This invention is directed to improve a wear resistance and a damage resistance required for a rail of a sharply curved zone of a heavy load railway, comprising more than 0.85 to 1.20% of C, 0.10 to 1.00% of Si, 0.40 to 1.50% of Mn and if necessary, at least one member selected from the group consisting of Cr, Mo, V, Nb, Co and B, and retaining high temperature of hot rolling or a steel rail heated to a high temperature for the purpose of heat-treatment, the present invention provides a pearlitic steel rail having a good wear resistance and a good damage resistance, and a method of producing the same, wherein a head portion of the steel rail is acceleratedly cooled at a rate of 1° to 10° C./sec from an austenite zone temperature to a cooling stop temperature of 700° to 500° C. so that the hardness of the head portion is at least hv 320 within the range of a 20 mm depth.
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0. 24. A method for producing a pearlitic steel rail having a good wear resistance, said method comprising the steps of:
hot rolling a melted and cast steel to provide a steel rail, with said steel rail retaining rolling heat immediately after hot rolling;
cooling in an accelerated manner said steel rail retaining rolling heat immediately after hot rolling, said accelerated cooling taking place from an austenite temperature at a cooling rate of more than 10° C./sec and up to 30° C./sec.;
stopping said accelerated cooling at the point when pearlite transformation of a gage corner portion of said steel rail has proceeded at least 70% and the temperature of the rail is 700° to 500° C.; and
thereafter leaving said steel rail to cool;
wherein the hardness of said gage corner portion of said steel rail is at least hv 360 and the hardness of a head top portion is hv 250 to 320, and
wherein said steel rail comprises 0.86 to 1.20%, in terms of percent by weight of carbon, and wherein the structure of said steel rail is a pearlite, a pearlite lamella space of said pearlite is not more than 100 nm, and a ratio of a cementite thickness to a ferrite thickness in said pearlite is at least 0.15.
0. 14. A method for producing a pearlitic steel rail, having a good wear resistance, said method comprising the steps of:
hot rolling a melted and cast steel to provide a steel rail, with said steel rail retaining rolling heat immediately after hot rolling;
cooling in an accelerated manner said steel rail retaining rolling heat immediately after hot rolling, said accelerated cooling taking place from an austenite temperature at a cooling rate of more than 10° C./sec and up to 30° C./sec.;
stopping said accelerated cooling at the point when pearlite transformation of a gage corner portion of said steel rail has proceeded at least 70% and the temperature of the rail is 700° to 500° C.; and
thereafter leaving said steel rail to cool;
wherein the hardness of said gage corner portion of said steel rail is at least hv 360 and the hardness of a head top portion is hv 250 to 320, and
wherein said steel rail comprises 0.86 to 1.20%, in terms of percent by weight, of carbon, characterized in that the structure within the range of a depth of 20 mm from the surface of a rail head portion of said steel rail with said head surface being the start point is pearlite, a pearlite lamella space of said pearlite is not more than 100 nm, and a ratio of a cementite thickness to a ferrite thickness in said pearlite is at least 0.15.
