US3205556A - Method for increasing endurance limit of steel articles - Google Patents
Method for increasing endurance limit of steel articles Download PDFInfo
- Publication number
- US3205556A US3205556A US222628A US22262862A US3205556A US 3205556 A US3205556 A US 3205556A US 222628 A US222628 A US 222628A US 22262862 A US22262862 A US 22262862A US 3205556 A US3205556 A US 3205556A
- Authority
- US
- United States
- Prior art keywords
- peening
- shot
- steel
- temperature
- article
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000000034 method Methods 0.000 title claims description 14
- 229910000831 Steel Inorganic materials 0.000 title description 18
- 239000010959 steel Substances 0.000 title description 18
- 230000001965 increasing effect Effects 0.000 title description 4
- 238000005480 shot peening Methods 0.000 claims description 14
- 238000012360 testing method Methods 0.000 description 9
- 238000005422 blasting Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000003534 oscillatory effect Effects 0.000 description 2
- 230000002441 reversible effect Effects 0.000 description 2
- 238000005496 tempering Methods 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- 229910001208 Crucible steel Inorganic materials 0.000 description 1
- 229910000760 Hardened steel Inorganic materials 0.000 description 1
- 229910000639 Spring steel Inorganic materials 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000003028 elevating effect Effects 0.000 description 1
- 238000009661 fatigue test Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000011236 particulate material Substances 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- WQGWDDDVZFFDIG-UHFFFAOYSA-N pyrogallol Chemical compound OC1=CC=CC(O)=C1O WQGWDDDVZFFDIG-UHFFFAOYSA-N 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
- C21D7/04—Modifying the physical properties of iron or steel by deformation by cold working of the surface
- C21D7/06—Modifying the physical properties of iron or steel by deformation by cold working of the surface by shot-peening or the like
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/47—Burnishing
Definitions
- this invention depends upon the working of the surface of a steel article by impinging against the surface thereof hard particulate materials, such as steel shot. It has been known that shot-peening of steel springs, for example, effects a cold working of the surface, and so alters the crystalline structure of the skin portion as to beneficially increase the endurance limit or fatigue characteristics against failures resulting from surface defects, such as notches or scores which may result from prior operation. Such scores, notches, grooves and the like provide points of incipient premature fatigue or fracture.
- the present invention is in a method of improving the endurance characteristics of steel articles which comprises adjusting the temperature of such article to Within the range from about 200 F. to about 600 F. and shot-peening the article at such elevated temperature in the unstressed condition.
- Shot-peening is an operation whereby hardened steel shot, preferably averaging about one thirty-second of an inch in diameter, are caused to impinge upon the surface of the steel article being treated.
- the shot are thrown from the periphery of a wheel which is running at high speed, or they may be directed by a high velocity air stream against the surface of the article. In either case, the shot are caused to travel at such a high velocity that, when they impinge upon the surface of the article, they will remove any scale that is present and also effect a working of the surface.
- Lineal velocities in commercial use range from about to about 350 feet per second.
- the surface Upon completion of the shot blasting operation, the surface will have a very fine-grained frosty or pebbly appearance. From 2 to 10 pounds of shot are impinged per square inch of surface being treated in a period of time ranging from 10 to 60 seconds.
- test springs were fiat and fashioned from the same bundle of steel, and processed at the same time to a Brinell hardness within the range above stated. The tests were performed on a Pangborn Machine No. 4418.
- the surface temperature of each was measured with a Pyro surface pyrometer.
- the desired temperature shown in the data of Table I was attained by spontaneous cooling, the spring element was fed into the peening machine.
- the temperature .at which peening is done may be attained by cooling from a tempering temperature which is well in excess of the peening temperature range, or by elevating the temperature of a pre-tempered article to within the desired range.
- test plates were preset by placing each plate at the bottom of the stroke (maximum stress) before setting up with a Huggenberger tensometer for an initial stress range of 30,000 to 160,000 p.s.i. Each piece was cycled to failure by fracture.
- the method of improving the endurance and set characteristics of steel articles which comprises in combination the steps of adjusting the temperature of the article to within the range of from about 200 F. to about 600 F. and shot-peening the article in the unstressed condition at such temperature.
