US2639985A - Bearing and steel therefor - Google Patents

Description

Patented May 26, 1953 BEARING AND STEEL THEREFOR Kan F. "Scha'uwe'cker, Franklin Park, 111., assign-or to United States Steel Corporation, a camera.-

tion of NewJersey No Drawing. Continuation of application Serial N0. 109,803, August. 11, 194,9. 31111502121611 A'I lnfil 30, 1951, Serial'No. 223,830

2 Glaims.

This invention relates to improvements in; bearings and steels therefor. The service'life of bearings, such as ball and roller bearings, is in many installations .toa large degree dependent on the resistance thereof to softening under the high temperatures to which they are subjected. Moreover in forming bearings, it is necessary that" the steel have a high degree of forg'eabili'ty.

It is accordingly an object of the present invention to provide steel'bearings which have an increased service life despite their being subjected to high temperatures.

It is a further object to provide steels for bearings which are relatively stable at high temperatures and which have a high degree'of resistance to softening at elevated temperatures.

' t is another object to provide steels for bearings-which will regain to a large degree any hardnessloss due to being subjected to unduly high temperatures in service.

It is a iurtheraobject toprovide such qualities in a steel-which is highly forgeable.

I have, discovered that the foregoing objects can be attained by alloying between .75 and 1.25% aluminum and. .20 and 55%. silicon, with the aluminum plus silicon content being between'.-1.00 and 1.75%, with hardenable bearing steel. While this is beneficial to hypereutectoid'bearing steels generally, it is particularly trueof hypereutectoid bearing steels having a room temperature Rockwell C hardness or at least '60 after quenching. Preferably the bearing steels of this invention will contain between .39 5 and 1.15% carbon, .25 to 6G% manganese, .20 to 50% silicon, ..35% maximum nickel, 1.35 to 1.65% chromium, .35 maximum copper with the balanceiron except for residual elements incommonamounts.

{The hereinafter presented data obtained. from the heats of steels shown in Table I produced Icy-conventional practice in a high-frequency in duction furnace are believed't'o clearly-illustrate ability of my improved steel to harden and retain its hardness despite :being subjected to high temperatures. 1

TABLE I Heat No. Mn Si Ni or Mo- A1 1 1.02 .59 .50 1.50 None 2. 1. 09 .62 .59 1. 58 1.18 3 1.02 .35 .29 21 1. 51 .24 None 1 1.10 .41 .30 1. 44 1.12 5 64 96 20 24 None fi 63 .99 .41 .25 1. 05 7 .51 .75 .21 1. 75 .99 .25 None 10 8 .52 .80 .23 1. 65 .80 .26 1.06

;-The hardness of certain of the foregoing steels was determined after heating for 20 minutes at the temperatures :set forth in Table II. The specimens used were about 1 inch in cross section and the hardness measured with a diamond penetrator. For the sake of convenience of comparison, the values obtained were converted to Rockwell C readings, using conversion figures recommended by the-American society for Tes'tmg- Materials 132-48437).

TA LE Testing to- 3N0 Al 4-AI 7N0 Al Room (before test) 200 J5 0 F Room (after test) An examination 'of this table shows that the decrease or hardness of specimens heated to elevated temperatures is much slower for the steel containing 1% :aluminum and theqrec'overy after return to room temperature much greater.- it. is also noted that these qualities are much more pronounced in the hypereutectoid steel containing aluminum and low -nickel.

The resistance to softening of the steels of my invention upon holding at elevated temperatures for prolonged periods of time is illustrated in the following Table III. This table gives the room temperature hardness values in Rockwell C figures obtained after heating, for the temperatures and times indicated, specimens quenched in water from above the An point and.

TABLE III 1--No A1 2-A1 5-No Al 5Al 8-Al As quenched 65. 66. 0 64. 02. 0 64. 0 Drawn at 350 F. for:

2 Hours i 60. 3 62. 2 58. 0 57. 5 55. 0 4 Hours 60. 6 62. 8 56. 0 55. 0 54. 5 28 Hours 60. 8 62. 8 58.0 58.0 52.0 Drawn at 450 F. for:

60. 4 62. 3 54. 0 58. O 55. 0 60. 6 62. 8 52. 0 58. O 56. 0 28 Hours 58. 2 62. 8 55. 5 55. 0 53. 0 Drawn at 550 F. for:

2 Hours 59. 4 62. 1 55.0 56.0 53.0 4 Hours 59. 4 62. 2 54. 0 57. 0 54. 0 28 Hours 59. 2 62. 1 52. 0 56. 6 51. 0

The figures of the foregoing Table III show the influence of 1% aluminum in resistance to softening after various periods at various temperatures. The difference is again much more pronounced in the hypereutectoid steels.

