Pub Date : 1900-01-01DOI: 10.1179/030634570790444185
T. Watanabe, S. Karashima
AbstractStress-relaxation and tensile tests have been performed at various creep strains to study the dynamic-recovery and work-hardening behaviour of alpha-iron during creep. The work-hardening rate controls the creep deformation to a minor extent only; the observed creep rates at various stresses and temperatures can be explained mainly in terms of the dynamic-recovery rates in both the paramagnetic and the ferromagnetic temperature regions. The activation energies for dynamic recovery are in good agreement with those for creep, which are equal to the activation energies for self-diffusion. Thus, it is concluded that the creep deformation of alpha-iron is determined by a diffusion-controlled dynamic-recovery process. It is also proposed that the stress-relaxation method should be used in quantitative studies of dynamic recovery during creep.
{"title":"An Interpretation of Creep Deformation in Alpha-Iron from the Viewpoint of Dynamic Recovery","authors":"T. Watanabe, S. Karashima","doi":"10.1179/030634570790444185","DOIUrl":"https://doi.org/10.1179/030634570790444185","url":null,"abstract":"AbstractStress-relaxation and tensile tests have been performed at various creep strains to study the dynamic-recovery and work-hardening behaviour of alpha-iron during creep. The work-hardening rate controls the creep deformation to a minor extent only; the observed creep rates at various stresses and temperatures can be explained mainly in terms of the dynamic-recovery rates in both the paramagnetic and the ferromagnetic temperature regions. The activation energies for dynamic recovery are in good agreement with those for creep, which are equal to the activation energies for self-diffusion. Thus, it is concluded that the creep deformation of alpha-iron is determined by a diffusion-controlled dynamic-recovery process. It is also proposed that the stress-relaxation method should be used in quantitative studies of dynamic recovery during creep.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"9 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":"132404240","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.1967.1.1.152
C. L. Formby
AbstractMeasurements of the differences between the minimum crack lengths to cause failure for stationary and fast-running cracks are described. The experiments were performed at room temperature on quenched and tempered steels having a range of ductilities. The results are explained in terms of the variation of effective surface energy with strain rate and the influence of plate thickness. An estimate is made of the effect of kinetic energy in reducing the critical running-crack length.
{"title":"Conditions for Arrest of a Running Crack in Quenched and Tempered Steels","authors":"C. L. Formby","doi":"10.1179/MSC.1967.1.1.152","DOIUrl":"https://doi.org/10.1179/MSC.1967.1.1.152","url":null,"abstract":"AbstractMeasurements of the differences between the minimum crack lengths to cause failure for stationary and fast-running cracks are described. The experiments were performed at room temperature on quenched and tempered steels having a range of ductilities. The results are explained in terms of the variation of effective surface energy with strain rate and the influence of plate thickness. An estimate is made of the effect of kinetic energy in reducing the critical running-crack length.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"38 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132694522","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.1970.4.1.219
N. Ridley, H. Stuart
AbstractThe lattice parameters of a number of iron–carbon alloys have been measured in the austenite field for temperatures up to 1200° C (1473 K). By extrapolation and interpolation of these data the variation with carbon concentration of the lattice parameter of austenite has been determined for a wide range of temperatures, and used to calculate partial molar volumes of iron and carbon in austenite. Both partial molar quantities show little variation with composition but V c, γ decreases with increasing temperature, while V Fe, γ increases. The values obtained for the partial molar volume of carbon in austenite are appreciably lower than those cited earlier. It is probable that the differences previously reported between the measured and calculated effect of pressure on the composition of austenite in equilibrium with cementite at 727° C (1000 K), are due primarily to the use in the calculations of too high a value for the partial molar volume of carbon in austenite.