0. 15. A method for producing a pearlitic steel rail, having a good wear resistance, said method comprising the steps of:
hot rolling a melted and cast steel to provide a steel rail, with said steel rail retaining rolling heat immediately after hot rolling;
cooling in an accelerated manner said steel rail retaining rolling heat immediately after hot rolling, said accelerated cooling taking place from an austenite temperature at a cooling rate of more than 10° C./sec and up to 30° C./sec.;
stopping said accelerated cooling at the point when pearlite transformation of a gage corner portion of said steel rail has proceeded at least 70% and the temperature of the rail is 700° to 500° C.; and
thereafter leaving said steel rail to cool;
wherein the hardness of said gage corner portion of said steel rail is at least hv 360 and the hardness of a head top portion is hv 250 to 320,
wherein said steel rail comprises, in terms of percent by weight:
C: 0.86 to 1.20%,
Si: 0.10 to 1.00%,
Mn: 0.40 to 1.50%, and
the balance consisting of iron and unavoidable impurities, and
wherein said steel rail characterized in that the structure of said steel rail is pearlite, a pearlite lamella space of said pearlite is not more than 100 nm, and a ratio of a cementite thickness to a ferrite thickness in said pearlite is at least 0.15. #100#
0. 20. A pearlitic steel rail, having a good weldability and a good wear resistance, wherein a structure of said steel rail is pearlite, a pearlite lamella space of said pearlite is not more than 100 nm, and a ratio of a cementite thickness to a ferrite thickness in said pearlite is at least 0.15, said steel rail comprising, in terms of percent by weight:
C: 0.86 to 1.20%,
Si: 0.10 to 1.00%,
Mn: 0.40 to 1.50%,
Cr and the balance consisting of iron and unavoidable impurities,
said chemical components Si, Cr and Mn satisfy the relation Si+Cr+Mn=1.5 to 3.0% in terms of percent by weight and wherein a head portion of said steel rail does not contain a pro-eutectic cementite structure,
wherein the hardness of a gage corner portion of said steel rail is at least hv 320 and the hardness of a head top of portion is hv 250 to 320,
and wherein said pearlitic steel rail is prepared in a process comprising:
cooling in an accelerated manner said steel rail retaining rolling heat immediately after hot rolling, said accelerated cooling taking place from an austenite temperature at a cooling rate of more than 10° to 30° C./sec;
stopping said accelerated cooling at the point when pearlite transformation of said gage corner portion of said rail has proceeded at 70% and the temperature of rail is 700° to 500° C.; and #100#
thereafter leaving said steel rail to cool.
0. 19. A pearlitic steel rail, having a good weldability and a good wear resistance, wherein a structure of said steel rail is pearlite, a pearlite lamella space of said pearlite is not more than 100 nm, and a ratio of a cementite thickness to a ferrite thickness in said pearlite is at least 0.15, said steel rail comprising, in terms of percent by weight:
C: 0.86 to 1.20%,
Si: 0.10 to 1.00%,
Mn: 0.40 to 1.50%,
Cr and the balance consisting of iron and unavoidable impurities,
said chemical components Si, Cr and Mn satisfy the relation Si+Cr+Mn=1.5 to 3.0% in terms of percent by weight and wherein a head portion of said steel rail does not contain a pro-eutectic cementite structure,
wherein the hardness of said steel rail within the range of a depth of 20 mm from the surface of a head portion of said steel rail is at least hv 320,
and wherein said pearlitic steel rail is prepared in a process comprising:
cooling in an accelerated manner said steel rail retaining rolling heat immediately after hot rolling, said accelerated cooling taking place from an austenite temperature at a cooling rate of more than 10° to 30° C./sec;
stopping said accelerated cooling at the point when pearlite transformation of a gage corner portion of said rail has proceeded at 70% and the temperature of rail is 700° to 500° C.; and
#100# thereafter leaving said steel rail to cool.
0. 16. A method for producing a pearlitic steel rail, having a good wear resistance, said method comprising the steps of:
hot rolling a melted and cast steel to provide a steel rail, with said steel rail retaining rolling heat immediately after hot rolling;
cooling in an accelerated manner said steel rail retaining rolling heat immediately after hot rolling, said accelerated cooling taking place from an austenite temperature at a cooling rate of more than 10° C./sec and up to 30° C./sec.;
stopping said accelerated cooling at the point when pearlite transformation of a gage corner portion of said steel rail has proceeded at least 70% and the temperature of the rail is 700° to 500° C.; and
thereafter leaving said steel rail to cool;
wherein the hardness of said gage corner portion of said steel rail is at least hv 360 and the hardness of a head top portion is hv 250 to 320,
wherein said steel rail comprises, in terms of percent by weight:
