CA1178517A - Ferrous materials - Google Patents
Ferrous materialsInfo
- Publication number
- CA1178517A CA1178517A CA000373498A CA373498A CA1178517A CA 1178517 A CA1178517 A CA 1178517A CA 000373498 A CA000373498 A CA 000373498A CA 373498 A CA373498 A CA 373498A CA 1178517 A CA1178517 A CA 1178517A
- Authority
- CA
- Canada
- Prior art keywords
- plastic deformation
- grain structure
- hardness
- materials
- ferrous materials
- 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
Links
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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/30—Stress-relieving
-
- 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- Physics & Mathematics (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Health & Medical Sciences (AREA)
- Child & Adolescent Psychology (AREA)
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
Abstract:
The ferrous materials of this invention, which are produced in the shape of tubes or bars by subjecting to plastic deformation by drawing and subsequently by sub-jecting to annealing treatment conducted under stated conditions, retain a flattened structure substantially free from recrystallization and acquire a hardness which is greater by 55% to 125% than the hardness acquired by iron and steel materials which are treated by full anneal-ing. The ferrous materials notably excel the conventional products in terms of fatigue strength against bending, vibrations, etc.
The ferrous materials of this invention, which are produced in the shape of tubes or bars by subjecting to plastic deformation by drawing and subsequently by sub-jecting to annealing treatment conducted under stated conditions, retain a flattened structure substantially free from recrystallization and acquire a hardness which is greater by 55% to 125% than the hardness acquired by iron and steel materials which are treated by full anneal-ing. The ferrous materials notably excel the conventional products in terms of fatigue strength against bending, vibrations, etc.
Description
:1 ~.'78Sl~
IMPROVEMENTS IN AND REL~TING TO FERROUS MATERIALS
This invention relates to ferrous materials and in particular, tubes or bars of iron or steel which after plastic deformation have been subjected to low-temperature annealing in order to remove the residual stress generated during the plastic deforming step.
Conventional tubes or bars of iron and steel such as, those specified by the SAE Standard, "Fuel Injection Tubing - SAE
J529b," which are annealed after plastic deformation by e.g.
drawings assume a normal structure containing a re-crystallized inner structure and acquire a hardness approximating to the hardness of the raw material prior to plastic deformation.
This is because it has been the practice to effect complete or full annealing. ~s a result, conventional materials of this kind have tended to suffer from degradation of fatigue strength as shown in Table 1 and by the curve (B) in the graph of Figure 1 comparing the fatigue properties. Also products fabricated from these materials tend to exhibit the early occurrence of cracks and fractures in fastened portions, joined ends, etc , owing to the impacts such as of bending and vibrations.
One object of this invention is to at least mitigate the above disadvantages.
.,~ .
11178Sl'7 According to this invention we propose a method of treating ferrous materials comprising subjecting the material to plastic deformation whereby a ~lattened grain structure is produced, and subsequently annealing the material in such a way as to retain the flattened grain structure. The invention also includes ferrous material which has been treated by the method according to the invention. Other features of the invention are set forth in the appendant claims.
Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings.
Figure 1 is a graph comparing the fatigue properties of products fabricated from iron or steel materials according to the present invention with those of products fabricated from conventional iron or steel materials.
Figure 2 i5 a photomicrograph showing the grain structure material according to the present invention (magni~ication -XlOO).
Figure 3 is a photomicrograph showing the grain structure of conventional material ~magnification - XlOO).
The`iron and steel materials according to this invention, which preferably have a carbon content in the range O.O5/O to 0.45~
(by weight) retain a flattened grain structure substantially free from recrystallization and acquire a hardness which is greater by- 55/o to 125% than the hardness acquired by iron and steel materials which are treated by full annealing and a notably enhanced fatigue strength as indicated by the curve (A) 351'-7 in the graph o~ Figure 1. This is achieved by fi~ing the reduction in area,(i.e. the reduction ratio) during low--temperature plastic deformation within the range 20% to 60~ -so that the material retains à uniform ~lattened grain structure and subsequent annealing by a low-temperature working at a temperature and for a period of time commensurate with the aforementioned ratio of treatment, namely~ the highest temperature and the longest duration beyond which the recrystal-lization occur~.
The reason for specifying a hardness in the range mentioned above naturally concerns the outcome of the plastic deformation.
