Pub Date : 1984-02-01DOI: 10.1179/030634584790420221
R. Ricks
AbstractThis paper presents a detailed investigation of a complex cellular transformation in an Fe-25Ni-20Cr-2Al-2Ti alloy. Convergent beam electron diffraction and energy dispersive X-ray spectroscopy are used to monitor the reaction, including the precipitation on existing grain boundaries which precedes the cellular transformation. It is shown that growth of this cellular precipitation involves the volume diffusion of solute such that the growth rate decreases with aging time. The consequences of this decrease of reaction rate are discussed with particular reference to the types of cellular transformation product formed.
{"title":"Cellular precipitation in austenitic stainless steel containing aluminium and titanium","authors":"R. Ricks","doi":"10.1179/030634584790420221","DOIUrl":"https://doi.org/10.1179/030634584790420221","url":null,"abstract":"AbstractThis paper presents a detailed investigation of a complex cellular transformation in an Fe-25Ni-20Cr-2Al-2Ti alloy. Convergent beam electron diffraction and energy dispersive X-ray spectroscopy are used to monitor the reaction, including the precipitation on existing grain boundaries which precedes the cellular transformation. It is shown that growth of this cellular precipitation involves the volume diffusion of solute such that the growth rate decreases with aging time. The consequences of this decrease of reaction rate are discussed with particular reference to the types of cellular transformation product formed.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"39 1","pages":"49-56"},"PeriodicalIF":0.0,"publicationDate":"1984-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87598409","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 : 1984-02-01DOI: 10.1179/030634584790420258
T. Haratani, W. Hutchinson, I. Dillamore, P. Bate
AbstractA number of experiments involving cold rolling and annealing have been carried out on polycrystalline and single crystal silicon iron. It is shown that the microstructural state just beneath the surface of the sheet before cold rolling is an important factor in the successful development of Goss texture during simulated processing. A coarse grained surface zone encourages formation of shear bands during rolling and these become preferential sites for nucleation during primary recrystallization. Nucleation of secondary grains, which also occurs just beneath the sheet surface, appears to be dependent on the prior existence of the shear band structure. Single crystals with the orientation (111)[112] are prone to shear banding during cold rolling especially when strain aging conditions are established. During subsequent annealing the shear bands recrystallize first, producing new grains which have the Goss orientation. The texture after complete recrystallization is the same as that of the shear band ...
{"title":"Contribution of shear banding to origin of Goss texture in silicon iron","authors":"T. Haratani, W. Hutchinson, I. Dillamore, P. Bate","doi":"10.1179/030634584790420258","DOIUrl":"https://doi.org/10.1179/030634584790420258","url":null,"abstract":"AbstractA number of experiments involving cold rolling and annealing have been carried out on polycrystalline and single crystal silicon iron. It is shown that the microstructural state just beneath the surface of the sheet before cold rolling is an important factor in the successful development of Goss texture during simulated processing. A coarse grained surface zone encourages formation of shear bands during rolling and these become preferential sites for nucleation during primary recrystallization. Nucleation of secondary grains, which also occurs just beneath the sheet surface, appears to be dependent on the prior existence of the shear band structure. Single crystals with the orientation (111)[112] are prone to shear banding during cold rolling especially when strain aging conditions are established. During subsequent annealing the shear bands recrystallize first, producing new grains which have the Goss orientation. The texture after complete recrystallization is the same as that of the shear band ...","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"65 1","pages":"57-65"},"PeriodicalIF":0.0,"publicationDate":"1984-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78690596","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 : 1984-02-01DOI: 10.1179/030634584790420276
D. Curry
AbstractTests have been performed to examine the yield stress and the cleavage fracture stress at −196°C of SA 508 Class 2 pressure vessel steel in a range of heat treatment conditions. The heat treatments either varied the austenitization temperature before isothermal transformation at 450°C or varied the tempering treatment after austenitizing at 900°C and transforming at 450°C. The resultant microstructures have been characterized by metallographic and fractographic examination. Austenitization at temperatures below about 1000°C produced a polygonal ferritic structure, whereas an upper bainite was produced following austenitization above this temperature. Increasing the austenitizing temperature caused first the ferrite grain size and then the bainitic packet size to increase. However, the lath width of the bainitic microstructures decreased, which is consistent with an increase in hardenability accompanying the increased prior austenite grain size. Tempering caused the precipitation of rodlike carbide...