C: 0.86 to 1.20%,
Si: 0.10 to 1.00%,
Mn: 0.40 to 1.50%, and
the balance consisting of iron and unavoidable impurities, and
wherein said steel rail characterized in that the structure within the range of a depth of 20 mm from the surface of a rail head portion of said steel rail with said head surface being the start point is pearlite, a pearlite lamella space of said pearlite is not more than 100 nm, and a ratio of a cementite thickness to a ferrite thickness in said pearlite is at least 0.15. #100#
0. 17. A method for producing a pearlitic steel rail, having a good wear resistance, said method comprising the steps of:
hot rolling a melted and cast steel to provide a steel rail, with said steel rail retaining rolling heat immediately after hot rolling;
cooling in an accelerated manner said steel rail retaining rolling heat immediately after hot rolling, said accelerated cooling taking place from an austenite temperature at a cooling rate of more than 10° C./sec and up to 30° C./sec.;
stopping said accelerated cooling at the point when pearlite transformation of a gage corner portion of said steel rail has proceeded at least 70% and the temperature of the rail is 700° to 500° C.; and
thereafter leaving said steel rail to cool;
wherein the hardness of said gage corner portion of said steel rail is at least hv 360 and the hardness of a head top portion is hv 250 to 320,
wherein said steel rail comprises, in terms of percent by weight:
C: 0.86 to 1.20%,
Si: 0.10 to 1.00%,
Mn: 0.40 to 1.50%,
at least one member selected from the group consisting of:
Cr: 0.05 to 0.50%, #100#
Mo: 0.01 to 0.20%,
V: 0.02 to 0.30%,
Nb: 0.002 to 0.05%,
Co: 0.10 to 2.00%,
B: 0.0005 to 0.005%, and
the balance consisting of iron and unavoidable impurities, and
wherein said steel rail characterized in that the structure of said steel rail is pearlite, a pearlite lamella space in said pearlite is not more than 100 nm, and a ratio of a cementite thickness to a ferrite thickness in said pearlite is at least 0.15.
0. 18. A method for producing a pearlitic steel rail, having a good wear resistance, said method comprising the steps of:
hot rolling a melted and cast steel to provide a steel rail, with said steel rail retaining rolling heat immediately after hot rolling;
cooling in an accelerated manner said steel rail retaining rolling heat immediately after hot rolling, said accelerated cooling taking place from an austenite temperature at a cooling rate of more than 10° C./sec and up to 30° C./sec.;
stopping said accelerated cooling at the point when pearlite transformation of a gage corner portion of said steel rail has proceeded at least 70% and the temperature of the rail is 700° to 500° C.; and
thereafter leaving said steel rail to cool;
wherein the hardness of said gage corner portion of said steel rail is at least hv 360 and the hardness of a head top portion is hv 250 to 320,
wherein said steel rail comprises, in terms of percent by weight:
C: 0.86 to 1.20%,
Si: 0.10 to 1.00%,
Mn: 0.40 to 1.50%,
at least one member selected from the group consisting of:
Cr: 0.05 to 0.50%,
#100# Mo: 0.01 to 0.20%,
V: 0.02 to 0.30%,
Nb: 0.002 to 0.05%,
Co: 0.10 to 2.00%,
B: 0.0005 to 0.005%, and
the balance consisting of iron and unavoidable impurities, and
wherein said steel rail characterized in that the structure within the range of a depth of 20 mm from the surface of a rail head portion of said steel rail with said head surface being the start point is pearlite, a pearlite lamella space of said pearlite is not more than 100 nm, and a ratio of a cementite thickness to a ferrite thickness in said pearlite is at least 0.15.
0. 1. A pearlitic steel rail, having a good wear resistance, comprising more than 0.85 to 1.20%, in terms of percent by weight, of carbon, characterized in that the structure of said steel rail is a pearlite, a pearlite lamella space of said pearlite is not more than 100 nm, and a ratio of a cementite thickness to a ferrite thickness in said pearlite is at least 0.15.
0. 2. A pearlite steel rail, having a good wear resistance, comprising more than 0.85 to 1.20%, in terms of percent by weight, of carbon, characterized in that the structure within the range of a depth of 20 mm from the surface of a rail head portion of said steel rail with said head surface being the start point is pearlite, a pearlite lamella space of said pearlite is not more than 100 nm, and a ratio of a cementite thickness to a ferrite thickness in said pearlite is at least 0.15.
0. 3. A pearlite type steel rail, having a good wear resistance, comprising, in terms of percent by weight:
C: more than 0.85 to 1.20%
Si: 0.10 to 1.00%,
Mn: 0.40 to 1.50%, and
the balance consisting of iron and unavoidable impurities, said steel rail characterized in that the structure of said steel rail is pearlite, a pearlite lamella space of said pearlite is not more than 100 nm, and a ratio of a cementite thickness to a ferrite thickness in said pearlite is at least 0.15.