It is clear from the tables thatalloying hardenable steels with about 1% of aluminum ranof heating. This permits operation of bearing made therefrom at high temperatures, and greatly reduces the dangerscaused by soften-.

, Moreover, after drawing at 550 F. for 28 hours,

.20. ders them more resistant tothesoftening effect .cient1y hard as quenched.

the steel containing less than 1% aluminum plus silicon did not-retain hardness for satisfactory service at such temperature, falling below 60 R The steel with over 1.75% aluminum plus silicon retained its hardness, but was not suffi- It should be noted ing of steel induced by temporary overheating. that the 1 2% aluminum plus silicon not only In the case of heat No. 4, for example, no damdeveloped satisfactory hardness but also retained age for bearings composed of such steel can be its hardness satisfactorily for bearing service. expected after overheating for 20 minutes at The following Table VI indicates the results 600 F., while the same overheating would seriof upset forging tests made on specimens /2" ously-affect bearings of the same composition 30 diameter x 1" specimens of the above strips without aluminum. which were reduced to /8" and A" thickness.

' TABLE VI Forgeability Upset I Forging Tempe ature, F. Heat No. gfi fig f fi die. x 1" 1,850 1,950 2,050 2,150

9 )4; surface 0 I Surface Surface 0. Surface 0. K.

do. 110.... .do Do. 10 H 34 .do ...do. Do. .do.. do D0. 11 Unforgeable. Ruptured... upt Surface Rough.

Ruptured. Surface 0. Surface Rough. Ruptured.

, Such beneficial qualities, however, are only This clearly shows that a total aluminum plus obtainable when the aluminum plus the silicon silicon of over 1.75% results in the steel not content is maintained in the range of 1.00 to nly having p00 h de abi ty but also are not 1.75%. To further illustrate this, the following satisfactory for hot working by commercial mill heats of steel were made and tested as follows: p a ce This is a continuation of my copending ap- TABLE plication Serial No. 109,803, filed August 11, 1949, j; now abandoned. HGBFNQ C or A1 While I have shown and described several I I specific embodiments of my invention, it will be 9 'fgg fgg fiy "?3; "f2 understood that these embodiments are merely 10 1.18 for the purpose of illustration and description and that various other forms may be devised Specimens of these heats of 1%." diameter rgg igggg zg fi g m mventlon' as defined turned to 1" diameter by 3" in length were I claim hed f om normalized 1600 F and water quenc r l. A bearing steel characterized by good forgeabout 1475 The room temperature Rock' ability and by high hardenability and retention wen C hardnesos m q g of hardness after quenching from above its A61 drawing at 550 for 8 ours gwen m 8 point and thereafter subjected to prolonged following Table 65 heating at 550 R, said steel containing from TABLE v about .95 to 1.15% carbon, .25 to .60% manganese, 35% maximum nickel, 1.35 to 1.65% Drawn 550 F, chromium, .35% maximum copper .75 to 1.25% h I I Dfl AsQuenc ed M2811 l Hence aluminum and .20 to 50% silicon, the total of aluminum plus silicon being between about 1.00 2 2, g g-g and 1.75%, the balance being iron and residual iiIIIIIIIIIIIIIIII H.614 11.5814 310 amounts of other elements.

2. A bearing steel characterized by good forgeability and by a hardness in excess of 60 Re after water quenching from about 1475" F. re-

tention of room temperature hardness in excess of 60 Re after prolonged heating at 550 F., said steel containing from about .95 to 1.15% car bon, .25 to .60% manganese, 35% maximum nickel, 1.35 to 1.65% chromium, 35% maximum copper, .75 to 1.25% aluminum and .20 to 50% silicon, the total of aluminum plus silicon being between about 1.00 and 1.75, the balance iron and residual amounts of other elements.

KARL F. SCI-IAUWECKER.

References Cited in the file of this patent Number FOREIGN PATENTS

Claims (1)

1. A BEARING STEEL CHARACTERIZED BY GOOD FORGEABILITY AND BY HUGH HARDENABILITY AND RETENTION OF HARDNESS AFTER QUENCHING FROM ABOVE ITS A-E1 POIINT AND THEREAFTER SUBJECTED TO PROLONGED HEATING AT 550. F., SAID STEEL CONTAINING FROM ABOUT .95 TO 1.15% CARBON, .25 TO .60% MANGANESE, .35% MAXIMUM NICKEL, 1.35 TO 1.65% CHROMIUM, .35% MAXIMUM COPPPER, .75 TO 1.25% AALUUMINUM PLUS SILICON, THE TOTAL OF ALUMINUUM PLUS SILICON BEING BETWEEN ABOUT 1.00 AND 1.75%, THE BALANCE BEING IRON AND RESIDUAL. AMOUNTS OF OTHER ELEMENTS.