- the method of improving the endurance and set characteristics of leaf type steel spring elements which comprises in combination the steps of adjusting the temperature of the spring element to within the range of from about 200 F. to about 600 F. and shot peening the article in the unstressed condition at such temperature.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Springs (AREA)
- Heat Treatment Of Articles (AREA)
- Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
Description
United States Patent 3,205,556 METHOD FOR INCREASING ENDURANCE LIMlT OF STEEL ARTICLES John F. Romans, Berea, Ohio, assignor to Eaton Manufgfituring Company, Cleveland, Ohio, a corporation of No Drawing. Filed Sept. 10, 1962, Ser. No. 222,628 3 Claims. (Cl. 2990) This invention relates, as indicated, to a method for improving certain characteristics of steel articles, and more particularly to a method for increasing the strength and hardness characteristics of steel surfaces, particularly in spring steel surfaces, with a resultant increase in the endurance limit of the article.
Generally speaking, this invention depends upon the working of the surface of a steel article by impinging against the surface thereof hard particulate materials, such as steel shot. It has been known that shot-peening of steel springs, for example, effects a cold working of the surface, and so alters the crystalline structure of the skin portion as to beneficially increase the endurance limit or fatigue characteristics against failures resulting from surface defects, such as notches or scores which may result from prior operation. Such scores, notches, grooves and the like provide points of incipient premature fatigue or fracture.
Early disclosures of the utilization of shot-peening as a means for improving the characteristics of springs is found in the patent to Vorwerk, 1,946,340, and the patent to Minich, 2,077,629. Both these patentees treated the entire surface by impinging small steel balls against the surface and obtained improved characteristics, i.e. hardness and resistance to fatigue failure.
From time to time, the prior art has made improvements upon the basic concept of shot-peening. For example, it has been found that improved results are obtained when instead of indiscriminate blasting of both of the tension and compression sides of spring leaves, for instance, only the tension side should be so treated (Patent No. 2,252,823).
More recently, it has been found that the endurance characteristics of single leaf springs can be improved by shot-peening the tension surface while the spring is reverse stressed near to its yield point (Patent No. 2,608,752). When peening is done under these conditions, the spring takes a considerable set during peening which must be allowed for when designing the quench form.
It has now been found that the amount of set can be greatly reduced by carrying out the surface working operation at an elevated temperature, i.e. in the range of from about 200 F. to 600 F. without imposing the article to stress conditions, and consequently minimizing the extent of set imposed on the article. So far as I am aware, shot peening unstressed articles at such elevated temperatures is novel per se.
Moreover, certain articles are not easily adaptable to being shot-peened under stressed conditions, e.g. bearing mounts. Nevertheless, they also require substantial improvement in fatigue characteristics for effective service and are capable of being beneficiated in accordance with the present invention. This invention is especially adapted for use in the manufacture of passenger car rear suspension springs of the single or multiple leaf types and having a predetermined contour or profile. It is also well adapted for the manufacture of fiat springs having a rectilinear profile or contour. A principal advantage of this process is that contoured articles such as these do not undergo substantial change in contour or profile when shot-peened in accordance herewith.
Briefly stated, then, the present invention is in a method of improving the endurance characteristics of steel articles which comprises adjusting the temperature of such article to Within the range from about 200 F. to about 600 F. and shot-peening the article at such elevated temperature in the unstressed condition.
Shot-peening is an operation whereby hardened steel shot, preferably averaging about one thirty-second of an inch in diameter, are caused to impinge upon the surface of the steel article being treated. In one device, the shot are thrown from the periphery of a wheel which is running at high speed, or they may be directed by a high velocity air stream against the surface of the article. In either case, the shot are caused to travel at such a high velocity that, when they impinge upon the surface of the article, they will remove any scale that is present and also effect a working of the surface. Lineal velocities in commercial use range from about to about 350 feet per second. Upon completion of the shot blasting operation, the surface will have a very fine-grained frosty or pebbly appearance. From 2 to 10 pounds of shot are impinged per square inch of surface being treated in a period of time ranging from 10 to 60 seconds.
In order to illustrate the process of the present invention, a series of test pieces of steel, SAE 5160 2.5" by 0.246 leaf type spring, 16" long having a Brinell hardness number of 430-444 were peened at room temperature and at elevated temperatures with cast steel shot having the characteristics hereinafter set forth.
All test springs were fiat and fashioned from the same bundle of steel, and processed at the same time to a Brinell hardness within the range above stated. The tests were performed on a Pangborn Machine No. 4418.