When the increase of hardness fails to reach the lower limit Of 55~ over the level acquired by full annealing, the materials under treatment do not retain a uniformly w~rked, uniform flattened grain structure and, as the result, do not exhibit a notable enhancement of fatigue strength. When the increase in hardness exceeds 125~ (i.e. is not increased in proportion to the ratio during plastic deformation) the grain boundary slippage in the flattened grain structure gains in intensity to such an extent that the grain boundary is degraded so eventually lowering the fatigue limit.
Example:
A carbon steel pipe of machine structure grade (STKM-13A, killed steel) measuring 12.7 mm in outside diameter and 2.5 mm in wall thickness was used as a raw steel material. By subjecting this raw steel materi~l to plastic deformation b~;
drawing with the reduction ratio fi~ed at 480h, there was obtained a tube measuring 8 . 0 mm in outside diameter and 2.3 mm in wall thickness and Hv 202 in hardness. Subsequently, it was subjected-to a low-temperature annealing treatment in a pusher type heating furnace under a non-o~idising atmosphere at 410C for 35 minutes. The final product exhibited a tensile strength o~ 67.6 kg/mm2, an elongation of 12~ and a hardness of Hv 190. This product retained a flattened grain structure free from recrystallization as shown in the photo-micrograph of Figure 2 and possessed fatigue properties shown in Table 1 and by the graph (A) in the graph of Figure 1.
The conventional product as indicated in Table 1 and by the curve (B) in the graph of Figure 1, was a tube e~hibiting a tensile strength of 39.3 kg/mm , an elongation of 42% and a hardness of Hv117 which was obtained by subjecting the tube measuring` 8.0 mm in outside diameter, 2.3 mm in wall thickness and Hv202 in hardness and obtained by the same plastic deformation by drawing as mentioned above to a complete annealing treatment in a pusher type heating furnace under a 20 non-oxidising atmosphere at 730C for 10 minutes. This product possessed a recrystallized structure as shown by the photo-micrograph of Figure 3.
Fi~e test pieces taken from each of the products (A) and (~) were subjecled to a repeated bending test for ~atigue strength.
The results were as shown below.
:~ ~'7~5 o Method of measurement - A test piece was held horizontally with one end fastened by a stationary holder and the remaining free end of the test piece was vibrated in a vertical direction.
O = 2 a~ ( 1 ) wherein, ~ stands for the stated stress, Q stands for the distance the fastened point to the working point of force.
d stands for the diameter of the test piece, and E stands for the Youngts modulus (2.1 ~ 104kg/mm2) of the material.
The test piece was given a repeated bending with the amplitude calculated by the formula (1) shown above, with count taken of the bends given to the test piece until a fracture was sustained by the test piece.
o Test results Stated Number of repeated bends given until fracture 20 stress2 Product ~A) o~ Convention produc-t (B) _ Fracture sustained after Fracture sustained after 1.6 x 106 bends. 1.5 x 105 bends.
27 Fracture sustained after Fracture sustended after 3.8 x 106 bends. 2.4 x 105 bends.
24 No fracture sustained Fracture sustained after after 1.0 ~ 107 bends. 4.8 x 105 bends.
21 .~ " Fracture sustended a~ter 1.1 x 10~ bends.
18 .. .. No fracture sustained after _ __ _ 1.0 x 107 bends.
.11'7 As described above, owing to the annealing treatment which is performed in the form of a low-temperature working, the iron and steel materials produced according to the present invention retain a uniform flattened grain structure free from residual stress and incapable of recrystallization, and possess a hardness which is greater by 55% to 125% than that of con-~
ventional materials which have undergone complete annealing, Consequently they enjoy a notable enhancement in the fatigue strength against bending and vibrations. The materials, when used in fabricated products such as tubes and bars, preclude occurrence of cracks and fractures in the fastened portions, joined ends and so forth. The products of this invention, therefore, prove highly useful for industrial applications.
IMPROVEMENTS IN AND REL~TING TO FERROUS MATERIALS
This invention relates to ferrous materials and in particular, tubes or bars of iron or steel which after plastic deformation have been subjected to low-temperature annealing in order to remove the residual stress generated during the plastic deforming step.
Conventional tubes or bars of iron and steel such as, those specified by the SAE Standard, "Fuel Injection Tubing - SAE
J529b," which are annealed after plastic deformation by e.g.
drawings assume a normal structure containing a re-crystallized inner structure and acquire a hardness approximating to the hardness of the raw material prior to plastic deformation.
This is because it has been the practice to effect complete or full annealing. ~s a result, conventional materials of this kind have tended to suffer from degradation of fatigue strength as shown in Table 1 and by the curve (B) in the graph of Figure 1 comparing the fatigue properties. Also products fabricated from these materials tend to exhibit the early occurrence of cracks and fractures in fastened portions, joined ends, etc , owing to the impacts such as of bending and vibrations.