0. 4. A pearlitic steel rail having a good wear resistance, comprising, in terms of percent by weight:
C: more than 0.85 to 1.20%,
Si: 0.10 to 1.00%,
Mn: 0.04 to 1.50%, and
the balance consisting of iron and unavoidable impurities, said steel rail characterized in that the structure within the range of a depth of 20 mm from the surface of a rail head portion of said steel rail with said head surface being the start point is pearlite, a pearlite lamella space of said pearlite is not more than 100 nm, and a ratio of a cementite thickness to a ferrite thickness in said pearlite is at least 0.15.
0. 5. A pearlitic steel rail having a good wear resistance, comprising, in terms of percent by weight:
C: more than 0.85 to 1.20%,
Si: 0.10 to 1.00%,
Mn: 0.40 to 1.50,
at least one member selected from the group consisting of:
Cr: 0.05 to 0.50%,
Mo: 0.01 to 0.20%,
V: 0.02 to 0.30%,
Nb: 0.002 to 0.05%,
Co: 0.10 to 2.00%,
B: 0.0005 to 0.005%, and
the balance consisting of iron and unavoidable impurities,
said steel rail characterized in that the structure of said steel rail is pearlite, a pearlite lamella space in said pearlite is not more than 100 nm, and a ratio of a cementite thickness to a ferrite thickness in said pearlite structure is at least 0.15.
0. 6. A pearlitic steel rail having a good wear resistance, comprising, in terms of percent by weight:
C: more than 0.85 to 1.20%,
Si: 0.10 to 1.00%,
Mn: 0.40 to 1.50%,
at least one member selected from the group consisting of:
Cr: 0.05 to 0.50%,
Mo: 0.01 to 0.20%,
V: 0.02 to 0.30%,
Nb: 0.002 to 0.05%,
Co: 0.10 to 2.00%,
B: 0.0005 to 0.005%, and
the balance consisting of iron and unavoidable impurities,
said steel rail characterized in that the structure within the range of a depth of 20 mm from the surface of a rail head portion of said steel rail with said head surface being the start point is pearlite, a pearlite lamella space of said pearlite is not more than 100 nm, and a ratio of a cementite thickness to a ferrite thickness in said pearlite is at least 0.15.
0. 7. A pearlitic steel rail having a good weldability and a high wear resistance according to
0. 8. A pearlite type steel rail having a good weldability and a good wear resistance according to
0. 9. A method for producing a pearlitic steel rail as defined in any of
hot rolling a melted and cast steel to provide a steel rail, with said steel rail retaining rolling heat immediately after hot rolling;
cooling in an accelerated manner said steel rail retaining rolling heat immediately after hot rolling or cooling in an accelerated manner said steel rail heated for heat treatment, said accelerated cooling taking place from an austenite temperature at a cooling rate of 1° to 10° C./sec;
stopping said accelerated cooling at the point when said steel rail temperature reaches 700° to 500° C.; and
thereafter leaving said steel rail to cool;
wherein the hardness of said steel rail within the range of a depth of 20 mm from the surface of a head portion of said steel rail is at least hv 320.
0. 10. A method for producing a pearlitic steel rail as defined in any of
hot rolling a melted and cast steel to provide a steel rail, with said steel rail retaining rolling heat immediately after hot rolling;
cooling is an accelerated manner said steel rail retaining rolling heat immediately after hot rolling or cooling in an accelerated manner said steel rail heated for heat treatment, said accelerated cooling taking place from an austenite temperature at a cooling rate of more than 10° C./sec and up to 30° C./sec;
stopping said accelerated cooling at the point when pearlite transformation of said steel rail has proceeded at least 70%; and
thereafter leaving said steel rail to cool;
wherein the hardness of said steel rail within the range of a depth of 20 mm from the surface of a head portion of said steel rail is at least hv 320.
