部件的轨道轨头中的钢具有5-15体积%的铁素体份额、5-20体积%奥氏体份额、5-20体积%马氏体份额和55-75体积%无碳化物的贝氏体份额。(In a rail part, in particular a low-alloy steel rail for rail vehicles, the steel in the rail head of the rail part has a ferrite fraction of 5 to 15% by volume, an austenite fraction of 5 to 20% by volume, a martensite fraction of 5 to 20% by volume and a carbide-free bainite fraction of 55 to 75% by volume.)

1. Rail component, in particular low-alloy steel rail for rail vehicles, characterized in that the steel in the rail head of the rail component has a ferrite fraction of 5 to 15% by volume, an austenite fraction of 5 to 20% by volume, a martensite fraction of 5 to 20% by volume and a carbide-free bainite fraction of 55 to 75% by volume.

2. The rail part according to claim 1, characterized in that the fraction of carbide-free bainite is 60-70 vol%.

3. Rail part according to claim 1 or 2, characterized in that the ferrite fraction is 8-13 vol-%.

4. A rail part according to claim 1, 2 or 3, characterized in that bainite forms a matrix, in which austenite, martensite and ferrite are preferably evenly distributed.

5. The rail part according to one of claims 1 to 4, characterized in that the austenite fraction and the martensite fraction are present at least partially in island form.

6. The rail component of any one of claims 1 to 5, wherein the low alloy steel comprises carbon, silicon, manganese, chromium, molybdenum and optionally vanadium, phosphorus, sulfur, boron, titanium, aluminum and/or nitrogen as alloying constituents and the remainder iron.

7. The rail member of claim 6, wherein no alloy constituent is present in a fraction greater than 1.8 wt.%.

8. The rail part according to any one of claims 1 to 7, characterized in that silicon is present in a fraction of less than 1.2 wt.%.

9. The rail part according to any one of claims 1 to 8, characterized in that carbon is present in a fraction of less than 0.6 wt.%, preferably less than 0.35 wt.%.

10. The rail component according to any one of claims 1 to 9, characterized in that a low alloy steel is used with the following approximate analysis:

0.2-0.6 wt% C

0.9-1.2 wt% Si

1.2-1.8 wt.% Mn

0.15-0.8 wt% Cr

0.01 to 0.15 wt% Mo, and optionally

0 to 0.25% by weight of V, in particular 0.01 to 0.25% by weight of V

0 to 0.016% by weight of P, in particular 0.01 to 0.016% by weight of P

0 to 0.016% by weight S, in particular 0.01 to 0.016% by weight S

And (3) the rest: iron.

11. The rail component according to any one of claims 1 to 10, characterized in that a low alloy steel is used with the following approximate analysis:

0.28-0.32 wt.% C

0.98-1.03 wt% Si

1.7-1.8 wt.% Mn

0.28-0.32 wt% Cr

0.08 to 0.13% by weight of Mo, and optionally

0 to 0.25% by weight of V, in particular 0.01 to 0.25% by weight of V

0 to 0.016% by weight of P, in particular 0.01 to 0.016% by weight of P

0 to 0.016% by weight S, in particular 0.01 to 0.016% by weight S

And (3) the rest: iron.

12. The rail component according to any one of claims 1 to 10, characterized in that a low alloy steel is used with the following approximate analysis:

0.44-0.52 wt.% C

1.05-1.17 wt% Si

1.4-1.7 wt.% Mn

0.36-0.80 wt% Cr

0.01 to 0.08 wt% Mo, and optionally

0 to 0.25% by weight of V, in particular 0.01 to 0.25% by weight of V

0 to 0.016% by weight of P, in particular 0.01 to 0.016% by weight of P

0 to 0.016% by weight S, in particular 0.01 to 0.016% by weight S

And (3) the rest: iron.

13. The rail part as claimed in any one of claims 1 to 12, characterized in that the rail part has 1050-²Tensile strength R of_m。

14. The rail member according to any one of claims 1 to 13, wherein the rail member has a hardness of 320 and 400 HB in the rail head region.

15. Method for manufacturing a rail part according to any one of claims 1 to 14 from a hot-rolled profile, characterized in that the rail head of the rolled profile is subjected to controlled cooling immediately after leaving the rolling stand with rolling heat, wherein the controlled cooling comprises cooling under ambient air in a first step until a first temperature of 780-.

