Curing damage in metallic materials by means of regenerative heat treatment

Kumanin, V. I.; Kovaleva, L. A.; Sokolova, M. L.

doi:10.1007/bf01189468

Cited by 5 publications

(5 citation statements)

References 1 publication

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“…A lot of research has been conducted on crack healing in inorganic and composite materials while less work has been performed on metals. The damage evolution in metals was analysed [3], and many kinds of heat treatment methods can be used to decrease the number of defects in metals after a long-term operation at high temperatures [4]. By TEM observation, a crack in α-Fe was found to be healed completely when the temperature was increased to a critical value of 1073 K [5].…”

Section: Introductionmentioning

confidence: 99%

Evolution of Internal Crack in BCC Fe under Compressive Loading

Wei

Jiang

Han

2012

JMP

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A molecular dynamics model has been developed to investigate the evolution of the internal crack of nano scale during heating or compressive loading in BCC Fe. The initial configuration does not contain any pre-existing dislocations. In the case of heating, temperature shows a significant effect on crack evolution and the critical temperature at which the crack healing becomes possible is 673 K. In the case of compressive loading, the crack can be healed at 40 K at a loading rate 0.025 × 1018 Pa·m<sup>1/2</sup>/s in 6 × 10<sup>-12 </sup>s. The diffusion of Fe atoms into the crack area results in the healing process. However, dislocations and voids appear during healing and their positions change continuously

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Section: Introductionmentioning

confidence: 99%

Evolution of Internal Crack in BCC Fe under Compressive Loading

Wei

Jiang

Han

2012

JMP

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“…The damage evolution in metals was analysed [4], and many heat treatment methods can be used to reduce the number of defects in metals after a long-term operation at high temperatures [5]. By TEM observation, a crack in α-Fe was found to be healed completely when the temperature was increased to a critical value of 1073K [6].…”

Section: Introductionmentioning

confidence: 99%

Modelling of the evolution of crack of nanoscale in iron

Wei

Jiang

Han

2013

Computational Materials Science

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Metal owns the ability of self-healing to some extent, and the ability of the internal crack healing is most desirable for improving the reliability of metal. A molecular dynamics simulation has been further developed to investigate the evolution of a nanoscale crack in body centred cubic Fe crystal under the conditions of heating or compressive pressure. When system temperature drops, the evolution of the crack that was at elevated temperature has been studied for the first time. N-body potential according to the embedded atom method has been adopted. The original nanoscale crack is expressed by removing some atoms in the centre of the cell, and the minimum vertical distance between the atoms on the top and bottom crack surfaces has been defined as Dm for assessing the process of crack evolution. The results show that a crack healing process can be accelerated significantly with an increase of temperature. When the system temperature decreases, Dm of the crack that was in healing process does not change significantly but fluctuates in a narrow range. This means that the crack healing is the result of Fe atoms diffusing into the crack area but not the thermal stress incurred in the simulation cell at elevated temperature. The pre-compressive pressure under the condition of both biaxial and uniaxial loadings can help promote the crack healing significantly and results in more uniform distribution of defects after healing. AbstractMetals own the ability of self-healing to some extent, and the ability of the internal crack healing is most desirable for improving the reliability of metals. A molecular dynamics simulation has been further developed to investigate the evolution of a nano scale crack in body centred cubic Fe crystal under the conditions of heating or compressive pressure. When system temperature drops, the evolution of the crack that was at elevated temperature has been studied for the first time. N-body potential according to the embedded atom method has been adopted. The original nano scale crack is expressed by removing some atoms in the centre of the cell, and the minimum vertical distance between the atoms on the top and bottom crack surfaces has been defined as D m for assessing the process of crack evolution. The results show that a crack healing process can be accelerated significantly with an increase of temperature. When the system temperature decreases, D m of the crack that was in healing process does not change significantly but fluctuates in a narrow range.This means that the crack healing is the result of Fe atoms diffusing into the crack area but not the thermal stress incurred in the simulation cell at elevated temperature. The pre compressive pressure under the condition of both biaxial and uniaxial loadings can help promote the crack healing significantly and results in more uniform distribution of defects after healing.

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“…Griffith [2] found that the cracking is not a "reversible" operation, but a very small crack may be healed if the temperature of the heat-treatment is high enough to bring the atoms on either side of the crack to within a mutual range by thermal agitation. Kumanin et al [3] analyzed the damage evolution in metals, and indicated that many types of heat treatment methods can be used to decrease the amount of defects in metals after a longterm operation at high temperature. Han et al [4] investigated the crack healing in 20MnMo steel.…”

Section: Introductionmentioning

confidence: 99%

Effects of Process Conditions on Crack Healing in 30Cr2Ni4MoV Steel during Hot Forging

Zhang

Lin

Zhu

et al. 2012

AMM

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Internal cracks in 30Cr2Ni4MoV steel were produced by compressing cylindrical sample with drilled hole. In order to consider the effects of deformation degree, temperature, strain rate and holding time on the crack healing, the hot compression tests were performed on Gleeble-1500 thermo-simulation machine under different process conditions. By in situ observation under optical microscope and scanning electron microscope, effects of process condition on crack healing and the behaviours of crack healing were revealed successfully: (1) the result of crack healing improves as the melt temperature, reduction and holding time increase, (2) the effect of crack healing decreases as the strain rate increases. By the energy dispersive spectroscopy, it is also found that the chemical composition of the healed crack area is different from that of the matrix.

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Curing damage in metallic materials by means of regenerative heat treatment

Cited by 5 publications

References 1 publication

Evolution of Internal Crack in BCC Fe under Compressive Loading

Evolution of Internal Crack in BCC Fe under Compressive Loading

Modelling of the evolution of crack of nanoscale in iron

Effects of Process Conditions on Crack Healing in 30Cr2Ni4MoV Steel during Hot Forging

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