0. 11. A method for producing a pearlitic steel rail as defined in any of
hot rolling a melted and cast steel to provide a steel rail, with said steel rail retaining rolling heat immediately after hot rolling;
cooling in an accelerated manner said steel rail retaining rolling heat immediately after hot rolling or cooling in an accelerated manner said steel rail heated for heat treatment, said accelerated cooling taking place from an austenite temperature at a cooling rate of 1° to 10° C./sec;
stopping said accelerated cooling at the point when the temperature of a gage corner portion of said steel rail reaches 700° to 500° C.; and
thereafter leaving said steel rail to cool;
wherein the hardness of said gage corner portion of said steel rail is at least hv 360 and the hardness of a head top portion is hv 250 to 320.
0. 12. A method for producing a pearlitic steel rail as defined in any of
hot rolling a melted and cast steel to provide a steel rail, with said steel rail retaining rolling heat immediately after hot rolling;
cooling in an accelerated manner said steel rail retaining rolling heat immediately after hot rolling or cooling in an accelerated manner said steel rail heated for heat treatment, said accelerated cooling taking place from an austenite temperature at a cooling rate of more than 10° C./sec and up to 30° C./sec;
stopping said accelerated cooling at the point when pearlite transformation of a gage corner portion of said steel rail has proceeded at least 70%; and
thereafter leaving said steel rail to cool;
wherein the hardness of said gage corner portion of said steel rail is at least hv 360 and the hardness of a head top portion is hv 250 to 320.
0. 13. A method for producing a pearlitic steel rail as defined in
hot rolling a melted and cast steel to provide a steel rail, with said steel rail retaining rolling heat immediately after hot rolling;
cooling is an accelerated manner said steel rail retaining rolling heat immediately after hot rolling or cooling in an accelerated manner said steel rail heated for heat treatment, said accelerated cooling taking place from an austenite temperature at a cooling rate of 1° to 10° C./sec.;
stopping said accelerated cooling at the point when the temperature of said rail reaches 700° to 500° C.; and
thereafter leaving said steel rail to cool;
wherein the hardness within the range of a depth of 20 mm from the surface of a head portion of said steel rail is at least hv 320.
0. 21. The pearlitic steel rail, having a good weldability and a good wear resistance according to
Mn: 0.40 to 0.98%,
in terms of percent by weight.
0. 22. The pearlitic steel rail, having a good weldability and a good wear resistance according to
0. 23. The pearlitic steel rail, having a good weldability and a good wear resistance according to
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Table 3 shows the chemical components of the Present rail steels and the accelerated cooling condition, and Table 4 shows the chemical components of the Comparative rail steels and the accelerated cooling condition. Further, Tables 3 and 4 represent also the hardness after accelerated cooling and the measurement result of the wear amount after repetition of 700,000 times under the compulsive cooling condition by compressed air in the Nishihara type wear test shown in FIG. 7.
By the way, the rail construction is as follows.
Present rails (16 rails) Nos. 17 to 32
Heat-treated rails having the components within the range described above, and exhibiting the pearlite structure within the range of depth of at least 20 mm from the surfaces of the gage corner portion and the head top portion of the steel rails as the start point, and applied with accelerated cooling at the head portion having the hardness of at least Hv 320 in the pearlite structure within the range described above.
TABLE 3
accelerated
wear amount
cooling
hardness
of rail head
rate of head
of head
portion
chemical composition (wt %)
portion
portion
testpiece
rail
No.
