Pub Date : 1900-01-01DOI: 10.1179/MSC.1969.3.1.190
R. Haynes, P. Maddocks
Abstract True stress/true strain curves have been determined for two fine-grained (α + β) titanium alloys containing various amounts of hydrogen, which was present either in solid solution or in solid solution and as a film-like hydride precipitate. In hydride-free specimens three stages, with high, low, and intermediate work-hardening exponents, are identified in the work-hardening of the alloys. The three stages, in order of occurrence, are attributed to partial plastic deformation, easy glide, and parabolic hardening. The presence of hydride lowers the initial flow stress, extends the first stage, eliminates the second stage, and lowers the work-hardening exponent of the third stage of work-hardening. These changes are believed to be caused by the hydride particles acting as stress concentrators, thus enabling localized plastic deformation to occur at low macroscopic stress levels and inducing complex slip at an early stage in work-hardening. Hydride precipitate also causes loss of ductility by markedl...
{"title":"The Effect of Hydrogen on the Work-Hardening and Fracture Behaviour of Titanium–Low-Aluminium–Low-Manganese Alloys","authors":"R. Haynes, P. Maddocks","doi":"10.1179/MSC.1969.3.1.190","DOIUrl":"https://doi.org/10.1179/MSC.1969.3.1.190","url":null,"abstract":"Abstract True stress/true strain curves have been determined for two fine-grained (α + β) titanium alloys containing various amounts of hydrogen, which was present either in solid solution or in solid solution and as a film-like hydride precipitate. In hydride-free specimens three stages, with high, low, and intermediate work-hardening exponents, are identified in the work-hardening of the alloys. The three stages, in order of occurrence, are attributed to partial plastic deformation, easy glide, and parabolic hardening. The presence of hydride lowers the initial flow stress, extends the first stage, eliminates the second stage, and lowers the work-hardening exponent of the third stage of work-hardening. These changes are believed to be caused by the hydride particles acting as stress concentrators, thus enabling localized plastic deformation to occur at low macroscopic stress levels and inducing complex slip at an early stage in work-hardening. Hydride precipitate also causes loss of ductility by markedl...","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"16 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131859227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1179/030634568790443486
C. Horton, N. Thompson, C. Beevers
AbstractBicrystals of zinc containing basal tilt boundaries of controlled orientation have been tested in simple shear over the range 320–390° C. Rapid grain-boundary sliding was observed in the absence of macroscopic trans crystalline slip. This “pure” grain-boundary sliding was accompanied by the emission of dislocations from the sliding boundaries and the creation of substructure in the crystalline regions adjacent to the boundaries. Grain-boundary slide-hardening was often noted in the absence of observable grain-boundary cusps or irregularities. By assuming a sliding-rate law of the form έ = Aσnt(m−1) exp( − Qs/KT) and by using differential test methods, values were obtained for the apparent activation energy (Qs ) and the stress parameter (n) for the “pure” grain-boundary sliding. The values Qs = 31 ± 5 (kcal/mole) and n = 4.5 ± 1.8 give strong support to the general conclusion that “pure” grain-boundary sliding is controlled by the case with which dislocations can be emitted by a sliding boundary a...
{"title":"“Pure” Grain-Boundary Sliding in Zinc Bicrystals","authors":"C. Horton, N. Thompson, C. Beevers","doi":"10.1179/030634568790443486","DOIUrl":"https://doi.org/10.1179/030634568790443486","url":null,"abstract":"AbstractBicrystals of zinc containing basal tilt boundaries of controlled orientation have been tested in simple shear over the range 320–390° C. Rapid grain-boundary sliding was observed in the absence of macroscopic trans crystalline slip. This “pure” grain-boundary sliding was accompanied by the emission of dislocations from the sliding boundaries and the creation of substructure in the crystalline regions adjacent to the boundaries. Grain-boundary slide-hardening was often noted in the absence of observable grain-boundary cusps or irregularities. By assuming a sliding-rate law of the form έ = Aσnt(m−1) exp( − Qs/KT) and by using differential test methods, values were obtained for the apparent activation energy (Qs ) and the stress parameter (n) for the “pure” grain-boundary sliding. The values Qs = 31 ± 5 (kcal/mole) and n = 4.5 ± 1.8 give strong support to the general conclusion that “pure” grain-boundary sliding is controlled by the case with which dislocations can be emitted by a sliding boundary a...","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132262993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1179/MSC.1970.4.1.180
D. Lloyd, A. P. Greenough
AbstractA preliminary study has been made of the relationship between dislocation substructure and the rate of nucleation and propagation of the fatigue crack in α-iron, by applying the stress to the annealed metal in different ways, or by making specimens from material that had been cold worked, hot rolled, or deformed by creep. Applying the full stress to the annealed metal at the first cycle, as compared with gradually building up the stress over a few thousand cycles, greatly reduced the life to fracture and considerably changed both the dislocation substructure, as revealed by transmission electron microscopy, and the nature of the slip-bands observed on the specimen surface. In some cases the yield point of the cold-worked or hot-rolled material was still falling when fatigue fracture occurred. Surface cracking remaining after creep was the significant factor reducing subsequent fatigue life. Neither the substructure nor the voids produced during creep seemed to influence fatigue-crack nucleation or...