One object of this invention is to at least mitigate the above disadvantages.
.,~ .
11178Sl'7 According to this invention we propose a method of treating ferrous materials comprising subjecting the material to plastic deformation whereby a ~lattened grain structure is produced, and subsequently annealing the material in such a way as to retain the flattened grain structure. The invention also includes ferrous material which has been treated by the method according to the invention. Other features of the invention are set forth in the appendant claims.
Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings.
Figure 1 is a graph comparing the fatigue properties of products fabricated from iron or steel materials according to the present invention with those of products fabricated from conventional iron or steel materials.
Figure 2 i5 a photomicrograph showing the grain structure material according to the present invention (magni~ication -XlOO).
Figure 3 is a photomicrograph showing the grain structure of conventional material ~magnification - XlOO).
The`iron and steel materials according to this invention, which preferably have a carbon content in the range O.O5/O to 0.45~
(by weight) retain a flattened grain structure substantially free from recrystallization and acquire a hardness which is greater by- 55/o to 125% than the hardness acquired by iron and steel materials which are treated by full annealing and a notably enhanced fatigue strength as indicated by the curve (A) 351'-7 in the graph o~ Figure 1. This is achieved by fi~ing the reduction in area,(i.e. the reduction ratio) during low--temperature plastic deformation within the range 20% to 60~ -so that the material retains à uniform ~lattened grain structure and subsequent annealing by a low-temperature working at a temperature and for a period of time commensurate with the aforementioned ratio of treatment, namely~ the highest temperature and the longest duration beyond which the recrystal-lization occur~.
The reason for specifying a hardness in the range mentioned above naturally concerns the outcome of the plastic deformation.
When the increase of hardness fails to reach the lower limit Of 55~ over the level acquired by full annealing, the materials under treatment do not retain a uniformly w~rked, uniform flattened grain structure and, as the result, do not exhibit a notable enhancement of fatigue strength. When the increase in hardness exceeds 125~ (i.e. is not increased in proportion to the ratio during plastic deformation) the grain boundary slippage in the flattened grain structure gains in intensity to such an extent that the grain boundary is degraded so eventually lowering the fatigue limit.
Example:
A carbon steel pipe of machine structure grade (STKM-13A, killed steel) measuring 12.7 mm in outside diameter and 2.5 mm in wall thickness was used as a raw steel material. By subjecting this raw steel materi~l to plastic deformation b~;
drawing with the reduction ratio fi~ed at 480h, there was obtained a tube measuring 8 . 0 mm in outside diameter and 2.3 mm in wall thickness and Hv 202 in hardness. Subsequently, it was subjected-to a low-temperature annealing treatment in a pusher type heating furnace under a non-o~idising atmosphere at 410C for 35 minutes. The final product exhibited a tensile strength o~ 67.6 kg/mm2, an elongation of 12~ and a hardness of Hv 190. This product retained a flattened grain structure free from recrystallization as shown in the photo-micrograph of Figure 2 and possessed fatigue properties shown in Table 1 and by the graph (A) in the graph of Figure 1.
The conventional product as indicated in Table 1 and by the curve (B) in the graph of Figure 1, was a tube e~hibiting a tensile strength of 39.3 kg/mm , an elongation of 42% and a hardness of Hv117 which was obtained by subjecting the tube measuring` 8.0 mm in outside diameter, 2.3 mm in wall thickness and Hv202 in hardness and obtained by the same plastic deformation by drawing as mentioned above to a complete annealing treatment in a pusher type heating furnace under a 20 non-oxidising atmosphere at 730C for 10 minutes. This product possessed a recrystallized structure as shown by the photo-micrograph of Figure 3.
Fi~e test pieces taken from each of the products (A) and (~) were subjecled to a repeated bending test for ~atigue strength.
The results were as shown below.
:~ ~'7~5 o Method of measurement - A test piece was held horizontally with one end fastened by a stationary holder and the remaining free end of the test piece was vibrated in a vertical direction.
O = 2 a~ ( 1 ) wherein, ~ stands for the stated stress, Q stands for the distance the fastened point to the working point of force.
d stands for the diameter of the test piece, and E stands for the Youngts modulus (2.1 ~ 104kg/mm2) of the material.