{"title":"Partial Molar Volumes from High-Temperature Lattice Parameters of Iron–Carbon Austenites","authors":"N. Ridley, H. Stuart","doi":"10.1179/MSC.1970.4.1.219","DOIUrl":"https://doi.org/10.1179/MSC.1970.4.1.219","url":null,"abstract":"AbstractThe lattice parameters of a number of iron–carbon alloys have been measured in the austenite field for temperatures up to 1200° C (1473 K). By extrapolation and interpolation of these data the variation with carbon concentration of the lattice parameter of austenite has been determined for a wide range of temperatures, and used to calculate partial molar volumes of iron and carbon in austenite. Both partial molar quantities show little variation with composition but V c, γ decreases with increasing temperature, while V Fe, γ increases. The values obtained for the partial molar volume of carbon in austenite are appreciably lower than those cited earlier. It is probable that the differences previously reported between the measured and calculated effect of pressure on the composition of austenite in equilibrium with cementite at 727° C (1000 K), are due primarily to the use in the calculations of too high a value for the partial molar volume of carbon in austenite.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"8 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":"133190090","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: 10.1179/030634568790443332
A. Gittins
AbstractDuring the fatigue of copper at elevated temperatures cavities form on grain boundaries and cause a decrease in density. The fractional change in density is directly proportional to time for tests in which the plastic strain amplitude remains constant. In constant-stress tests, when the stress is sufficient to cause appreciable hardening, the fractional change in density is approximately proportional to (time)⅔. For the majority of the tests the activation energy of the growth process is 24.2 kcal.mole−1; this and other evidence suggests that growth depends on a grain-boundary diffusion mechanism as well as on the migration of vacancies created by fatigue. The results are interpreted on the basis of a model in which defects absorbed by grain-boundary migration contribute to cavity growth.
{"title":"The Mechanism of Cavity Growth in Copper during High-Temperature Fatigue","authors":"A. Gittins","doi":"10.1179/030634568790443332","DOIUrl":"https://doi.org/10.1179/030634568790443332","url":null,"abstract":"AbstractDuring the fatigue of copper at elevated temperatures cavities form on grain boundaries and cause a decrease in density. The fractional change in density is directly proportional to time for tests in which the plastic strain amplitude remains constant. In constant-stress tests, when the stress is sufficient to cause appreciable hardening, the fractional change in density is approximately proportional to (time)⅔. For the majority of the tests the activation energy of the growth process is 24.2 kcal.mole−1; this and other evidence suggests that growth depends on a grain-boundary diffusion mechanism as well as on the migration of vacancies created by fatigue. The results are interpreted on the basis of a model in which defects absorbed by grain-boundary migration contribute to cavity growth.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"22 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":"131423720","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: 10.1179/030634568790443125
B. Banerjee, J. Hauser, J. Capenos
Abstract The new maraging alloys, which possess some of the highest strength and toughness combinations available in commercial alloys, are based on the iron-nickel martensites, further strengthened by precipitation reactions involving molybdenum, titanium, and aluminium. But enough (∼ 8%) cobalt is also needed to develop the desired properties, even though cobalt itself is absent in the precipitate phases. To determine the role of cobalt in these alloys, an iron-18 % Ni binary, a 4% Mo ternary, an 8% Co ternary, and a 4% Mo-8% Co quaternary alloy have been studied by transmission electron microscopy. The effect of cobalt on matrix strengthening was found to be based on cobalt lowering the stacking-fault energy (SFE) of the matrix. The lowered SFE discourages cross-slip and retards cell growth. The resulting increase in average dislocation density provides more nucleation sites for the precipitates, which stabilize the dislocation forest and increase interference for moving dislocations; thus strength is ...