C
Si
Mn
Cr
Mo
V
Nb
Co
B
(° C./sec)
(Hv)
(g/700,000 times)
rail of
17
0.86
0.49
1.48
—
0.02
—
—
—
—
4
385
0.90
this
18
0.88
0.65
1.05
—
—
—
—
0.05
—
10
391
0.86
invention
19
0.90
0.49
1.02
0.21
—
—
—
—
—
3
402
0.81
20
0.91
0.98
0.81
0.59
—
—
—
—
—
1
412
0.74
21
0.94
0.25
0.85
—
—
0.09
—
—
—
5
401
0.68
22
0.95
0.24
0.83
—
—
0.10
—
—
—
5
400
0.68
319*
23
0.94
0.26
0.86
—
—
0.08
—
—
—
5
398
0.70
275*
24
0.95
0.21
0.61
0.30
—
—
—
—
—
4
415
0.54
25
0.94
0.22
0.63
0.29
—
—
—
—
—
4
413
0.55
317*
26
0.94
0.23
0.61
0.29
—
—
—
—
—
4
410
0.57
278*
27
0.97
0.46
0.75
—
—
—
—
—
—
2
371
0.52
28
0.98
0.43
0.73
—
—
—
—
—
—
2
369
0.52
316*
29
0.97
0.45
0.75
—
—
—
—
—
—
2
368
0.54
276*
30
0.94
0.17
0.49
0.23
—
—
—
—
—
3
384
0.44
31
1.04
0.22
0.60
—
—
—
0.05
—
—
3
416
0.31
32
1.19
0.10
0.41
—
—
—
—
—
0.0010
2
421
0.21
*hardness at a point of 1 mm below a sole surface when a sol was cooled under control.
TABLE 4
accelerated
wear amount
cooling
hardness
of rail head
rate of head
of head
portion
chemical composition (wt %)
portion
portion
testpiece
rail
No.
C
Si
Mn
Cr
Mo
V
Nb
Co
B
(° C./sec)
(Hv)
(g/700,000 times)
Compara-
33
0.77
0.22
1.36
—
—
—
—
—
—
4
364
1.44
tive
34
0.78
0.54
1.30
—
—
—
—
—
—
3
368
1.40
rail steel
35
0.82
0.78
1.05
—
—
—
—
—
—
3
374
1.32
36
0.81
0.21
1.21
0.19
—
—
—
—
—
3
386
1.22
37
0.82
0.49
1.10
0.22
—
—
—
—
—
3
396
1.17
38
0.81
0.85
0.81
0.51
—
—
—
—
—
4
412
1.11
As shown in
Table 5 tabulates the chemical components, the accelerated cooling rate at the time of heat-treatment of the rails and the pearlite structure fractions at the stop of accelerated cooling of each of the present rail steels and Comparative rail steels. Further, Table 6 tabulates the hardness (Hv) of the head surface after heat-treatment of the rails and the wear amount after the Nishihara type wear test of each of the present rail steels and the Comparative rail steels. The wear test results of the rail head materials by the Nishihara type wear tester shown in
By the way, the wear testing condition are as follows.
TABLE 5
head
pearlite
portion
proportion
accelerated
at stop of
chemical composition (wt %)
cooling rate
cooling
rail
No.
C
Si
Mn
Cr
Mo
V
Nb
(° C./sec)
(%)
Present
39
0.86
0.86
1.20
28
75
rail steel
40
0.90
0.63
1.00
25
80
41
1.02
0.45
0.81
20
85
42
1.20
0.31
0.62
15
90
43
1.39
0.21
0.24
12
95
44
0.87
0.23
0.45
0.55
25
75
45
0.91
0.23
0.40
0.25
0.21
20
75
46
0.89
0.41
0.51
0.12
30
80
47
0.92
0.56
0.65
0.08
0.015
30
80
Compara-
48
0.76
0.23
0.89
25
95
tive
49
0.79
0.41
0.87
0.25
28
90
rail steel
50
0.76
0.82
0.88
0.55
15
85
51
1.50
0.23
0.85
12
*—
52
0.90
1.23
0.85
12
*65
53
0.87
0.23
1.82
12
*70
*Martensite structure and bainite structure solved into the rail head portion after cooling.
TABLE 6
hardness of
head portion
wear amount
rail
No.
(Hv)
(g/700,000 times)
Present
39
403
0.95
rail steel
40
395
0.92
41
418
0.63
42
431
0.25
43
438
0.21
44
396
0.98
45
403
0.74
46
392
0.75
47
397
0.77
Comparative
48
385
1.36
rail steel
49
391
1.25
50
393
1.23
51
580
1.56
52
371
1.35
53
395
1.31
In comparison with the eutectoid pearlite steels according to the prior art, the hypereutectoid pearlite rails according to the present invention have a higher wear resistance at the same hardness, drastically improve the wear resistance of the outer track rail of the curved zone, have a high internal fatigue damage resistance because the formation of the pro-eutectic ferrite as the start point of the internal fatigue cracks formed inside the gage corner portion of the outer track rail laid down in the sharp curve zone does not exist, and drastically improve the rail heat-treatment properties by the combination of quick accelerated cooling and the stop of cooling.