The test piece was given a repeated bending with the amplitude calculated by the formula (1) shown above, with count taken of the bends given to the test piece until a fracture was sustained by the test piece.
o Test results Stated Number of repeated bends given until fracture 20 stress2 Product ~A) o~ Convention produc-t (B) _ Fracture sustained after Fracture sustained after 1.6 x 106 bends. 1.5 x 105 bends.
27 Fracture sustained after Fracture sustended after 3.8 x 106 bends. 2.4 x 105 bends.
24 No fracture sustained Fracture sustained after after 1.0 ~ 107 bends. 4.8 x 105 bends.
21 .~ " Fracture sustended a~ter 1.1 x 10~ bends.
18 .. .. No fracture sustained after _ __ _ 1.0 x 107 bends.
.11'7 As described above, owing to the annealing treatment which is performed in the form of a low-temperature working, the iron and steel materials produced according to the present invention retain a uniform flattened grain structure free from residual stress and incapable of recrystallization, and possess a hardness which is greater by 55% to 125% than that of con-~
ventional materials which have undergone complete annealing, Consequently they enjoy a notable enhancement in the fatigue strength against bending and vibrations. The materials, when used in fabricated products such as tubes and bars, preclude occurrence of cracks and fractures in the fastened portions, joined ends and so forth. The products of this invention, therefore, prove highly useful for industrial applications.
Claims (8)
1. A method of treating ferrous materials comprising subjecting the material to plastic deformation whereby a flattened grain structure is produced, and subsequently annealing the material in such a way as to retain the flattened grain structure.
2. A method according to claim 1, wherein annealing following plastic deformation is carried out at a particular temperature and for a period of time be-yond which structural recrystallization occurs.
3. A method according to claim 1, wherein the materials have a carbon content in the range 0.05% to 0.45% (by weight).
4. A method according to any one of claims 1 to 3, wherein the plastic deformation is effected by drawing at a reduction ratio within the range 20% to 60%.
5. A ferrous material having a uniform flattened grain structure which has been treated by the method according to claim 1.
6. Material according to claim 5 wherein the flattened grain structure is substantially free from recrystalli-zation.
7. Material according to claim 5 or claim 6, and in the form of a tube.
8. Material according to claim 5 or claim 6 and in the form of a bar.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP37323/55 | 1980-03-24 | ||
| JP3732380A JPS56133417A (en) | 1980-03-24 | 1980-03-24 | Iron and steel materials |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1178517A true CA1178517A (en) | 1984-11-27 |
Family
ID=12494444
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000373498A Expired CA1178517A (en) | 1980-03-24 | 1981-03-20 | Ferrous materials |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS56133417A (en) |
| AU (1) | AU6866881A (en) |
| BR (1) | BR8101746A (en) |
| CA (1) | CA1178517A (en) |
| DE (1) | DE3111249A1 (en) |
| FR (1) | FR2482136A1 (en) |
| GB (1) | GB2072703A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19854168C2 (en) * | 1997-06-11 | 2000-05-25 | Leico Werkzeugmaschb Gmbh & Co | Method for producing a toothed gear part |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2235243A (en) * | 1939-03-27 | 1941-03-18 | Republic Steel Corp | Ferrous metal article and method of producing same |
| US2293938A (en) * | 1939-06-14 | 1942-08-25 | Nat Tube Co | Tubular article |
| US3230118A (en) * | 1961-08-15 | 1966-01-18 | Screw & Bolt Corp Of America | Method of developing high physical properties in ferrous material and product produced thereby |
| US4018634A (en) * | 1975-12-22 | 1977-04-19 | Grotnes Machine Works, Inc. | Method of producing high strength steel pipe |
-
1980
- 1980-03-24 JP JP3732380A patent/JPS56133417A/en active Pending
-
1981
- 1981-03-20 CA CA000373498A patent/CA1178517A/en not_active Expired
- 1981-03-20 GB GB8108860A patent/GB2072703A/en not_active Withdrawn
- 1981-03-21 DE DE19813111249 patent/DE3111249A1/en not_active Withdrawn
- 1981-03-24 BR BR8101746A patent/BR8101746A/en unknown
- 1981-03-24 FR FR8105852A patent/FR2482136A1/en active Pending
- 1981-03-24 AU AU68668/81A patent/AU6866881A/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| BR8101746A (en) | 1981-09-29 |
| DE3111249A1 (en) | 1982-03-04 |
| GB2072703A (en) | 1981-10-07 |
| JPS56133417A (en) | 1981-10-19 |
| AU6866881A (en) | 1981-10-15 |
| FR2482136A1 (en) | 1981-11-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |