Pub Date : 1984-11-01DOI: 10.1179/030634584790419755
C. Lea, M. Seah
Abstract In situ Auger electron spectroscopy measurements of the time and temperature dependence of phosphorus and tin segregation in a 5Ni-Cr-Mo-V (wt-%) rotor steel are presented and analysed in terms of the theory presented earlier by Lea and Seah. The complete C curve, constant segregation contours on the time–temperature diagram are analysed in terms of the diffusion, segregation, and evaporation parameters involved. It is shown that an inversion of the measured C curve occurs if the magnitude of the activation energy for evaporation is lower than that for diffusion. Phosphorus in iron is an example of this case, whereas for tin the reverse is true. Additionally, it is shown that the kinetics for surface segregation may be much faster than for grain boundary segregation if the latter provides a source of material to feed the former.
{"title":"Time and temperature dependence of surface segregation in commercial steel, studied by Auger electron spectroscopy","authors":"C. Lea, M. Seah","doi":"10.1179/030634584790419755","DOIUrl":"https://doi.org/10.1179/030634584790419755","url":null,"abstract":"Abstract In situ Auger electron spectroscopy measurements of the time and temperature dependence of phosphorus and tin segregation in a 5Ni-Cr-Mo-V (wt-%) rotor steel are presented and analysed in terms of the theory presented earlier by Lea and Seah. The complete C curve, constant segregation contours on the time–temperature diagram are analysed in terms of the diffusion, segregation, and evaporation parameters involved. It is shown that an inversion of the measured C curve occurs if the magnitude of the activation energy for evaporation is lower than that for diffusion. Phosphorus in iron is an example of this case, whereas for tin the reverse is true. Additionally, it is shown that the kinetics for surface segregation may be much faster than for grain boundary segregation if the latter provides a source of material to feed the former.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"129 1","pages":"521-526"},"PeriodicalIF":0.0,"publicationDate":"1984-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74588705","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 : 1984-11-01DOI: 10.1179/030634584790419746
E. Smith
AbstractThe paper considers the behaviour of (brittle) high strength materials for which the onset of crack extension and fracture instability are coincident in a fracture mechanics type test where the crack is sufficiently long that the plastic deformation, which is associated with the onset of crack extension, is highly localized to the vicinity of the crack tip. A theoretical analysis shows that both the J integral at the onset of crack extension and the effective fracture toughness decrease below their long crack values as the pre-existing crack size decreases. However, the predicted decreases are only small (≲515%) as the pre-existing crack size decreases to a level at which the applied stress approaches the tensile yield stress of the material. The theoretical predictions are consistent with the experimental results obtained by Wilshire and Knott.
{"title":"Effect of crack size on fracture of high yield stress materials","authors":"E. Smith","doi":"10.1179/030634584790419746","DOIUrl":"https://doi.org/10.1179/030634584790419746","url":null,"abstract":"AbstractThe paper considers the behaviour of (brittle) high strength materials for which the onset of crack extension and fracture instability are coincident in a fracture mechanics type test where the crack is sufficiently long that the plastic deformation, which is associated with the onset of crack extension, is highly localized to the vicinity of the crack tip. A theoretical analysis shows that both the J integral at the onset of crack extension and the effective fracture toughness decrease below their long crack values as the pre-existing crack size decreases. However, the predicted decreases are only small (≲515%) as the pre-existing crack size decreases to a level at which the applied stress approaches the tensile yield stress of the material. The theoretical predictions are consistent with the experimental results obtained by Wilshire and Knott.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"1 1","pages":"511-514"},"PeriodicalIF":0.0,"publicationDate":"1984-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89619561","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 : 1984-11-01DOI: 10.1179/030634584790419737
H. Ledbetter, M. Austin
AbstractFor the high nickel content austenitic stainless steel Fe-20Cr-16Ni-6Mn (wt-%), the complete set of polycrystalline elastic constants between 295 and 4 K were determined ultrasonically. A reversible magnetic transition occurs near 54 K. During cooling, the bulk modulus begins to soften at a much higher temperature, near 150 K. Local moments above the transition temperature may explain this peculiarity.
{"title":"Anomalous low temperature elastic-constant behaviour of Fe-20Cr-16Ni-6Mn","authors":"H. Ledbetter, M. Austin","doi":"10.1179/030634584790419737","DOIUrl":"https://doi.org/10.1179/030634584790419737","url":null,"abstract":"AbstractFor the high nickel content austenitic stainless steel Fe-20Cr-16Ni-6Mn (wt-%), the complete set of polycrystalline elastic constants between 295 and 4 K were determined ultrasonically. A reversible magnetic transition occurs near 54 K. During cooling, the bulk modulus begins to soften at a much higher temperature, near 150 K. Local moments above the transition temperature may explain this peculiarity.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"336 1","pages":"539-542"},"PeriodicalIF":0.0,"publicationDate":"1984-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79735471","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 : 1984-11-01DOI: 10.1179/030634584790419719
H. Raven, E. Nes
AbstractThe development of microstructure in α iron and steels during cold rolling has been investigated in the strain range e = 0.5–4.5. In the low strain region (e > 1.5), primary and secondary microbands were identified. The substructure development with strain has been explained in terms of a model in which the volume fraction of micro bands increases with increasing strain at the expense of a uniform cell structure matrix. At large strains, no ‘crystallographic’ microbands were detected, and it is suggested that in this region, slip is controlled by more short range events. The effect of initial grain size on strain hardening has been considered by comparing the behaviour of a coarse grained iron, a medium grain size low carbon steel, and an ultrafine grained high strength low alloy steel. The observations suggest that during cold rolling the flow mechanism will change from being substructure controlled (σ = σ0 + kd−1, where d is the subboundary separation) to grain boundary controlled (σ = σ0 + kd−½...
{"title":"Structure and properties of heavily cold rolled iron and high strength low alloy and low carbon steels","authors":"H. Raven, E. Nes","doi":"10.1179/030634584790419719","DOIUrl":"https://doi.org/10.1179/030634584790419719","url":null,"abstract":"AbstractThe development of microstructure in α iron and steels during cold rolling has been investigated in the strain range e = 0.5–4.5. In the low strain region (e > 1.5), primary and secondary microbands were identified. The substructure development with strain has been explained in terms of a model in which the volume fraction of micro bands increases with increasing strain at the expense of a uniform cell structure matrix. At large strains, no ‘crystallographic’ microbands were detected, and it is suggested that in this region, slip is controlled by more short range events. The effect of initial grain size on strain hardening has been considered by comparing the behaviour of a coarse grained iron, a medium grain size low carbon steel, and an ultrafine grained high strength low alloy steel. The observations suggest that during cold rolling the flow mechanism will change from being substructure controlled (σ = σ0 + kd−1, where d is the subboundary separation) to grain boundary controlled (σ = σ0 + kd−½...","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"186 1","pages":"515-520"},"PeriodicalIF":0.0,"publicationDate":"1984-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77075175","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 : 1984-11-01DOI: 10.1179/030634584790419692
T. Öztürk, G. J. Davies
Abstract An analysis was carried out into the occurrence of grain-to-grain strain inhomogeneity in plane strain deformation of cubic metals. In the analysis, homogeneous strain constituted the reference state, and the inhomogeneity was introduced through shear deformations which were allowed to occur simultaneously with plane strain in individual grains. Each of the three possible shear deformations was considered, and grain orientations at which these additional shears are favoured were determined. An evaluation is then carried out of the role of this grain-to-grain shear inhomogeneity in the texture development of rolled cubic metals.
{"title":"Grain-to-grain strain inhomogeneity and development of rolling textures in cubic metals","authors":"T. Öztürk, G. J. Davies","doi":"10.1179/030634584790419692","DOIUrl":"https://doi.org/10.1179/030634584790419692","url":null,"abstract":"Abstract An analysis was carried out into the occurrence of grain-to-grain strain inhomogeneity in plane strain deformation of cubic metals. In the analysis, homogeneous strain constituted the reference state, and the inhomogeneity was introduced through shear deformations which were allowed to occur simultaneously with plane strain in individual grains. Each of the three possible shear deformations was considered, and grain orientations at which these additional shears are favoured were determined. An evaluation is then carried out of the role of this grain-to-grain shear inhomogeneity in the texture development of rolled cubic metals.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"76 1","pages":"531-538"},"PeriodicalIF":0.0,"publicationDate":"1984-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77050111","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 : 1984-10-01DOI: 10.1179/030634584790253119
D. Kelly, P. Niessen
AbstractStrain softening in a wrought Pb–Ca–Sn battery alloy is explained by the formation of shear bands during subsequent deformation. It is shown that these bands develop as a result of geometric softening, but once they exist the localized deformation in these bands causes shearing and subsequent dissolution of precipitates producing a substantial loss of strength. Adiabatic heating in the shear bands promotes localized dissolution of precipitates and recrystallization. As the reduction in rolling is increased the number of shear bands increases while their strength decreases. This leads to a decrease in maximum tensile strength and an increase in elongation to fracture.
{"title":"Strain softening behaviour of Pb–0.064Ca–0.44Sn wrought sheet","authors":"D. Kelly, P. Niessen","doi":"10.1179/030634584790253119","DOIUrl":"https://doi.org/10.1179/030634584790253119","url":null,"abstract":"AbstractStrain softening in a wrought Pb–Ca–Sn battery alloy is explained by the formation of shear bands during subsequent deformation. It is shown that these bands develop as a result of geometric softening, but once they exist the localized deformation in these bands causes shearing and subsequent dissolution of precipitates producing a substantial loss of strength. Adiabatic heating in the shear bands promotes localized dissolution of precipitates and recrystallization. As the reduction in rolling is increased the number of shear bands increases while their strength decreases. This leads to a decrease in maximum tensile strength and an increase in elongation to fracture.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"99 1","pages":"467-470"},"PeriodicalIF":0.0,"publicationDate":"1984-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79302732","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 : 1984-10-01DOI: 10.1179/030634584790253155
E. A. Wilson
AbstractEvidence is presented to show that five transformation products are possible in pure iron and dilute substitutional alloys: equiaxed ferrite, massive ferrite, bainitic ferrite, lath martensite (massive martensite), and twinned martensite. The morphology and transformation temperatures of these products are discussed. In conclusion, the chemical driving force for each of the transformations is calculated as a function of composition.
{"title":"γ → α transformation in Fe, Fe–Ni, and Fe–Cr alloys","authors":"E. A. Wilson","doi":"10.1179/030634584790253155","DOIUrl":"https://doi.org/10.1179/030634584790253155","url":null,"abstract":"AbstractEvidence is presented to show that five transformation products are possible in pure iron and dilute substitutional alloys: equiaxed ferrite, massive ferrite, bainitic ferrite, lath martensite (massive martensite), and twinned martensite. The morphology and transformation temperatures of these products are discussed. In conclusion, the chemical driving force for each of the transformations is calculated as a function of composition.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"10 1","pages":"471-484"},"PeriodicalIF":0.0,"publicationDate":"1984-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84608869","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 : 1984-10-01DOI: 10.1179/030634584790253146
A. Halstead, R. Rawlings
AbstractThe effects of cooling rate during solidification and of subsequent heat treatment on the microstructure and hardness of two cobalt base Co–Mo–Cr–Si alloys have been investigated. It had been thought that the solid solution constituent of these alloys in the cast condition had the fcc crystal structure, but both the fcc and hcp forms were found with the hcp phase being dominant. The amount of hcp fell at the fastest cooling rate studied, but the microstructure was generally relatively insensitive to cooling rate. The as-cast alloys could be softened or hardened by subsequent heat treatment and these hardness changes are discussed in terms of the fcc ⇌ hcp allotropic transformation and a precipitation reaction.
{"title":"Structure and hardness of Co-Mo-Cr-Si wear resistant alloys (Tribaloys)","authors":"A. Halstead, R. Rawlings","doi":"10.1179/030634584790253146","DOIUrl":"https://doi.org/10.1179/030634584790253146","url":null,"abstract":"AbstractThe effects of cooling rate during solidification and of subsequent heat treatment on the microstructure and hardness of two cobalt base Co–Mo–Cr–Si alloys have been investigated. It had been thought that the solid solution constituent of these alloys in the cast condition had the fcc crystal structure, but both the fcc and hcp forms were found with the hcp phase being dominant. The amount of hcp fell at the fastest cooling rate studied, but the microstructure was generally relatively insensitive to cooling rate. The as-cast alloys could be softened or hardened by subsequent heat treatment and these hardness changes are discussed in terms of the fcc ⇌ hcp allotropic transformation and a precipitation reaction.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"121 2 1","pages":"491-500"},"PeriodicalIF":0.0,"publicationDate":"1984-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87984607","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 : 1984-10-01DOI: 10.1179/030634584790253128
D. Northwood, I. Smith
AbstractThe shape of the strain transient following a sudden stress change (drop or increment) during steady state creep has been investigated for AI, AI–Mg alloys, AI–Li alloys, Cu, and Zr−1 wt-%Nb over a range of temperatures. The strain transients were classified as N type, for which the initial creep rate is high but decreases with time eventually reaching a constant value, or I type, for which the creep rate gradually increases to a constant value. The shape after a stress increment can be used as a guide to the rate controlling process of creep with pure metals and Class 2 alloys in which recovery is rate controlling showing an N type transient, and Class 1 alloys in which viscous glide is rate controlling showing I type transients. The shape of the strain transient after a sudden stress drop gives no clear indication of the rate controlling mechanism since, in general, pure metals and Class 1 and Class 2 alloys each show I type transients.
{"title":"Shape of transient creep curves following stress change during steady state creep","authors":"D. Northwood, I. Smith","doi":"10.1179/030634584790253128","DOIUrl":"https://doi.org/10.1179/030634584790253128","url":null,"abstract":"AbstractThe shape of the strain transient following a sudden stress change (drop or increment) during steady state creep has been investigated for AI, AI–Mg alloys, AI–Li alloys, Cu, and Zr−1 wt-%Nb over a range of temperatures. The strain transients were classified as N type, for which the initial creep rate is high but decreases with time eventually reaching a constant value, or I type, for which the creep rate gradually increases to a constant value. The shape after a stress increment can be used as a guide to the rate controlling process of creep with pure metals and Class 2 alloys in which recovery is rate controlling showing an N type transient, and Class 1 alloys in which viscous glide is rate controlling showing I type transients. The shape of the strain transient after a sudden stress drop gives no clear indication of the rate controlling mechanism since, in general, pure metals and Class 1 and Class 2 alloys each show I type transients.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"144 1","pages":"485-490"},"PeriodicalIF":0.0,"publicationDate":"1984-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89064972","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 : 1984-10-01DOI: 10.1179/030634584790253137
J. Andersson, P. Gustafson, M. Hillert, B. Jansson, B. Sundman, J. Ågren
AbstractThe phase diagrams and thermodynamic properties of many alloy systems have been assessed in recent years and much of this information is now available in databanks, some of which are accessible online. This new facility may be of considerable value to metallurgical research and the present communication describes an example.
{"title":"Ferrite–austenite equilibrium in silicon steels","authors":"J. Andersson, P. Gustafson, M. Hillert, B. Jansson, B. Sundman, J. Ågren","doi":"10.1179/030634584790253137","DOIUrl":"https://doi.org/10.1179/030634584790253137","url":null,"abstract":"AbstractThe phase diagrams and thermodynamic properties of many alloy systems have been assessed in recent years and much of this information is now available in databanks, some of which are accessible online. This new facility may be of considerable value to metallurgical research and the present communication describes an example.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"41 23 1","pages":"501-502"},"PeriodicalIF":0.0,"publicationDate":"1984-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89266576","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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