16. The method according to claim 15, wherein the accelerated cooling in the second step is performed at a cooling rate of 2-5 ℃/sec.

17. Method according to claim 15 or 16, characterized in that the third step lasts for a period of 10-300 seconds, preferably 30-60 seconds.

18. A method according to claim 15, 16 or 17, characterized in that the accelerated cooling in the fourth step is performed at a cooling rate of 2-5 ℃/sec.

19. Method according to any one of claims 15 to 18, wherein said fifth step lasts for a period of 50-600 seconds, preferably 100 and 270 seconds.

20. Method according to any of claims 15-19, wherein reheating occurs during the third and/or fifth step.

21. A method according to any one of claims 15-20, characterised by detecting the temperature at a plurality of measuring points distributed over the length of the rail part and forming a temperature average value, which is used for controlling the controlled cooling.

22. Method according to any one of claims 15 to 21, wherein the controlled cooling is performed by at least immersing the rail head in a liquid cooling medium.

23. Method according to any one of claims 15 to 22, characterized in that the cooling during the second or fourth step is controlled such that the cooling medium first forms a vapor film at the surface of the rail head and subsequently boils at said surface.

24. Method according to claim 23, characterized in that during the second and/or fourth step a rupture gaseous pressure medium, such as nitrogen, is introduced at the rail head along the entire length of the rail part to rupture the vapour film and initiate the boiling phase along the entire length of the rail part.

25. Method according to claim 24, characterized in that the status of the cooling medium is monitored during the second and/or fourth step along the entire length of the rail part and that the rupture of the membrane gaseous pressure medium is led to the rail head as soon as the first occurrence of a boiling phase is found in a partial region of the length of the rail part.

26. Method according to claim 24 or 25, characterized in that the rupture gaseous pressure medium is introduced at the rail head for about 20-100 seconds, in particular about 50 seconds, after the start of the second and/or fourth step.

27. Method according to any one of claims 15 to 26, characterized in that during the second step the rail part is completely immersed in the cooling medium.

28. Method according to any one of claims 15-27, characterized in that during the third and/or fifth step the rail part is kept in a position where it is taken out of the cooling medium.

29. Method according to any one of claims 15 to 28, characterized in that during the fourth step the rail part is immersed in the cooling medium only with the rail head.

Example 1

In a first embodiment, a low-alloy steel with the following approximate analysis is formed into a running rail with a standard rail profile by means of hot rolling:

0.3 wt% C

1.0 wt.% Si

1.74 wt.% Mn

0.31 wt% Cr

0.1 wt% Mo

0.014 wt% S

0.014 wt% P

20 ppm Al

70 ppm of nitrogen.

No alloying elements boron and titanium were added. The remainder iron and incidental accompanying elements.

Immediately after leaving the rolling stand, the rail with the rolling heat is subjected to controlled cooling. The controlled cooling is explained below with the aid of the time-temperature transition diagram shown in fig. 1, wherein the line denoted by 1 represents the cooling course. In a first step, the rail is cooled down to a temperature of 810 ℃ under ambient air. In a second step, the rail is immersed over its entire length and over its entire cross section in a liquid cooling medium, and the cooling rate is adjusted to 4 ℃/s. After about 85 seconds, the rail is removed from the cooling bath and the initial surface temperature of the rail head is measured to be 470 ℃, whereby point 2 has been reached. The rail is held in a position for removal from the cooling medium during a period of about 45 seconds. It may be reheated to a temperature of 500 c for the first 5 seconds. When point 3 is reached, the rail is again immersed in the cooling bath and cooled to 440 ℃ (point 4) at a cooling rate of 4 ℃/sec. The temperature was maintained for 100 seconds. When point 5 is reached, the rail is cooled to room temperature under ambient air.

By the above-mentioned controlled cooling, the following structure is obtained in the rail head:

60-70% by volume of carbide-free bainite,

8-13% by volume of ferrite,

11-18% by volume of austenite, the austenite being,

5-15% by volume martensite.

This organization is shown in fig. 2. The following material properties were measured:

0.2% elongation limit: 750 MPa +/-10 MPa

Tensile strength: 1130 MPa +/-10 MPa

Elongation at break: 17% +/-1%

Surface hardness: 330 HB +/-5 HB

Fracture toughness K of the standard samples at room temperature_Ic：58 MPa√m±3 MPa√m。