{"title":"Influence of microstructure on yield stress and cleavage fracture stress at −196°C of SA 508 Class 2 pressure vessel steel","authors":"D. Curry","doi":"10.1179/030634584790420276","DOIUrl":"https://doi.org/10.1179/030634584790420276","url":null,"abstract":"AbstractTests have been performed to examine the yield stress and the cleavage fracture stress at −196°C of SA 508 Class 2 pressure vessel steel in a range of heat treatment conditions. The heat treatments either varied the austenitization temperature before isothermal transformation at 450°C or varied the tempering treatment after austenitizing at 900°C and transforming at 450°C. The resultant microstructures have been characterized by metallographic and fractographic examination. Austenitization at temperatures below about 1000°C produced a polygonal ferritic structure, whereas an upper bainite was produced following austenitization above this temperature. Increasing the austenitizing temperature caused first the ferrite grain size and then the bainitic packet size to increase. However, the lath width of the bainitic microstructures decreased, which is consistent with an increase in hardenability accompanying the increased prior austenite grain size. Tempering caused the precipitation of rodlike carbide...","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"11 1","pages":"67-76"},"PeriodicalIF":0.0,"publicationDate":"1984-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84089916","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 : 1984-02-01DOI: 10.1179/030634584790420249
I. Weiss, T. Sakai, J. Jonas
Abstract The effect of test method on the transition from multiple to single peak dynamic recrystallization is reviewed. Data obtained from tension, compression, and torsion tests are used to evaluate the dependence of the peak and recrystallization strains on the peak stress. It is shown that the intersection stress at which the peak and recrystallization strains are equal depends on the type of test employed. Thus, it does not conform to the critical transition stress which distinguishes between grain refinement (and single peak flow) on the one hand, and grain coarsening (and multiple peak flow) on the other. The discrepancy arises because factors such as flow localization, stress gradients, friction, and the difficulty of determining the surface shear stress from torque data all affect the peak and recrystallization strains, thus modifying the intersection stress.
{"title":"Effect of test method on transition from multiple to single peak dynamic recrystallization","authors":"I. Weiss, T. Sakai, J. Jonas","doi":"10.1179/030634584790420249","DOIUrl":"https://doi.org/10.1179/030634584790420249","url":null,"abstract":"Abstract The effect of test method on the transition from multiple to single peak dynamic recrystallization is reviewed. Data obtained from tension, compression, and torsion tests are used to evaluate the dependence of the peak and recrystallization strains on the peak stress. It is shown that the intersection stress at which the peak and recrystallization strains are equal depends on the type of test employed. Thus, it does not conform to the critical transition stress which distinguishes between grain refinement (and single peak flow) on the one hand, and grain coarsening (and multiple peak flow) on the other. The discrepancy arises because factors such as flow localization, stress gradients, friction, and the difficulty of determining the surface shear stress from torque data all affect the peak and recrystallization strains, thus modifying the intersection stress.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"31 1","pages":"77-84"},"PeriodicalIF":0.0,"publicationDate":"1984-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89175556","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 : 1984-02-01DOI: 10.1179/030634584790420212
M. Blicharski
AbstractProcesses taking place in the course of annealing of deformed ferrite–austenite stainless steel have been examined by means of light and electron metallography. Deformations of 23, 43, and 85% were obtained by rolling at room temperature. It has been found that ferrite and austenite recrystallize discontinuously irrespective of the magnitude of the deformation. Ferrite recrystallization is preceded by extensive recovery processes. Initially this induces the formation of elongated subgrains, whose growth results in a rapid spheroidization and nucleation of recrystallization. The recovery of austenite before recrystallization is far more limited and, in general, does not lead to the formation of a subgrain structure. The preferred regions of recrystallization nuclei formation in ferrite are shear bands and microbands, whereas in austenite the nucleation of recrystallization takes place at the intersections of deformation twins and in shear bands. The size of ferrite and austenite grains after recrys...
{"title":"Recrystallization of ferrite–austenite stainless steel","authors":"M. Blicharski","doi":"10.1179/030634584790420212","DOIUrl":"https://doi.org/10.1179/030634584790420212","url":null,"abstract":"AbstractProcesses taking place in the course of annealing of deformed ferrite–austenite stainless steel have been examined by means of light and electron metallography. Deformations of 23, 43, and 85% were obtained by rolling at room temperature. It has been found that ferrite and austenite recrystallize discontinuously irrespective of the magnitude of the deformation. Ferrite recrystallization is preceded by extensive recovery processes. Initially this induces the formation of elongated subgrains, whose growth results in a rapid spheroidization and nucleation of recrystallization. The recovery of austenite before recrystallization is far more limited and, in general, does not lead to the formation of a subgrain structure. The preferred regions of recrystallization nuclei formation in ferrite are shear bands and microbands, whereas in austenite the nucleation of recrystallization takes place at the intersections of deformation twins and in shear bands. The size of ferrite and austenite grains after recrys...","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"17 1","pages":"99-102"},"PeriodicalIF":0.0,"publicationDate":"1984-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82980750","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 : 1984-02-01DOI: 10.1179/030634584790420267
M. Blicharski
AbstractThe examination covered two phase ferrite–austenite steel of coarse grained structure after 23, 43, and 85% deformation induced by rolling at room temperature. Optical and electron metallography have been used in the investigations and the formation of Neumann bands was revealed for reductions below 5%; for increased reductions the deformation of ferrite occurred by slip only. Ferrite deformation induces a rapid increase of dislocation density. In the dislocation structure, bands of increased dislocation density can be observed that are usually parallel to {110} planes and uni- or two directional in a given region. Increases in strain induce an increase of dislocation density as well as a decrease of the spacing between the bands. The formation of micro bands, microband clusters, and shear bands indicates ferrite non-homogeneous deformation. For low strains, austenite deformation occurs by slip only. In austenite, intensive twinning occurs for reductions between 20 and 40%, whereas for reductions ...
{"title":"Structure of deformed ferrite–austenite stainless steel","authors":"M. Blicharski","doi":"10.1179/030634584790420267","DOIUrl":"https://doi.org/10.1179/030634584790420267","url":null,"abstract":"AbstractThe examination covered two phase ferrite–austenite steel of coarse grained structure after 23, 43, and 85% deformation induced by rolling at room temperature. Optical and electron metallography have been used in the investigations and the formation of Neumann bands was revealed for reductions below 5%; for increased reductions the deformation of ferrite occurred by slip only. Ferrite deformation induces a rapid increase of dislocation density. In the dislocation structure, bands of increased dislocation density can be observed that are usually parallel to {110} planes and uni- or two directional in a given region. Increases in strain induce an increase of dislocation density as well as a decrease of the spacing between the bands. The formation of micro bands, microband clusters, and shear bands indicates ferrite non-homogeneous deformation. For low strains, austenite deformation occurs by slip only. In austenite, intensive twinning occurs for reductions between 20 and 40%, whereas for reductions ...","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"100 1","pages":"92-98"},"PeriodicalIF":0.0,"publicationDate":"1984-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80297094","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 : 1984-02-01DOI: 10.1179/030634584790420294
W. Beeré
AbstractThe theory of constant load uniaxial tests and constant pressure tube burst tests is compared with observed values of minimum creep rate e m and time to failure t f. It is shown that the product e m t f can exceed the asymptotic value 1/n (1/2n for tubes) at large failure strains, where n is the stress exponent for creep. A fracture model based on cavity growth mechanisms is developed for 20Cr-25Ni-Nb stainless steel. The predictions are compared with the observed values and related to the Monkman–Grant equation. It is shown that the constants in the latter equation incorporate the creep and failure mechanisms.
摘要将恒载单轴试验和恒压爆破试验理论与最小蠕变速率e m和失效时间t f的观测值进行了比较。结果表明，在大破坏应变下，其乘积e m t f可以超过渐近值1/n(对于钢管为1/2n)，其中n为蠕变应力指数。建立了基于空腔生长机制的20Cr-25Ni-Nb不锈钢断裂模型。将预测值与观测值进行比较，并与Monkman-Grant方程相关联。结果表明，后一方程中的常数包含蠕变和破坏机制。
{"title":"Fracture life for constant load creep tests and relationship with fracture mechanisms","authors":"W. Beeré","doi":"10.1179/030634584790420294","DOIUrl":"https://doi.org/10.1179/030634584790420294","url":null,"abstract":"AbstractThe theory of constant load uniaxial tests and constant pressure tube burst tests is compared with observed values of minimum creep rate e m and time to failure t f. It is shown that the product e m t f can exceed the asymptotic value 1/n (1/2n for tubes) at large failure strains, where n is the stress exponent for creep. A fracture model based on cavity growth mechanisms is developed for 20Cr-25Ni-Nb stainless steel. The predictions are compared with the observed values and related to the Monkman–Grant equation. It is shown that the constants in the latter equation incorporate the creep and failure mechanisms.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"42 1","pages":"85-91"},"PeriodicalIF":0.0,"publicationDate":"1984-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73284408","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 : 1984-02-01DOI: 10.1179/030634584790420230
K. Murakami, T. Okamoto
AbstractThe formation of the equiaxed zone was examined using a transparent succinonitrile–ethyl alcohol solution. The equiaxed crystals were found to be formed by detachment of dendrite arms owing to the convective flow of the bulk liquid. In the early stage of solidification, convection originates from the temperature differences in the liquid, and, in the later stage, from the floating up of alcohol enriched liquid. ejected from inverse V segregate channels in the mushy zone into the bulk liquid~When the superheat of a pouring solution is small, free crystal formation occurs in the liquid adjacent to the mould wall during and immediately after pouring.