As the fiat spring elements undergoing test left the tempering furnace, the surface temperature of each was measured with a Pyro surface pyrometer. When the desired temperature shown in the data of Table I was attained by spontaneous cooling, the spring element was fed into the peening machine. In actual practice, the temperature .at which peening is done may be attained by cooling from a tempering temperature which is well in excess of the peening temperature range, or by elevating the temperature of a pre-tempered article to within the desired range.
In the fatigue testing machine after the peening operation, the central ten inches of the test elements were placed under constant stress. The test plates were preset by placing each plate at the bottom of the stroke (maximum stress) before setting up with a Huggenberger tensometer for an initial stress range of 30,000 to 160,000 p.s.i. Each piece was cycled to failure by fracture.
These tests show that peening under elevated temperatures without reverse stress causes substantially less change in a 16" chord height for the spring as a result of peening, than is found when peening is done at ordinary temperatures but under stress.
The following table summarizes data obtained, the numerical values being the average of two test plates at each temperature value.
TABLE I Change in 16" Chord Height Due to Peening, inches Average Fatigue Lite Room Temperature 300 F.
It is anticipated that the effective temperature range will vary with the composition of the steel being treated.
In all cases, the fatigue life of the steel spring element peened at room and elevated temperatures was increased by a factor of from five to twenty times that of an unpeened spring element of the same material. It will also be observed that the amount of variation in the chord height of a 16" long specimen in the case of the stresspeened material was about three times as great as the variation in the chord height due to temperature peening. Chord heights are measured at the mid-point of the elongated specimen supported by its extremities on a plane surface.
The shot analysis of the shot used in these tests is as set forth in Table II.
Thus, there has been provided an improved process for shot peening steel articles, particularly articles subject to oscillatory motion and failure by fatigue, e.g. springs of the leaf type, bearing mountings, etc., which process depends upon the utilization of elevated temperatures in the range of from about 200 F. to about 600 F. and shot peening the articles at such temperature under normal shot peening procedures in the stress-free or unstressed condition.
Other modes of applying the principle of this inven tion may be employed instead of those specifically set forth above, changes being made as regards the details herein disclosed provided the elements set forth in any of the following claims, or the equivalent of such be employed.
It is, therefore, particularly pointed out and distinctly claimed as the invention:
1. The method of improving the endurance and set characteristics of steel articles which comprises in combination the steps of adjusting the temperature of the article to within the range of from about 200 F. to about 600 F. and shot-peening the article in the unstressed condition at such temperature.
2. The method of improving the endurance and set characteristics of leaf type steel spring elements which comprises in combination the steps of adjusting the temperature of the spring element to within the range of from about 200 F. to about 600 F. and shot peening the article in the unstressed condition at such temperature.
3. The method of improving the endurance and set characteristics, of contoured steel articles adapted to be subjected to oscillatory stresses without substantially changing said contour which comprises in combination the step of adjusting the temperature of the article to within the range of from about 200 F. to about 600 F.,
and shot peening the article in the unstressed condition at such temperature. 7
References Cited by the Examiner .Corp., 1946, Mishawaka, Indiana, pages 1 and 78.
RICHARD H. EANES, 111., Primary Examiner.
Claims (1)
1. THE METHOD OF IMPROVING THE ENDURANCE AND SET CHARACTERISTICS OF STEEL ARTICLES WHICH COMPRISES IN COMBINATION THE STEPS OF ADJUSTING THE TEMPERATURE OF THE ARTICLE TO WITHIN THE RANGE OF FROM ABOUT 200* F. TO ABOUT 600* F. AND SHOT-PEENING THE ARTICLE IN THE UNSTRESSED CONDITION AT SUCH TEMPERATURE.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US222628A US3205556A (en) | 1962-09-10 | 1962-09-10 | Method for increasing endurance limit of steel articles |
| GB34845/63A GB991844A (en) | 1962-09-10 | 1963-09-03 | Method for increasing endurance limit of steel articles |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US222628A US3205556A (en) | 1962-09-10 | 1962-09-10 | Method for increasing endurance limit of steel articles |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3205556A true US3205556A (en) | 1965-09-14 |