Table 7 tabulates the chemical components of each of the present rail steels and the Comparative rail steels. Table 8 tabulates the accelerated cooling rate of the rail gage corner portions, and the hardness of the gage corner portion and the head top portion.
TABLE 7
chemical composition (wt %)
rail
No.
C
Si
Mn
Cr
Mo
V
Nb
Co
B
Present
54
0.87
0.51
1.49
—
0.01
—
—
—
—
rail steel
55
0.88
0.67
1.01
—
—
—
—
0.40
—
56
0.90
0.55
0.98
0.21
—
0.07
—
—
—
57
0.91
0.99
0.78
0.58
—
—
—
—
—
58
0.94
0.26
0.88
—
—
—
—
—
0.0010
59
0.95
0.22
0.71
0.25
—
—
—
—
—
60
0.97
0.49
0.78
—
—
—
—
—
—
61
0.98
0.19
0.51
0.23
—
—
—
—
—
62
1.05
0.30
0.71
—
—
—
0.05
—
—
63
1.19
0.10
0.41
—
—
0.09
—
—
—
Comparative
64
0.77
0.51
1.36
—
—
—
—
—
—
rail steel
65
0.78
0.54
1.30
—
—
—
—
—
—
66
0.82
0.25
1.05
0.25
—
—
—
—
—
67
0.81
0.28
1.08
0.21
—
—
—
—
—
68
0.82
0.49
1.10
0.22
—
—
—
—
—
69
0.82
0.51
1.12
0.24
—
—
—
—
—
TABLE 8
accelerated
maximum wear
existence of the
cooling rate
hardness of
hardness of
amount of
occurrence of the
of gage
gage corner
head to
gage corner
surface damage at
corner portion
portion
portion
portion
the head top portion
rail
No.
(° C./sec)
(HV)
(HV)
(mm)
(1,000,000 times)
Present
54
3
385
288
1.8
no damage occurrence
rail steel
55
10
392
275
1.9
″
56
3
402
306
1.7
″
57
1
411
300
1.6
″
58
5
384
285
1.3
″
59
3
398
294
1.2
″
60
2
380
271
1.2
″
61
3
384
292
1.2
″
62
3
416
304
0.8
″
63
2
421
315
0.6
″
Comparative
64
4*
392
388
3.7
damage occurred
rail steel
65
4
388
305
3.8
no damage occurrence
66
3*
396
390
3.4
damage occurred
67
3
391
319
3.5
no damage occurrence
68
3*
405
399
3.1
damage occurred
69
3
400
315
3.2
no damage occurrence
*Accelerated cooling was applied to the head top portion at the same cooling rate as the gage corner portion.
Further, Table 8 also represents the maximum wear amount of the gage corner portion of the rail testpiece by a water lubrication rolling fatigue tester using disc testpieces 6 and 7 reduced to ¼ the exact size of the rail and the wheel shape shown in FIG. 10 and the existence of the occurrence of the surface damage at the head top portion.
By the way, the construction of the rails is as follows.
Present rails (10 rails) Nos. 54 to 63
Heat-treated rails having a hardness of not less than Hv 360 at the gage corner portion and a hardness of Hv 250 to 320 at the head top portion, having the components within the range described above, and applied with accelerated cooling at the gage corner portion thereof.
Comparative rails (6 rails) Nos. 64 to 69
Comparative rails by eutectoid carbon-containing steel.
The condition of the rolling fatigue test is as follows.
This Example relates to the improvement of the weld joint portion. Table 9 tabulates the principal chemical components of the present rail steel of this Example and a Comparative rail steel.
TABLE 9
principal chemical
composition (wt %)
Si + Cr + Mn
C
Si
Mn
Cr
(wt %)
present
0.90
0.88
0.60
0.58
2.06
rail steel
Comparative
0.91
0.46
0.58
0.21
1.25
rail steel
Incidentally, the construction of each rail is as follows.
