TRACK LINK PRODUCTION METHOD

Abstract

The present disclosure refers to a method for manufacturing a track link for a running gear of a tracked vehicle, comprising the following method steps: P1) providing a forging blank of steel, P2) hot forging the forging blank to produce a track link blank and hot trimming of the track link blank to form at least a wheel tread part of the track link blank, P3) quenching the track link blank to a temperature T1, P4) low temperature tempering the track link blank at a temperature of 20050 C., and P5) finish machining the tempered track link blank to produce the final shape of the track link.

Claims

1.-5. (canceled)

6. A method for manufacturing a track link for a running gear of a tracked vehicle, the method comprising: P1) providing a forging blank of steel; P2) hot forging the forging blank to produce a track link blank and hot trimming of the track link blank to form at least a wheel tread part of the track link blank; P3) quenching the track link blank to a temperature T1, wherein a starting temperature for the quenching of the track link blank in step P3) is 88010 C. and the temperature T1 is a temperature in the range between 235 C. and 190 C.; P4) low temperature tempering the track link blank at a temperature of 20050 C.; P5) finish machining the tempered track link blank to produce the final shape of the track link; and wherein the steel of the forging blank has the following composition (in % by weight): 0.25-0.33% Carbon (C), 0.75-1.05% Manganese (Mn), 0.15-0.35% Silicon (Si), 0.75-0.85% Molybdenum (Mo), 0.65-0.95% Chromium (Cr), 0.65-0.95% Nickel (Ni), 0.02-0.05% Niobium (Nb), and up to a maximum of 0.015% Phosporus (P), the balance being iron and unavoidable impurities.

7. The method of claim 6, wherein the steel further comprises: up to a maximum of 0.005% Sulphur(S).

8. The method of claim 7, wherein the steel further comprises: up to a maximum of 0.2% Copper (Cu).

9. The method of claim 8, wherein the steel further comprises: up to a maximum of 0.005% Calcium (Ca).

10. The method of claim 6, wherein the quenching in process step P3) comprises a reheating of the track link blank up to a temperature of 88010 C., and a rapid cooling of the reheated track link blank to a temperature T1 between 190 C. and 235 C.

11. The method of claim 10, wherein the reheating includes heating the track link blank from 20 C. up to 879 C. at an average temperature rate of 7.7 C./min.

12. A track link for a running gear of a tracked vehicle obtainable by a production process according to claim 6, wherein the track link material has: a surface hardness of >44 HRC; a core hardness of >44 HRC; a tensile strength of >1.500 MPa; and a toughness of at least 20 J at 45 C.

13. The track link of claim 12, wherein the track link material has a yield strength R.sub.p0,2 of >1.100 MPa.

Description

[0048] The invention is described in more detail with the help of the FIGURE. The only FIGURE shows schematically the process steps of the production method according to the invention.

[0049] FIG. 1 shows the process steps of the production method according to the present invention. In process step P1) there is provided a forging blank made out of steel. In process step P2) the forging blank is hot forged to produce a track link blank, and the track link blank is hot trimmed to form a wheel tread part of the track link blank.

[0050] In process step P3) the track link blank is quenched to a temperature T1. The starting temperature for the quenching of the track link blank is 88010 C. The temperature T1 is a temperature in the range between 235 C. and 190 C.

[0051] If the track link blank is within the temperature range of 88010 C. after the process step P2) has been finished, then the track link blank can be quenched immediately after completion of process step P2). But according to the present invention it is also possible to allow the track link blank to cool down to a temperature below 880-10 C. after process step P2). The track link blank may be allowed, for example, to cool down to room temperature after process step P2). In this way, the process steps P2) and P3) can be separated from one another, i.e. the process step P3) can be carried out at a later point in time independently of process step P2) and at a place different from the place where process step P2) was carried out.

[0052] If the track link blank is allowed to cool down to a temperature below 880-10 C., then the process step P3) comprises a reheating of the track link blank to a temperature in the range of 88010 C. prior to quenching.

[0053] The quenching in process step P3) comprises a rapid cooling of the reheated track link blank to a temperature T1 between 235 C. and 190 C.

[0054] According to an embodiment of the present invention, the reheating in process step P3) includes heating the track link blank from 20 C. up to 879 C., e.g. at an average heating rate between 7 and 8 C./min, for example at a heating rate of 7.7 C./min. The mentioned heating rate and the mentioned heating temperature have proven to produce good results when used with a steel composition according to the present invention.

[0055] In the process step P4) the track link blank is subjected to a low temperature tempering at a temperature of approximately 200 C. for a period of time of 260 minutes.

[0056] In the process step P5) the tempered track link blank is subjected to a finish machining in order to produce the final shape of the track link. [0057] According to the present invention, the described manufacturing process is carried out on a forging blank comprising the following composition (in % by weight): [0058] 0.25-0.33% Carbon (C), [0059] 0.75-1.05% Manganese (Mn), [0060] 0.15-0.35% Silicon (Si), [0061] 0.75-0.85% Molybdenum (Mo), [0062] 0.65-0.95% Chromium (Cr), [0063] 0.65-0.95% Nickel (Ni), [0064] 0.02-0.05% Niobium (Nb), [0065] optionally up to a maximum of 0.015% Phosporus (P), [0066] optionally up to a maximum of 0.005% Sulphur(S), [0067] optionally up to a maximum of 0.2% Copper (Cu), [0068] optionally up to a maximum of 0.005% Calcium (Ca),
the balance being iron and unavoidable impurities.

[0069] The described manufacturing process leads to a track link having very good mechanical properties, including (in combination with each other) a surface hardness of >44 HRC, a core hardness of >44 HRC, a tensile strength of >1.500 MPa, and a toughness of at least 20 J at 45 C. Due to the high value of surface and core hardness, the track link according to the invention features a very god wear resistance. The high value of tensile strength of the track link material leads to a very good resistance of the track link against deformation under heavy loads. Due to the high toughness of the track link material, the track link has a high resistance to cracking, especially in the pin hole and bushing hole areas.

[0070] Thus, the present invention provides a track link that has a particularly long service life, while at the same time being inexpensive to manufacture.