{"title":"Some Factors that Influence the Fatigue Behaviour of Alpha-Iron","authors":"D. Lloyd, A. P. Greenough","doi":"10.1179/MSC.1970.4.1.180","DOIUrl":"https://doi.org/10.1179/MSC.1970.4.1.180","url":null,"abstract":"AbstractA preliminary study has been made of the relationship between dislocation substructure and the rate of nucleation and propagation of the fatigue crack in α-iron, by applying the stress to the annealed metal in different ways, or by making specimens from material that had been cold worked, hot rolled, or deformed by creep. Applying the full stress to the annealed metal at the first cycle, as compared with gradually building up the stress over a few thousand cycles, greatly reduced the life to fracture and considerably changed both the dislocation substructure, as revealed by transmission electron microscopy, and the nature of the slip-bands observed on the specimen surface. In some cases the yield point of the cold-worked or hot-rolled material was still falling when fatigue fracture occurred. Surface cracking remaining after creep was the significant factor reducing subsequent fatigue life. Neither the substructure nor the voids produced during creep seemed to influence fatigue-crack nucleation or...","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"184 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133332042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Tensile tests have been conducted at 300 and 500° C on specimens of unidirectionally grown aluminium–CuAl2 eutectic of various orientations and at 300 and 400° C on polycrystalline samples of this alloy. The tensile results, deformation and failure mechanisms, and spheroidization phenomena are described.
{"title":"Tensile Deformation at High Temperatures of Unidirectionally Grown and Polycrystalline Aluminium–CuAl2 Eutectic","authors":"B. R. Butcher, G. Weatherly, H. R. Pettit","doi":"10.1179/MSC.1969.3.1.7","DOIUrl":"https://doi.org/10.1179/MSC.1969.3.1.7","url":null,"abstract":"Abstract Tensile tests have been conducted at 300 and 500° C on specimens of unidirectionally grown aluminium–CuAl2 eutectic of various orientations and at 300 and 400° C on polycrystalline samples of this alloy. The tensile results, deformation and failure mechanisms, and spheroidization phenomena are described.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133503104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1179/030634571790439748
J. Barford, G. Willoughby
Abstract The published data on the creep and rupture strength of low-alloy ferritic steels are critically examined and it is concluded that there is no evidence that maximum strength accrues from a fully upper bainite structure. The creep strength, over a range of stress, of samples of one cast of low-alloy Cr-Mo-V steel in various structural conditions has been examined. It is shown that there is no gain in strength (primary creep strain or secondary-creep rate) to be obtained by increasing the bainite content above ∼20% at 11 hbar and 575°C (848 K). At higher stresses, creep strength improves up to ∼60% bainite. The stress-dependence of creep is structure-sensitive and its variation indicates that at itresses <∼11 hbar material containing ∼20–30 % bainite will have a lower secondary-creep rate than fully bainitic structures.
{"title":"Effect of Structure on Creep Strength of a Low-Alloy Cr-Mo-V Steel","authors":"J. Barford, G. Willoughby","doi":"10.1179/030634571790439748","DOIUrl":"https://doi.org/10.1179/030634571790439748","url":null,"abstract":"Abstract The published data on the creep and rupture strength of low-alloy ferritic steels are critically examined and it is concluded that there is no evidence that maximum strength accrues from a fully upper bainite structure. The creep strength, over a range of stress, of samples of one cast of low-alloy Cr-Mo-V steel in various structural conditions has been examined. It is shown that there is no gain in strength (primary creep strain or secondary-creep rate) to be obtained by increasing the bainite content above ∼20% at 11 hbar and 575°C (848 K). At higher stresses, creep strength improves up to ∼60% bainite. The stress-dependence of creep is structure-sensitive and its variation indicates that at itresses <∼11 hbar material containing ∼20–30 % bainite will have a lower secondary-creep rate than fully bainitic structures.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131933745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1179/MSC.1967.1.1.198
P. Goodhew, P. Dobson, R. Smallman
AbstractThe extrinsic stacking-fault energy of aluminium has been determined from the isothermal annealing of double-faulted dislocation loops in the electron microscope and found to be 30% greater than the intrinsic energy. The observed rarity of extrinsic faulting in thin foils is accounted for in terms of a nucleation barrier to the formation of an extrinsic fault. Several previous observations of extrinsic faults, some of which have been taken to imply a higher extrinsic stacking-fault energy, are re-examined in the light of this barrier.
