WO2007069270A2 - Post forging process for enhancing fatigue strength of steel components - Google Patents
Post forging process for enhancing fatigue strength of steel components Download PDFInfo
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- WO2007069270A2 WO2007069270A2 PCT/IN2006/000425 IN2006000425W WO2007069270A2 WO 2007069270 A2 WO2007069270 A2 WO 2007069270A2 IN 2006000425 W IN2006000425 W IN 2006000425W WO 2007069270 A2 WO2007069270 A2 WO 2007069270A2
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- WIPO (PCT)
- Prior art keywords
- optimal stress
- grinding
- machining
- hardening
- drilling
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
Definitions
- This invention relates to a judicious combination of processes such as drilling, hardening, grinding and finishing for enhancing the fatigue strength of forged steel components of given specification that are subjected to dynamic stresses in various applications.
- Parameters influencing higher torsion and bending fatigue strength of forged steel components are clean steel that is free from inclusions, gas porosity, fine structure of pearlitic matrix with grain boundary ferrite, fine tempered martensitic structure at the induction hardened surface, good effective case depth, good t/r (effective case depth/fillet radius) ratio, higher residual compressive stresses and absence of reformed martensite near the holes in the component.
- the main object of the present invention is to provide optimal stress machining process to significantly enhance fatigue strength of components that are subjected to dynamic stresses.
- crankshafts used in automotive and diverse engine applications
- the present invention discloses a novel process for optimal stress machining to impart enhanced fatigue strength to forged steel components of given specification by judicious combination of processes involving drilling, hardening, grinding and finishing.
- the judicious combination of the process sequence involves solid carbide drilling, followed by induction hardening, twin-wheel CBN grinding and superfinishing to GBQ levels.
- the drilling operation in the present invention ensures the straightness and surface finish of holes and absence of any "reformed martensite" in the process of drilling.
- L/D (length to diameter of drilled hole) ratio may vary from 1 to 30 with most preferable value at about 20.
- Lubrication during the drilling process is carried out at the flow rate up to15 ml/hr, more preferably at 10 ml/hr (MQL).
- the output parameters characterizing the process are surface finish and hole integrity.
- the surface finish is ⁇ 7 ⁇ R a , preferably 1.5 - 3 ⁇ R a . Integrity of the exposed surface is maintained with discontinuity, such as spiral cut caused during drilling process, not being deeper than 20 microns, preferably not deeper than 2 microns.
- hardening is carried out by induction route with power pulsing capability and polymer quenching.
- Heating cycle is less than 40 seconds, preferably between 16-18 seconds.
- Quench time ranges from 15-30 seconds and is preferably 18-20 seconds.
- Power applied may range from 60-2000 KVA.
- Process of hardening results in the output that has "fine tempered martensite” microstructure after induction hardening and tempering and a surface that has no cracks with a hardness of 48-60 HRC (Rockwell 1 C scale), preferably 52-58 HRC.
- hardening precedes grinding as CBN grinding employed in the process of the current invention also has the advantage of not deteriorating the compressive residual stresses created during induction hardening.
- the twin CBN wheel grinding process involves cutting speeds ranging up to 120 m/sec while the most preferred speed is 90 m/sec.
- the feed rates may range from 0.05-0.5 mm/min and preferably maintained at 0.2 mm/min.
- the grinding process result in a surface finish of 0.3 -1.0 ⁇ R a , preferably ⁇ 0.5 ⁇ R a , without any grinding burns. While it is difficult to achieve straightness with conventional grinding, the process of the present invention achieves straightness of 3-4 ⁇ without a tail, while crowning is 2-4 ⁇ .
- Billets of forging quality of steel containing C: 0.35-0.4%, Mn 1.3-1.5%, Si 0.35-0.7%, P 0.03 % (max), S 0.015 - 0.03%, Cr 0.1 0.2%, Ni 0.2 %(max), Al 0.01-0.04%, V 0.05 - 0.12%, Nb 0.05% (max), N2 100 ppm-170 ppm was used.