Present rail steel
Heat-treated rail having the components listed above, and a pearlite lamella space of not greater than 100 nm. Accelerated cooling was applied to the head portion having a ratio of the cementite thickness to the ferrite thickness of at least 0.15 in the pearlite structure.
Comparative rail steel
A Comparative steel by an eutectoid carbon-containing steel.
The flash butt welding condition is as follows.
Welding machine: Model K-355
Capacity: 150 KVA
Secondary current: 20,000 amp, maximum
Clamp force: 125 t, maximum
Upset amount: 10 mm
The rail steels according to the present invention increase the carbon content to a higher content than the conventional rail steels, narrow the lamella space in the pearlite structure, further restrict the cementite thickness to the ferrite thickness so as to improve breakage resistance due to machining of the pearlite, and obtain the high wear resistance and the high damage resistance by reducing the hardness of the weld portion. Further, the present invention makes it possible to shorten the heat-treatment process and to improve producibility.
Kutaragi, Ken, Ueda, Masaharu, Uchino, Kouichi, Kageyama, Hideaki, Babazono, Koji
| Patent | Priority | Assignee | Title |
| 8210019, | Jul 24 2006 | Nippon Steel Corporation | Method for producing pearlitic rail excellent in wear resistance and ductility |
| 8241442, | Dec 14 2009 | ARCELORMITTAL INVESTIGACION Y DESARROLLO, S L | Method of making a hypereutectoid, head-hardened steel rail |
| 8721807, | Dec 14 2009 | ArcelorMittal Investigacion y Desarrollo, S.L. | Hypereutectoid, head-hardened steel rail |
| 9512501, | Dec 14 2009 | ArcelorMittal Investigacion y Desarrollo, S.L. | Hypereutectoid-head steel rail |
| Patent | Priority | Assignee | Title |
| 4082577, | Aug 16 1974 | Fried. Krupp Huttenwerke AG | Process for the heat treatment of steel |
| 4375995, | May 12 1978 | Nippon Steel Corporation | Method for manufacturing high strength rail of excellent weldability |
| 4486243, | Oct 11 1982 | CENTRE DE RECHERCHES METALLURGIQUES-CENTRUM VOOR RESEARCH IN DE METALLURGIE; METALLURGIQUE & MINIERE DE RODANGE-ATHUS, SA | Method of manufacturing rails |
| 4759806, | Jan 10 1986 | N.V. Bekaert S.A. | Process for manufacturing pearlitic steel wire and product made thereby |
| 4886558, | May 28 1987 | NKK CORPORATION, A CORP OF JAPAN | Method for heat-treating steel rail head |
| 5170932, | Jul 20 1990 | VAE Aktiengesellschaft | Method for connection of railway point components consisting of cast hard manganese steel or manganese steel rails to a rail made from carbon steel |
| 5209792, | Jul 30 1990 | NKK Corporation; Burlington Northern Railroad Company | High-strength, damage-resistant rail |
| 5658400, | Dec 20 1993 | Nippon Steel Corporation | Rails of pearlitic steel with high wear resistance and toughness and their manufacturing methods |
| 5762723, | Nov 15 1994 | Nippon Steel Corporation | Pearlitic steel rail having excellent wear resistance and method of producing the same |
| DE2148722, | |||
| DE2919156, | |||
| EP186373, | |||
| EP469560, | |||
| GB1370144, | |||
| GB1457061, | |||
| JP47007606, | |||
| JP5169292, | |||
| JP5295436, | |||
| JP5295448, | |||
| JP5425490, | |||
| JP55125231, | |||
| JP57198216, | |||
| JP5919173, | |||
| JP6017135, | |||
| JP617193, | |||
| JP62056524, | |||
| JP62127453, | |||
| JP6279925, | |||
| JP6279928, | |||
| JP6280916, | |||
| JP63062846, | |||
| JP7046753, | |||
| JP7046754, | |||
| JP7270336, | |||
| JP8109439, | |||
| JP8109440, | |||
| WO9402652, | |||
| WO9517532, |
| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| Nov 13 1995 | Nippn Steel Corporation | (assignment on the face of the patent) | / |
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