{"title":"Role of Cobalt in the Marage-Type Alloy Matrix","authors":"B. Banerjee, J. Hauser, J. Capenos","doi":"10.1179/030634568790443125","DOIUrl":"https://doi.org/10.1179/030634568790443125","url":null,"abstract":"Abstract The new maraging alloys, which possess some of the highest strength and toughness combinations available in commercial alloys, are based on the iron-nickel martensites, further strengthened by precipitation reactions involving molybdenum, titanium, and aluminium. But enough (∼ 8%) cobalt is also needed to develop the desired properties, even though cobalt itself is absent in the precipitate phases. To determine the role of cobalt in these alloys, an iron-18 % Ni binary, a 4% Mo ternary, an 8% Co ternary, and a 4% Mo-8% Co quaternary alloy have been studied by transmission electron microscopy. The effect of cobalt on matrix strengthening was found to be based on cobalt lowering the stacking-fault energy (SFE) of the matrix. The lowered SFE discourages cross-slip and retards cell growth. The resulting increase in average dislocation density provides more nucleation sites for the precipitates, which stabilize the dislocation forest and increase interference for moving dislocations; thus strength is ...","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"310 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":"115942130","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: 10.1179/030634568790443206
J. Hedley
AbstractBy obtaining a clearer understanding of the mechanism of damping operating in manganese-copper alloys it may be possible either to improve damping properties at elevated temperatures or to select alternative systems with better ancillary properties. Electron-microscope, X-ray, and neutron-diffraction techniques have been used to identify those microstructural features thought to be responsible for the high damping capacity of manganese-copper. Only those compositions that are tetragonal have a high damping capacity. The tetragonality is induced by an antiferromagnetic ordering of manganese ions and the Neel temperature is associated with the drastic fall in damping capacity as the temperature is raised. The structural distortion caused by the cubic → tetragonal transformation creates microtwins and it is the nucleation and growth of these twins that is thought to give rise to the vibrational energy absorption.
{"title":"The Mechanism of Damping in Manganese-Copper Alloys","authors":"J. Hedley","doi":"10.1179/030634568790443206","DOIUrl":"https://doi.org/10.1179/030634568790443206","url":null,"abstract":"AbstractBy obtaining a clearer understanding of the mechanism of damping operating in manganese-copper alloys it may be possible either to improve damping properties at elevated temperatures or to select alternative systems with better ancillary properties. Electron-microscope, X-ray, and neutron-diffraction techniques have been used to identify those microstructural features thought to be responsible for the high damping capacity of manganese-copper. Only those compositions that are tetragonal have a high damping capacity. The tetragonality is induced by an antiferromagnetic ordering of manganese ions and the Neel temperature is associated with the drastic fall in damping capacity as the temperature is raised. The structural distortion caused by the cubic → tetragonal transformation creates microtwins and it is the nucleation and growth of these twins that is thought to give rise to the vibrational energy absorption.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"161 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":"114730945","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: 10.1179/030634568790443107
J. Myers, G. Willoughby, R. Ham
AbstractCreep tests have been carried out on the three principal transformation structures of a Cr-Mo-V rotor steel which had been given a common tempering treatment. Although creep strength varied with transformation structure, being lowest for martensite and highest for bainite, a single form of σ-έ-T relationship was obtained which can be derived from a solute-drag model.
{"title":"The Creep Behaviour of a 1% Cr-Mo-V Rotor Steel","authors":"J. Myers, G. Willoughby, R. Ham","doi":"10.1179/030634568790443107","DOIUrl":"https://doi.org/10.1179/030634568790443107","url":null,"abstract":"AbstractCreep tests have been carried out on the three principal transformation structures of a Cr-Mo-V rotor steel which had been given a common tempering treatment. Although creep strength varied with transformation structure, being lowest for martensite and highest for bainite, a single form of σ-έ-T relationship was obtained which can be derived from a solute-drag model.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"22 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":"117010397","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.1967.1.1.186
M. M. Hutchison, R. Honeycombe
AbstractThe stacking-fault energies of stable silver-gallium solid solutions decrease linearly with increased solute concentration and the strain required to form a cell structure increases linearly. Tetrahedral stacking-fault defects, produced during deformation, were studied in the 2% Ga alloy. A transition was noted in the distribution, the rate of production, and the maximum size of these tetrahedra at the strain at which a cell structure was first observed. However, there was no correlation between this strain and the stress vs. strain curves of the alloys.
{"title":"The Electron Microstructure of Deformed Silver and Silver-Gallium Alloys","authors":"M. M. Hutchison, R. Honeycombe","doi":"10.1179/MSC.1967.1.1.186","DOIUrl":"https://doi.org/10.1179/MSC.1967.1.1.186","url":null,"abstract":"AbstractThe stacking-fault energies of stable silver-gallium solid solutions decrease linearly with increased solute concentration and the strain required to form a cell structure increases linearly. Tetrahedral stacking-fault defects, produced during deformation, were studied in the 2% Ga alloy. A transition was noted in the distribution, the rate of production, and the maximum size of these tetrahedra at the strain at which a cell structure was first observed. However, there was no correlation between this strain and the stress vs. strain curves of the alloys.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"43 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":"117310097","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: 10.1179/030634570790444248
S. Floreen, H. W. Hayden
Abstract A high-carbon maraging steel has been subjected to four different heat-treatments to vary its tensile properties. The stresses necessary to initiate cracking of TiC particles in the steel were then determined. In all cases cracking began at about the point when visible necking occurred in the tensile specimens. The results are discussed in terms of the influence of the maraging precipitate particles in homogenizing flow and changing the local stresses at the carbide particles. The results show that suitable precipitate dispersions can both significantly increase the strength and minimize cracking of brittle inclusion particles.
{"title":"Carbide Cracking in a High-Strength Steel","authors":"S. Floreen, H. W. Hayden","doi":"10.1179/030634570790444248","DOIUrl":"https://doi.org/10.1179/030634570790444248","url":null,"abstract":"Abstract A high-carbon maraging steel has been subjected to four different heat-treatments to vary its tensile properties. The stresses necessary to initiate cracking of TiC particles in the steel were then determined. In all cases cracking began at about the point when visible necking occurred in the tensile specimens. The results are discussed in terms of the influence of the maraging precipitate particles in homogenizing flow and changing the local stresses at the carbide particles. The results show that suitable precipitate dispersions can both significantly increase the strength and minimize cracking of brittle inclusion particles.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"65 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":"116355645","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}
AbstractThe absolute surface energy of pure δ-iron as a function of nitrogen content within the solidsolubility range has been measured. The surface energy is significantly reduced, showing that nitrogen is surface-active. The temperature-dependence of the surface energy of Fe-0.01 % N is positive and equal to 1.1 erg/cm2/degC. At saturation coverage of the surface, there is 0.7 ± 0.2 atom of nitrogen per surface atom of iron, with an estimated mean binding energy of 53 ± 5 kcal/mole. The binding energy of nitrogen to grain boundaries is 21 ± 3 kcal/mole. The results are discussed with reference to the contribution of grain boundaries to the total nitrogen solubility in iron and the relevance of grain-boundary adsorption to the intergranular fracture strength.
{"title":"Interfacial Segregation of Nitrogen in Iron","authors":"E. D. Hondros","doi":"10.1179/MSC.1967.1.1.36","DOIUrl":"https://doi.org/10.1179/MSC.1967.1.1.36","url":null,"abstract":"AbstractThe absolute surface energy of pure δ-iron as a function of nitrogen content within the solidsolubility range has been measured. The surface energy is significantly reduced, showing that nitrogen is surface-active. The temperature-dependence of the surface energy of Fe-0.01 % N is positive and equal to 1.1 erg/cm2/degC. At saturation coverage of the surface, there is 0.7 ± 0.2 atom of nitrogen per surface atom of iron, with an estimated mean binding energy of 53 ± 5 kcal/mole. The binding energy of nitrogen to grain boundaries is 21 ± 3 kcal/mole. The results are discussed with reference to the contribution of grain boundaries to the total nitrogen solubility in iron and the relevance of grain-boundary adsorption to the intergranular fracture strength.","PeriodicalId":103313,"journal":{"name":"Metal Science Journal","volume":"14 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":"116413884","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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