- the billets were forged into crankshafts under the normal closed die forging process and the forgings were 'control cooled'.
- Resultant part with predominantly pearlitic microstructure with ferrite network had hardness of 3.9-3.6 mm (241-285 BHN) and following mechanical properties against the limits specified by the intended application
- Hardening was done with heating time of 14 seconds on pins and 18 seconds on journals, quench time of 20 seconds on pins and 25 seconds on journals with a quench flow rate of 300 liters per minute.
- the crankshafts were then subjected to twin wheel CBN grinding process carried out at cutting speeds of 110m/sec and finish feed rates of 0.2mm/min followed by super finishing with cutting speed of 2m/sec and finish time of 5 seconds.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
- Heat Treatment Of Steel (AREA)
- Forging (AREA)
Abstract
This invention relates to a judicious combination of processes such as drilling, hardening, grinding and finishing for enhancing the fatigue strength of forged steel components of given specification that are subjected to dynamic stresses in various applications. It provides a process for optimal stress machining process to significantly enhance fatigue strength of components that are subjected to dynamic stresses. It further provides an integrated post-forging process that is applicable to forging quality steel components including crank shafts with significant enhancement of torsion and bending fatigue strengths for applications in which such components are subjected to dynamic stress of forging quality steel components for applications in which such components are subjected to dynamic stress. The process sequence involves solid carbide drilling, followed by induction hardening, twin-wheel CBN grinding and superfinishing to GBQ levels.
Description
Post forging process for enhancing fatigue strength of steel components
Field of the invention
This invention relates to a judicious combination of processes such as drilling, hardening, grinding and finishing for enhancing the fatigue strength of forged steel components of given specification that are subjected to dynamic stresses in various applications.
Background of the Invention
Steel is used to fabricate different components with specified characteristics such as fatigue strength, bending strength etc. depending upon the requirements of the application in industries such as automotive, engines, oil and gas. In the Automotive industry, for example, .engine and transmission components such as camshafts, crankshafts, drive shafts, and transmission shafts are subjected to high dynamic and cyclic loads and therefore require higher fatigue strengths. Number of components used in such applications are forged out of steel.
Parameters influencing higher torsion and bending fatigue strength of forged steel components are clean steel that is free from inclusions, gas porosity, fine structure of pearlitic matrix with grain boundary ferrite, fine tempered martensitic structure at the induction hardened surface, good effective case depth, good t/r (effective case depth/fillet radius) ratio, higher residual compressive stresses and absence of reformed martensite near the holes in the component.
Holes, such as galleries for circulation of lubricating oil in case of crankshafts, have to be drilled in many components that are subjected to high dynamic and cyclic loads. In such cases, number of failures are known to occur in practice near the holes as the holes, in a given geometry of the components, become the weakest section and hence susceptible to be the point of origin of cracks due to torsional fatigue stresses. The fatigue strength of components of given specification is
i
therefore influenced by such holes. The process of drilling holes therefore becomes critical in enhancing fatigue strength. Traditionally holes are drilled using high-speed steel drills or following the "gun drilling" process. These conventional processes provide holes of certain geometric consistency and size.
Hardening steel parts is a fairly well established process that is carried out by through hardening or case hardening processes such as induction hardening or nitriding, based on the steel chemistry and desired end application
US Patent No. 5,906,691 discloses a method for induction hardened micro alloy steel having enhanced fatigue strength properties achieved by induction hardening micro alloy steel crankshaft. The main deliverable of the process is in the controlled alloy chemistry and low tempering temperature, which is principally responsible for a substantial increase in bending fatigue strength over conventional carbon grade steels. The process involves induction hardening of micro alloy steel of a specific grade in order to achieve better bending fatigue strength. However this process does not address issues related to torsion fatigue strength. It also does not teach post-forging machining processes as a means to increase fatigue strength.
A publication by Bertoni LJ and Volpe ZE in Met Constr Mec v 101 n 11 Nov 1969 p527-32 outlines the factors, which may cause fatigue and presents a study of fatigue cracks, conducted at the Naval Laboratories in Buenos Aires, Argentina. The results show a close relationship between forging and subsequent machining, and the susceptibility to fatigue of the steel employed. However, this publication does not teach how to process forged steel components so as to achieve higher fatigue strength.
Another publication by Davies TD, Hurd NJ, Irving PE, Whittaker D in The
Metallurgical Society/ AIME pp 435-460, 1987 discusses the fatigue and machinability performance of air-cooled forging steels. In this review, it is shown that, while considerable effort has been expended in optimizing static strength
properties, engineering properties such as fatigue and machinability have been neglected. A detailed study has been made of fatigue and machinability properties in these steels. It is found that fatigue properties are strongly dependent on prior austenite grain size in addition to the usual dependency on static strength level. At the finish forging temperatures used in commercial practice, prior austenite grain size is such that fatigue strength is reduced by a factor of 15% with respect to conventional quenched and tempered steels. Machinability studies show that, at the higher static strength levels required to counter this effect, any machinability difficulties can be overcome with an alloy, which is sulphur treated and has calcium modification. This publication too is silent on any post forging processes that may be employed to enhance fatigue strength.
. While all disclosures in prior art have resulted in achieving improvement in fatigue strength, the limitations have been that the improvement is marginal in quantifiable terms and is restricted to "micro alloy steel components". Further there is no insight on how the fatigue strength can be enhanced in forged steel components that are subjected to dynamic stresses by post forging process.
It is a longstanding need of the industry to provide industrially applicable cost effective post-forging processes to enhance the fatigue strength of components that are subjected to dynamic stresses
Summary of the Invention
The main object of the present invention is to provide optimal stress machining process to significantly enhance fatigue strength of components that are subjected to dynamic stresses.
It is another object of the invention to provide integrated post-forging process that is applicable to forging quality steel components for applications in which such components are subjected to dynamic stress.
It is another object of the invention to significantly enhance torsion and bending fatigue strengths of forging quality steel components for applications in which such components are subjected to dynamic stress.
It is yet another object of the invention to prepare forged components such as crankshafts used in automotive and diverse engine applications
Detailed description of invention
There are several processes such as drilling, hardening, turning, grinding, finishing etc. that are routinely used in the machining of forged components used in various industries. Such processes generally bring about changes in the components to achieve end results in terms of specified form, fit and tolerance. However, as discussed in the prior art, there are no known industrially viable processes that exploit judicious combination of such machining processes to enhance fatigue strengths of forged steel components that are subjected to dynamic stresses.
The present invention discloses a novel process for optimal stress machining to impart enhanced fatigue strength to forged steel components of given specification by judicious combination of processes involving drilling, hardening, grinding and finishing. In a preferred embodiment of the present invention, the judicious combination of the process sequence involves solid carbide drilling, followed by induction hardening, twin-wheel CBN grinding and superfinishing to GBQ levels.
The drilling operation in the present invention ensures the straightness and surface finish of holes and absence of any "reformed martensite" in the process of drilling.
The optimized stress machining process of the present invention involves high speed, high feed solid carbide drilling with parametric programming and "through- coolant" system. This significantly improves the two parameters stated and results
in a high integrity and superior texture of the hole. Straightness and surface finish of the hole achieved by the specific application of this process contribute to enhanced fatigue strength of the components. Additionally, the process eliminates occurrence of "reformed martensite" or any stress risers in the hole region. The hole drilling process is carried out at cutting speeds ranging from 30 to120 m/min. Preferred range of the cutting speed is 50 to100 m/min. The feed rates may range from 300 to 1000 mm/min, preferably from 500 to 1000 mm/min. L/D (length to diameter of drilled hole) ratio may vary from 1 to 30 with most preferable value at about 20. Lubrication during the drilling process is carried out at the flow rate up to15 ml/hr, more preferably at 10 ml/hr (MQL).
