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Title: Non-destructive residual stress distribution measurement in nano-structured ultrahigh-strenght gear steels.

Abstract

The well-established enhanced fatigue performance associated with beneficial compressive residual stresses has been broadly applied in the development of new engineering materials, particularly gear and bearing steels. Residual stress enhancement processes, such as shot/laser peening, have also been investigated to maximize their benefits on fatigue strength. However, the measurement of residual stress distributions still heavily relies on the conventional X-ray technique, involving destructive material removal, tedious data correction and time-consuming data collection, which slows new material design and process optimization. To overcome this problem, we employ novel, non-destructive synchrotron techniques with high-energy x-rays to measure the distribution of residual strain/stress in a laser-peened, ultrahigh-strength gear steel. This study will assist in process optimization, to achieve the desired residual stresses for selected applications. X-ray measurements were performed at the 1-ID beamline at the Advanced Photon Source (APS), Argonne National Laboratory. An x-ray energy of 76 keV and conical slit were used to create a diffraction volume of {approx} 20 x 20 x 150{micro}m{sup 3}. An area detector was placed after the conical slit to collect diffraction over a plane encompassing (nearly) the axial and normal strain directions. Cylindrical specimens (76 mm long, 9.525 mm diameter) were rotated during the measurement tomore » ensure a sufficiently large number of grains were irradiated. The steel, FerriumC67{reg_sign}, was designed utilizing thermodynamics-based strengthening models to achieve a new level of case hardness (67 HRc) and good core toughness, employing a 3nm M{sub 2}C carbide dispersion. After heat treatment, C67 was laser peened and subject to rolling contact fatigue (RCF) screening tests under the extreme Hertzian contact stress of 5.4 GPa. Both regions away from ('untested') and under wear tracks were studied for comparison. Four BCC reflections from martensite [(200), (211), (220) and (222)] were recorded and (211) was used for residual strain analysis. Strain components ({var_epsilon}{sub 11}, {var_epsilon}{sub 12} and {var_epsilon}{sub 22}) were obtained and the axial ({var_epsilon}{sub 11}) is plotted in Fig. 1 for unpeened and laser peened C67 samples. Large compressive axial strains were observed near-surface after peening. After cyclic loading the surface strain relaxed but a sub-surface maximum was formed, attributed to yielded material from the extreme cyclic loading. These strains were converted to stresses (not shown) via elastic constants and assuming equibiaxial strain ({var_epsilon}{sub 33} = {var_epsilon}{sub 11}).« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
971920
Report Number(s):
ANL/XFD/CP-118713
TRN: US1001411
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Conference
Resource Relation:
Conference: 5th International Conference on Synchrotron Radiation in Materials Science (SRMS 5); Jul. 30, 2006 - Aug. 2, 2006; Chicago, IL
Country of Publication:
United States
Language:
ENGLISH
Subject:
43 PARTICLE ACCELERATORS; 36 MATERIALS SCIENCE; ADVANCED PHOTON SOURCE; AFTER-HEAT; BEARINGS; CARBIDES; DIFFRACTION; DISTRIBUTION; HARDNESS; LASERS; MARTENSITE; OPTIMIZATION; REMOVAL; RESIDUAL STRESSES; ROLLING; SHOT PEENING; STEELS; STRAINS; STRESSES; SYNCHROTRON RADIATION; SYNCHROTRONS

Citation Formats

Qian, Y., Almer, J., Lienert, U., Tiemens, B., Olson, G. B., and Northwestern Univ. Non-destructive residual stress distribution measurement in nano-structured ultrahigh-strenght gear steels.. United States: N. p., 2006. Web.
Qian, Y., Almer, J., Lienert, U., Tiemens, B., Olson, G. B., & Northwestern Univ. Non-destructive residual stress distribution measurement in nano-structured ultrahigh-strenght gear steels.. United States.
Qian, Y., Almer, J., Lienert, U., Tiemens, B., Olson, G. B., and Northwestern Univ. Sun . "Non-destructive residual stress distribution measurement in nano-structured ultrahigh-strenght gear steels.". United States. doi:.
@article{osti_971920,
title = {Non-destructive residual stress distribution measurement in nano-structured ultrahigh-strenght gear steels.},
author = {Qian, Y. and Almer, J. and Lienert, U. and Tiemens, B. and Olson, G. B. and Northwestern Univ.},
abstractNote = {The well-established enhanced fatigue performance associated with beneficial compressive residual stresses has been broadly applied in the development of new engineering materials, particularly gear and bearing steels. Residual stress enhancement processes, such as shot/laser peening, have also been investigated to maximize their benefits on fatigue strength. However, the measurement of residual stress distributions still heavily relies on the conventional X-ray technique, involving destructive material removal, tedious data correction and time-consuming data collection, which slows new material design and process optimization. To overcome this problem, we employ novel, non-destructive synchrotron techniques with high-energy x-rays to measure the distribution of residual strain/stress in a laser-peened, ultrahigh-strength gear steel. This study will assist in process optimization, to achieve the desired residual stresses for selected applications. X-ray measurements were performed at the 1-ID beamline at the Advanced Photon Source (APS), Argonne National Laboratory. An x-ray energy of 76 keV and conical slit were used to create a diffraction volume of {approx} 20 x 20 x 150{micro}m{sup 3}. An area detector was placed after the conical slit to collect diffraction over a plane encompassing (nearly) the axial and normal strain directions. Cylindrical specimens (76 mm long, 9.525 mm diameter) were rotated during the measurement to ensure a sufficiently large number of grains were irradiated. The steel, FerriumC67{reg_sign}, was designed utilizing thermodynamics-based strengthening models to achieve a new level of case hardness (67 HRc) and good core toughness, employing a 3nm M{sub 2}C carbide dispersion. After heat treatment, C67 was laser peened and subject to rolling contact fatigue (RCF) screening tests under the extreme Hertzian contact stress of 5.4 GPa. Both regions away from ('untested') and under wear tracks were studied for comparison. Four BCC reflections from martensite [(200), (211), (220) and (222)] were recorded and (211) was used for residual strain analysis. Strain components ({var_epsilon}{sub 11}, {var_epsilon}{sub 12} and {var_epsilon}{sub 22}) were obtained and the axial ({var_epsilon}{sub 11}) is plotted in Fig. 1 for unpeened and laser peened C67 samples. Large compressive axial strains were observed near-surface after peening. After cyclic loading the surface strain relaxed but a sub-surface maximum was formed, attributed to yielded material from the extreme cyclic loading. These strains were converted to stresses (not shown) via elastic constants and assuming equibiaxial strain ({var_epsilon}{sub 33} = {var_epsilon}{sub 11}).},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}

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  • We investigated the residual stress depth profile near the surface of steel treated by laser peening without coating using X-ray diffraction at SPring-8. This investigation was carried out using a constant penetration depth sin2{psi} method. In this method, the sin2{psi} diagram is measured controlling both the {psi} angle and the X-ray penetration depth simultaneously with a combination of the {omega} and {chi} axes of the 4-circle goniometer. This method makes it possible to evaluate the residual stress and its depth profile in material with a stress gradient precisely and non-destructively. As a result, we confirmed that a compressive residual stressmore » was successfully formed all over the range of the depth profile in the steel treated properly by laser peening without coating.« less
  • No abstract prepared.
  • An experimental formula has been proposed for the estimation of bending fatigue strength of carburized gears. The derivation of the formula is briefly reviewed first, and the effectiveness of the formula is examined based on the comparison with many test results including shot peened gears. Except for some cases, the formula is verified to be effective for the approximate estimation of the fatigue strength. The formula also shows a way of enhancing fatigue strength by increasing surface hardness and residual stress. The enhancement of the strength is demonstrated quantitatively. The strength is enhanced about 300MPa by appropriate shot peening. Andmore » it can be improved still more by electropolishing. 25 refs.« less
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