{"title":"Extrinsic Stacking-Fault Energies in F.C.C. Materials","authors":"P. Goodhew, P. Dobson, R. Smallman","doi":"10.1179/MSC.1967.1.1.198","DOIUrl":"https://doi.org/10.1179/MSC.1967.1.1.198","url":null,"abstract":"AbstractThe extrinsic stacking-fault energy of aluminium has been determined from the isothermal annealing of double-faulted dislocation loops in the electron microscope and found to be 30% greater than the intrinsic energy. The observed rarity of extrinsic faulting in thin foils is accounted for in terms of a nucleation barrier to the formation of an extrinsic fault. Several previous observations of extrinsic faults, some of which have been taken to imply a higher extrinsic stacking-fault energy, are re-examined in the light of this barrier.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132735326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1179/MSC.1967.1.1.104
R. Wasilewski, S. R. Butler, J. Hanlon
Abstract The structural transformation of the CsCl-type compound TiNi has been investigated by X-ray-diffraction, calorimetric, and metallographic methods. The transition is a first-order one, with a latent heat of 370 ± 20 cal/g-atom. It occurs rapidly and with small hysteresis in bulk material, the transition temperature varying with composition within the range 48–52 at.-%nickel, and its martensitic character was confirmed by metallographic and electron-microscope observations. The martensite (low-temperature) structure is probably of low symmetry. There is some evidence that different transition products are formed on either side of the stoichiometry. Oxygen level significantly affects the transition behaviour.
{"title":"On the Martensitic Transformation in TiNi","authors":"R. Wasilewski, S. R. Butler, J. Hanlon","doi":"10.1179/MSC.1967.1.1.104","DOIUrl":"https://doi.org/10.1179/MSC.1967.1.1.104","url":null,"abstract":"Abstract The structural transformation of the CsCl-type compound TiNi has been investigated by X-ray-diffraction, calorimetric, and metallographic methods. The transition is a first-order one, with a latent heat of 370 ± 20 cal/g-atom. It occurs rapidly and with small hysteresis in bulk material, the transition temperature varying with composition within the range 48–52 at.-%nickel, and its martensitic character was confirmed by metallographic and electron-microscope observations. The martensite (low-temperature) structure is probably of low symmetry. There is some evidence that different transition products are formed on either side of the stoichiometry. Oxygen level significantly affects the transition behaviour.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121924960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1179/030634571790439487
C. V. D. Wekken, R. Taggart, D. H. Polonis
AbstractThe changes in the electrical resistivity of nickel-rich Ni-Nb alloys due to the formation of short-range order exhibit an anomalous dependence on the solute concentration. This anomaly can be explained by the formation of embryos of long-range order of the type Ni8Nb in alloys approaching the NisNb composition and near the critical temperature for long-range order. In the absence of a critical concentration of quenched-in vacancies, short-range-order formation only has been detected during ageing below the critical temperature.
{"title":"Short-Range Order and the Nucleation of Long-Range Order in Ni-Rich Nickel-Niobium Alloys","authors":"C. V. D. Wekken, R. Taggart, D. H. Polonis","doi":"10.1179/030634571790439487","DOIUrl":"https://doi.org/10.1179/030634571790439487","url":null,"abstract":"AbstractThe changes in the electrical resistivity of nickel-rich Ni-Nb alloys due to the formation of short-range order exhibit an anomalous dependence on the solute concentration. This anomaly can be explained by the formation of embryos of long-range order of the type Ni8Nb in alloys approaching the NisNb composition and near the critical temperature for long-range order. In the absence of a critical concentration of quenched-in vacancies, short-range-order formation only has been detected during ageing below the critical temperature.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"15 7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120989645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1179/MSC.1967.1.1.172
R. Lagneborg
AbstractBreaks in the stress/rupture time and stress/creep rate relation are known to occur during high-temperature creep. In the present work these deflections are explained in terms of different stress-dependences of the intracrystalline deformation rate and the rate of grain-boundary sliding. The transition from trans- to intercrystalline fracture, which coincides, at least approximately, with these breaks, is suggested to be due to the increased grain-boundary sliding at stresses below the break.
{"title":"Deviations from Linearity in Creep-Rupture Curves","authors":"R. Lagneborg","doi":"10.1179/MSC.1967.1.1.172","DOIUrl":"https://doi.org/10.1179/MSC.1967.1.1.172","url":null,"abstract":"AbstractBreaks in the stress/rupture time and stress/creep rate relation are known to occur during high-temperature creep. In the present work these deflections are explained in terms of different stress-dependences of the intracrystalline deformation rate and the rate of grain-boundary sliding. The transition from trans- to intercrystalline fracture, which coincides, at least approximately, with these breaks, is suggested to be due to the increased grain-boundary sliding at stresses below the break.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117035374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
AbstractReplicas have been examined both from the fracture surfaces and from polished sections of creep specimens of pure iron and copper, to determine the shape of grain-boundary cavities. From the observations a mechanism is proposed whereby combined grain-boundary sliding and grain deformation gives rise to cavity growth.
{"title":"Strain-Induced Cavity Development during Creep","authors":"P. W. Davies, K. R. Williams","doi":"10.1179/MSC.1969.3.1.48","DOIUrl":"https://doi.org/10.1179/MSC.1969.3.1.48","url":null,"abstract":"AbstractReplicas have been examined both from the fracture surfaces and from polished sections of creep specimens of pure iron and copper, to determine the shape of grain-boundary cavities. From the observations a mechanism is proposed whereby combined grain-boundary sliding and grain deformation gives rise to cavity growth.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114693620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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