The output parameters characterizing the process are surface finish and hole integrity. The surface finish is < 7μRa, preferably 1.5 - 3 μRa. Integrity of the exposed surface is maintained with discontinuity, such as spiral cut caused during drilling process, not being deeper than 20 microns, preferably not deeper than 2 microns.
In a preferred embodiment of the present invention, hardening is carried out by induction route with power pulsing capability and polymer quenching. Heating cycle is less than 40 seconds, preferably between 16-18 seconds. Quench time ranges from 15-30 seconds and is preferably 18-20 seconds. Power applied may range from 60-2000 KVA.
Process of hardening results in the output that has "fine tempered martensite" microstructure after induction hardening and tempering and a surface that has no cracks with a hardness of 48-60 HRC (Rockwell 1C scale), preferably 52-58 HRC.
Grinding process is a well-known multipoint form-generating process. However the present invention involves a process of twin wheel CBN grinding instead of conventional abrasive grinding. This process has the advantage of being carried out
at two times the cutting speed and almost three times the feed rates of conventional wheel grinding while inducing minimal stress and heat generation.
It is the combination of the hardening and the grinding that makes the post-forging machining process distinctive in achieving higher fatigue strength. While the steps of hardening and grinding are interchangeable, in the preferred embodiment of the optimal stress machining process, hardening precedes grinding as CBN grinding employed in the process of the current invention also has the advantage of not deteriorating the compressive residual stresses created during induction hardening.
The twin CBN wheel grinding process involves cutting speeds ranging up to 120 m/sec while the most preferred speed is 90 m/sec. The feed rates may range from 0.05-0.5 mm/min and preferably maintained at 0.2 mm/min.
For enhancement of fatigue strength, the grinding process result in a surface finish of 0.3 -1.0μRa, preferably ~0.5 μRa, without any grinding burns. While it is difficult to achieve straightness with conventional grinding, the process of the present invention achieves straightness of 3-4 μ without a tail, while crowning is 2-4 μ.
Superfinishing to GBQ (Generated Bearing Quality) level is achieved through fine- tuning of the post-grinding operation focused on fatigue strength improvement through optimal feed rates with cutting speeds of 0.6-3.0 m/sec. Further the process cycle time is 3-1 δseconds.
Superfinishing as described here results in exceptional surface finish of <0.4 μRa, preferably 0.04-0.09 μRa without any cross hatch.
It may be noted that such judicious combination and sequencing of processes to result in the surprising enhancement of fatigue strengths in forged steel components that are subjected to dynamic stresses in applications has not been taught in prior art. This invention is now illustrated with a non-limiting example:
Example 1
Billets of forging quality of steel containing C: 0.35-0.4%, Mn 1.3-1.5%, Si 0.35-0.7%, P 0.03 % (max), S 0.015 - 0.03%, Cr 0.1 = 0.2%, Ni 0.2 %(max), Al 0.01-0.04%, V 0.05 - 0.12%, Nb 0.05% (max), N2 100 ppm-170 ppm was used.
The billets were forged into crankshafts under the normal closed die forging process and the forgings were 'control cooled'. Resultant part with predominantly pearlitic microstructure with ferrite network had hardness of 3.9-3.6 mm (241-285 BHN) and following mechanical properties against the limits specified by the intended application
These forgings were subjected to optimal stress machining process of the present invention.
Oil holes of the given geometry (L=160mm, D=6.5mm) were first drilled at a cutting speed of 160m/min and feed rate of 600mm/min. This was followed by induction hardening with power (0.5MVA) pulsing technique and polymer quenching.
Hardening was done with heating time of 14 seconds on pins and 18 seconds on journals, quench time of 20 seconds on pins and 25 seconds on journals with a quench flow rate of 300 liters per minute. The crankshafts were then subjected to twin wheel CBN grinding process carried out at cutting speeds of 110m/sec and
finish feed rates of 0.2mm/min followed by super finishing with cutting speed of 2m/sec and finish time of 5 seconds.