Family
ID=22833025
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US222628A Expired - Lifetime US3205556A (en) | 1962-09-10 | 1962-09-10 | Method for increasing endurance limit of steel articles |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US3205556A (en) |
| GB (1) | GB991844A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4776251A (en) * | 1987-06-12 | 1988-10-11 | Pacific Saw And Knife Company | Circular saw blade with circumferentally extending laser-cut slots |
| EP0431224B1 (en) * | 1989-12-05 | 1996-02-21 | Horikiri Spring Mfg. Co. Ltd. | Method of manufacturing a leaf of a leaf spring |
| US5697265A (en) * | 1995-01-23 | 1997-12-16 | Mccomber; Larry J. | Trowel having imposed blade stresses and method of manufacture |
| US6032320A (en) * | 1995-01-23 | 2000-03-07 | Marshalltown Trowel Company | Trowel having imposed blade stresses and method of manufacture |
| US20080257458A1 (en) * | 2004-12-21 | 2008-10-23 | Ab Skf | Method for Case Hardening a Component by Means of Oil Jets and Device for Carrying Out Said Method |
| US20090126435A1 (en) * | 2006-05-06 | 2009-05-21 | Erwin Bayer | Method for the surface peening of a component |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2252823A (en) * | 1940-09-28 | 1941-08-19 | Eaton Mfg Co | Apparatus for shot blasting leaf springs |
-
1962
- 1962-09-10 US US222628A patent/US3205556A/en not_active Expired - Lifetime
-
1963
- 1963-09-03 GB GB34845/63A patent/GB991844A/en not_active Expired
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2252823A (en) * | 1940-09-28 | 1941-08-19 | Eaton Mfg Co | Apparatus for shot blasting leaf springs |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4776251A (en) * | 1987-06-12 | 1988-10-11 | Pacific Saw And Knife Company | Circular saw blade with circumferentally extending laser-cut slots |
| EP0431224B1 (en) * | 1989-12-05 | 1996-02-21 | Horikiri Spring Mfg. Co. Ltd. | Method of manufacturing a leaf of a leaf spring |
| US5697265A (en) * | 1995-01-23 | 1997-12-16 | Mccomber; Larry J. | Trowel having imposed blade stresses and method of manufacture |
| US5791009A (en) * | 1995-01-23 | 1998-08-11 | Marshalltown Trowel Company | Trowel having imposed blade stresses and method of manufacture |
| US6032320A (en) * | 1995-01-23 | 2000-03-07 | Marshalltown Trowel Company | Trowel having imposed blade stresses and method of manufacture |
| US20080257458A1 (en) * | 2004-12-21 | 2008-10-23 | Ab Skf | Method for Case Hardening a Component by Means of Oil Jets and Device for Carrying Out Said Method |
| US9028627B2 (en) * | 2004-12-21 | 2015-05-12 | Ab Skf | Method for case hardening a component by means of oil jets and device for carrying out said method |
| US20090126435A1 (en) * | 2006-05-06 | 2009-05-21 | Erwin Bayer | Method for the surface peening of a component |
Also Published As
| Publication number | Publication date |
|---|---|
| GB991844A (en) | 1965-05-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3073022A (en) | Shot-peening treatments | |
| Mattson et al. | Effect of shot-peening variables and residual stresses on the fatigue life of leaf-spring specimens | |
| Farrahi et al. | Effect of shot peening on residual stress and fatigue life of a spring steel | |
| US3238072A (en) | Method of making taper leaf springs | |
| US3705511A (en) | Low penetration ball forming process | |
| EP1201773B1 (en) | High-strength spring and production method therefor | |
| JP4183129B2 (en) | Leaf spring for vehicle and manufacturing method thereof | |
| US6346157B1 (en) | Manufacturing method of suspension spring for car | |
| US3205556A (en) | Method for increasing endurance limit of steel articles | |
| US3516874A (en) | Method of increasing the fatigue life of metal parts | |
| US2717846A (en) | Method of surface hardening ferrous metals | |
| US4239804A (en) | Method for treating metal articles for rust corrosion protection and article produced thereby | |
| US3339908A (en) | Tapered leaf springs | |
| Herbert et al. | ABRASION | |
| US2958925A (en) | Shot peen inspection technique | |
| JP2001079766A (en) | Projection material for shot peening | |
| Bird et al. | The effect of peening-shot size on the performance of carbon-steel springs | |
| US3764401A (en) | Metallic articles and the manufacture thereof | |
| JPH0123524B2 (en) | ||
| USRE26714E (en) | Method of making taper leap springs | |
| GB651230A (en) | Improved manufacture of spring leaves | |
| O'Hara | Developments in the shot peening process | |
| DeLitizia et al. | Shot peening for improved castings | |
| Meguid et al. | Some factors in the shot-peening and peen-forming processes | |
| Sadallah et al. | The effect of high temperature shot peening on the surface integrity of 2024-T351 aluminum alloy. |