{"title":"Formation of equiaxed zone in castings","authors":"K. Murakami, T. Okamoto","doi":"10.1179/030634584790420230","DOIUrl":"https://doi.org/10.1179/030634584790420230","url":null,"abstract":"AbstractThe formation of the equiaxed zone was examined using a transparent succinonitrile–ethyl alcohol solution. The equiaxed crystals were found to be formed by detachment of dendrite arms owing to the convective flow of the bulk liquid. In the early stage of solidification, convection originates from the temperature differences in the liquid, and, in the later stage, from the floating up of alcohol enriched liquid. ejected from inverse V segregate channels in the mushy zone into the bulk liquid~When the superheat of a pouring solution is small, free crystal formation occurs in the liquid adjacent to the mould wall during and immediately after pouring.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"16 1","pages":"103-111"},"PeriodicalIF":0.0,"publicationDate":"1984-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87237548","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 : 1984-01-01DOI: 10.1179/030634584790420320
N. Ridley, D. Burgess
AbstractPartitioning of cobalt between ferrite and cementite during the isothermal decomposition of austenite to pearlite has been studied for a 2.1 wt-%Co eutectoid steel using analytical electron microscopy of two stage extraction replicas. Cobalt partitioned preferentially to ferrite at the transformation front for temperatures down to 580°C. Although the extent of partitioning decreased as the reaction temperature was decreased, a no-partition temperature could not be identified experimentally for the alloy. However, calculations predicted that the no-partitioning temperature would be close to the eutectoid temperature. The inflexion in the plot of interlamellar spacing v. transformation temperature previously reported for the alloy is not inconsistent with the calculated no-partition temperature. For most of the pearlite transformation region the observed partitioning of Co could have accompanied the rate controlling step for pearlite growth which, for other than low undercoolings, would be carbon di...
{"title":"Partitioning of Co during pearlite growth in a eutectoid steel","authors":"N. Ridley, D. Burgess","doi":"10.1179/030634584790420320","DOIUrl":"https://doi.org/10.1179/030634584790420320","url":null,"abstract":"AbstractPartitioning of cobalt between ferrite and cementite during the isothermal decomposition of austenite to pearlite has been studied for a 2.1 wt-%Co eutectoid steel using analytical electron microscopy of two stage extraction replicas. Cobalt partitioned preferentially to ferrite at the transformation front for temperatures down to 580°C. Although the extent of partitioning decreased as the reaction temperature was decreased, a no-partition temperature could not be identified experimentally for the alloy. However, calculations predicted that the no-partitioning temperature would be close to the eutectoid temperature. The inflexion in the plot of interlamellar spacing v. transformation temperature previously reported for the alloy is not inconsistent with the calculated no-partition temperature. For most of the pearlite transformation region the observed partitioning of Co could have accompanied the rate controlling step for pearlite growth which, for other than low undercoolings, would be carbon di...","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"16 1","pages":"7-12"},"PeriodicalIF":0.0,"publicationDate":"1984-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86160436","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 : 1984-01-01DOI: 10.1179/030634584790420311
W. Pachla, L. Styczynski
AbstractThe effect of extrusion ratios in the range 60–100 on the structure and strength of cold hydrostatically extruded. copper of 99.9% purity are reviewed. The final structure is mainly formed as a result of dynamic and static recrystallization and is controlled directly by the temperature generated in the die and the cooling rate at the die exit. Because of the high thermal effect of the process (T/T m … 0.54), products air cooled are fully recrystallized, the process having no dependence on the value of extrusion ratio used but being a result of the high efficiency of postdynamic recrystallization and secondary grain growth. It is possible to prevent static effects by instantaneous quenching of the extruded wire. Quenched products have microstructures in various stages of plastic deformation. Plots of 0.2% proof stress and elongation v. extrusion ratio exhibit two maxima which are a result of interaction between dynamic recrystallization and strain hardening. Above an extrusion ratio of about 90, th...
{"title":"Structure and strength of polycrystalline copper during hydrostatic extrusion with reduction up to R = 100","authors":"W. Pachla, L. Styczynski","doi":"10.1179/030634584790420311","DOIUrl":"https://doi.org/10.1179/030634584790420311","url":null,"abstract":"AbstractThe effect of extrusion ratios in the range 60–100 on the structure and strength of cold hydrostatically extruded. copper of 99.9% purity are reviewed. The final structure is mainly formed as a result of dynamic and static recrystallization and is controlled directly by the temperature generated in the die and the cooling rate at the die exit. Because of the high thermal effect of the process (T/T m … 0.54), products air cooled are fully recrystallized, the process having no dependence on the value of extrusion ratio used but being a result of the high efficiency of postdynamic recrystallization and secondary grain growth. It is possible to prevent static effects by instantaneous quenching of the extruded wire. Quenched products have microstructures in various stages of plastic deformation. Plots of 0.2% proof stress and elongation v. extrusion ratio exhibit two maxima which are a result of interaction between dynamic recrystallization and strain hardening. Above an extrusion ratio of about 90, th...","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"72 1","pages":"22-26"},"PeriodicalIF":0.0,"publicationDate":"1984-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86327635","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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