This resulted in parts exhibiting substantial increase in bending and torsion fatigue strength without influencing any of the other desired properties as follows:
Characterization of oil hole surface was done by detailed microstructure / metallographic examination which showed absence of reformed martensite. This together with high residual compressive stresses in the part is a distinctive feature of the said product made by the process of this invention.
Claims
1. A process for optimal stress machining to impart enhanced fatigue strength to forged steel components of given specification by judicious sequencing of processes involving drilling, hardening, grinding and finishing.
2. A process for optimal stress machining as claimed in claim 1 wherein the process sequence involves solid carbide drilling, followed by induction hardening, twin-wheel CBN grinding and superfinishing to GBQ levels.
3. A process for optimal stress machining as claimed in claims 1-2 wherein the drilling operation ensures the straightness and surface finish of holes and absence of any "reformed martensite" in the process of drilling.
4. A process for optimal stress machining as claimed in claims 1-2 wherein the high feed solid carbide drilling operation is carried out at high speed, with parametric programming and "through-coolant" system.
5. A process for optimal stress machining as claimed in claims 1-4 wherein the hole drilling process is carried out at cutting speeds ranging from 30 to120 m/min, preferably 50 to100 m/min, with feed rates from 300 to 1000 mm/min, preferably 500 to 1000 mm/min..
6. A process for optimal stress machining as claimed in claims 1-5 wherein the L/D (length to diameter of drilled hole) ratio of the hole varies from 1 to 30.
7. A process for optimal stress machining as claimed in claims 1-6 wherein lubrication during the drilling process is carried out at the flow rate up to15 ml/hr.
8. A process for optimal stress machining as claimed in claims 1-7 wherein the surface finish is < 7μRa, preferably 1.5 - 3 μRa and integrity of the exposed surface is maintained with discontinuity, such as spiral cut caused during drilling process, not being deeper than 20 microns.
9. A process for optimal stress machining as claimed in claims 1-2 wherein the hardening is carried out by induction route with power pulsing capability and polymer quenching.
10. A process for optimal stress machining as claimed in claims 1-2 & 9 wherein the heating cycle is less than 40 seconds, preferably between 16-18 seconds, qench time from 15-30 seconds and applied power of 60-2000 KVA.
11. A process for optimal stress machining as claimed in claims 1-2, 9-10, wherein the process of hardening results in the output that has "fine tempered martensite" microstructure after induction hardening and tempering and a surface without cracks with a hardness of 48-60 HRC preferably 52-58
HRC.
12. A process for optimal stress machining as claimed in claims 1-2 wherein the process of twin wheel CBN grinding is carried out at two times the cutting speed and almost three times the feed rates of conventional wheel grinding while inducing minimal stress and heat generation.
13. A process for optimal stress machining as claimed in claims 1-2 wherein the sequence of the steps of hardening and grinding are interchangeable.
14. A process for optimal stress machining as claimed in claims 1-2 wherein the step of hardening precedes grinding.
15. A process for optimal stress machining as claimed in claims 1-2, 12-14 wherein the twin CBN wheel grinding involves cutting speeds ranging up to 120 m/sec at feed rates of 0.05-0.5 mm/min.
16. A process for optimal stress machining as claimed in claims 1-2, 12-15 wherein the grinding process results in surface finish of 0.3 -1.0μRa, preferably -0.5 μRa, and straightness of 3-4 μ without a tail, crowning of 2-4 μ without grinding burns.
17. A process for optimal stress machining as claimed in claims 1-2 wherein the superfinishing to GBQ (Generated Bearing Quality) level is achieved at cutting speeds of 0.6-3.0 m/sec and process cycle time is 3-15 seconds.
18. A process for optimal stress machining as claimed in claims 1-2 and 17 wherein the superfinishing results in surface finish of <0.4 μRa, preferably 0.04-0.09 μRa without cross hatch.
19. A process for optimal stress machining as claimed in claims 1-18 wherein crankshafts produced from forging quality of steel containing C: 0.35-0.4%,
Mn 1.3-1.5%, Si 0.35-0.7%, P 0.03 % (max), S 0.015 - 0.03%, Cr 0.1 = 0.2%, Ni 0.2 %(max), Al 0.01-0.04%, V 0.05 - 0.12%, Nb 0.05% (max), N2 100 ppm-170 ppm subjected to drilling at a cutting speed of 160m/min and feed rate of 6Q0mm/min to result in holes of L=160mm, D=6.5mm followed by induction hardening with power (0.5MVA) pulsing technique and polymer quenching, hardening with heating time of 14 seconds on pins and 18 seconds on journals, quench time of 20 seconds on pins and 25 seconds on journals with a quench flow rate of 300 liters per minute, then subjecting to twin wheel CBN grinding process carried out at cutting speeds of 110m/sec and finish feed rates of 0.2mm/min followed by super finishing with cutting speed of 2m/sec and finish time of 5 seconds.
20. Crankshafts with predominantly pearlitic microstructure with ferrite network and hardness of 3.9-3.6 mm (241-285 BHN) and mechanical properties
Y.S (0.2 % PS) of alteast 632 Map, U.T.S of at least 939.1 Mpa, % E1 (G.I =5d) of at least 13% and % RA of at least 44% .
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IN1011/MUM/2005 | 2005-10-04 | ||
| IN1011MU2005 | 2005-10-04 |
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| Publication Number | Publication Date |
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| WO2007069270A2 true WO2007069270A2 (en) | 2007-06-21 |
| WO2007069270A3 WO2007069270A3 (en) | 2009-04-16 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/IN2006/000425 WO2007069270A2 (en) | 2005-10-04 | 2006-10-03 | Post forging process for enhancing fatigue strength of steel components |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108982276A (en) * | 2018-09-25 | 2018-12-11 | 中车青岛四方机车车辆股份有限公司 | A kind of metal welding process dynamic stress testing method and device |
| EP3401412A4 (en) * | 2016-01-08 | 2019-07-17 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Large crankshaft |
| WO2022065425A1 (en) * | 2020-09-28 | 2022-03-31 | 日本製鉄株式会社 | Crankshaft |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5000760A (en) * | 1988-07-22 | 1991-03-19 | Showa Denka K.K. | CBN abrasive-grains, method for producing the same, and grinding wheel |
| US5906691A (en) * | 1996-07-02 | 1999-05-25 | The Timken Company | Induction hardened microalloy steel having enhanced fatigue strength properties |
-
2006
- 2006-10-03 WO PCT/IN2006/000425 patent/WO2007069270A2/en active Application Filing
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5000760A (en) * | 1988-07-22 | 1991-03-19 | Showa Denka K.K. | CBN abrasive-grains, method for producing the same, and grinding wheel |
| US5906691A (en) * | 1996-07-02 | 1999-05-25 | The Timken Company | Induction hardened microalloy steel having enhanced fatigue strength properties |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3401412A4 (en) * | 2016-01-08 | 2019-07-17 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Large crankshaft |
| CN108982276A (en) * | 2018-09-25 | 2018-12-11 | 中车青岛四方机车车辆股份有限公司 | A kind of metal welding process dynamic stress testing method and device |
| WO2022065425A1 (en) * | 2020-09-28 | 2022-03-31 | 日本製鉄株式会社 | Crankshaft |
| CN116323992A (en) * | 2020-09-28 | 2023-06-23 | 日本制铁株式会社 | Crankshaft |
| JP7462781B2 (en) | 2020-09-28 | 2024-04-05 | 日本製鉄株式会社 | Crankshaft |
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| Publication number | Publication date |
|---|---|
| WO2007069270A3 (en) | 2009-04-16 |
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