Pub Date : 1984-05-01DOI: 10.1179/030634584790420104
T. Gibbons, B. Hopkins
AbstractThe creep behaviour of a series of alloys based on IN 597 (Nimonic 101) and with varying volume fractions of γ′ precipitate has been studied at 800°C in the standard condition of heat treatment and for two grain sizes. In order to assess the long-term structural stability of alloys of this type, which have high contents of Cr, creep tests were also carried out on material overaged for 5000 and 10000 h at 850°C. Optical and electron metallography have been used to examine the microstructural characteristics of the materials. The results show a consistent pattern of increasing creep resistance with increasing volume fraction of γ′ precipitate, although the effect was more significant in the coarse grained material. After overaging, the creep resistance and the life to rupture of the alloys were reduced, and acicular particles, believed to be γ′ phase, were observed in the microstructure. Some limitations of current mechanisms describing dislocation–particle interactions are discussed with respect to...
{"title":"Creep behaviour and microstructure of Ni-Cr base alloys","authors":"T. Gibbons, B. Hopkins","doi":"10.1179/030634584790420104","DOIUrl":"https://doi.org/10.1179/030634584790420104","url":null,"abstract":"AbstractThe creep behaviour of a series of alloys based on IN 597 (Nimonic 101) and with varying volume fractions of γ′ precipitate has been studied at 800°C in the standard condition of heat treatment and for two grain sizes. In order to assess the long-term structural stability of alloys of this type, which have high contents of Cr, creep tests were also carried out on material overaged for 5000 and 10000 h at 850°C. Optical and electron metallography have been used to examine the microstructural characteristics of the materials. The results show a consistent pattern of increasing creep resistance with increasing volume fraction of γ′ precipitate, although the effect was more significant in the coarse grained material. After overaging, the creep resistance and the life to rupture of the alloys were reduced, and acicular particles, believed to be γ′ phase, were observed in the microstructure. Some limitations of current mechanisms describing dislocation–particle interactions are discussed with respect to...","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"37 1","pages":"273-280"},"PeriodicalIF":0.0,"publicationDate":"1984-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80335090","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 : 1984-05-01DOI: 10.1179/030634584790420122
T. V. Venkatasubramanian, T. Baker
AbstractThe role of MnS inclusions in the crack growth behaviour of quenched and tempered medium carbon steel exposed to H2S saturated salt solution has been studied. In this environment, crack extension in the short transverse orientations occurs in a discontinuous manner which is associated with the development of inclusion nucleated subsidiary cracks ahead of the main crack. The high hydrogen activity of the H2S saturated salt solution causes both matrix embrittlement and the accumulation of hydrogen at the inclusion/matrix interface in a molecular form. In the case of specimens containing pre-existing cracks, the formation of secondary cracks in the short transverse plane ahead of the main crack is caused by pressurization effects at colonies of closely spaced large inclusions. The discontinuous growth observed in these specimens is attributed to the operation of the pressurization mechanism.
{"title":"Role of MnS inclusions in hydrogen assisted cracking of steel exposed to H2S saturated salt solution","authors":"T. V. Venkatasubramanian, T. Baker","doi":"10.1179/030634584790420122","DOIUrl":"https://doi.org/10.1179/030634584790420122","url":null,"abstract":"AbstractThe role of MnS inclusions in the crack growth behaviour of quenched and tempered medium carbon steel exposed to H2S saturated salt solution has been studied. In this environment, crack extension in the short transverse orientations occurs in a discontinuous manner which is associated with the development of inclusion nucleated subsidiary cracks ahead of the main crack. The high hydrogen activity of the H2S saturated salt solution causes both matrix embrittlement and the accumulation of hydrogen at the inclusion/matrix interface in a molecular form. In the case of specimens containing pre-existing cracks, the formation of secondary cracks in the short transverse plane ahead of the main crack is caused by pressurization effects at colonies of closely spaced large inclusions. The discontinuous growth observed in these specimens is attributed to the operation of the pressurization mechanism.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"27 1","pages":"241-248"},"PeriodicalIF":0.0,"publicationDate":"1984-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87123310","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 : 1984-05-01DOI: 10.1179/030634584790420087
R. H. Bricknell, D. Woodford
Abstract Attempts to reverse the oxygen embrittlement caused by high temperature air exposure of nickel of various purities are described. It is shown that reversal can be effected in certain reducing environments in those grades of nickel having very low concentrations of metallic impurities, except in regions where heavy cavitation has occurred owing to gas formation. Oxygen embrittlement can similarly be prevented by prior annealing in hydrogen, but again only in the absence of significant metallic impurities. These results are explained on the basis of three distinct phenomena leading to embrittlement, and their implications are considered for the similar embrittlement observed in superalloys.
{"title":"Prevention and reversal of oxygen embrittlement in nickel","authors":"R. H. Bricknell, D. Woodford","doi":"10.1179/030634584790420087","DOIUrl":"https://doi.org/10.1179/030634584790420087","url":null,"abstract":"Abstract Attempts to reverse the oxygen embrittlement caused by high temperature air exposure of nickel of various purities are described. It is shown that reversal can be effected in certain reducing environments in those grades of nickel having very low concentrations of metallic impurities, except in regions where heavy cavitation has occurred owing to gas formation. Oxygen embrittlement can similarly be prevented by prior annealing in hydrogen, but again only in the absence of significant metallic impurities. These results are explained on the basis of three distinct phenomena leading to embrittlement, and their implications are considered for the similar embrittlement observed in superalloys.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"2007 1","pages":"265-272"},"PeriodicalIF":0.0,"publicationDate":"1984-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88279297","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 : 1984-05-01DOI: 10.1179/030634584790420096
T. Sheppard, M. Zaidi
AbstractAl-7Mg rapidly solidified powders were processed by extrusion to prepare billets for rolling. The billets were rolled at temperatures between 300 and 500°C and tested in tension. The fracture surfaces were examined and this paper illustrates that in the absence of larger precipitates the fracture mechanism is dependent upon the oxide content and morphology inherent in the air atomized powders. When larger particles are present (1–3 μm), the fracture is initiated and propagated by the particles; the oxide does not feature in the fracture process. Some billets were rolled in multi passes and it is shown that a maximum of about 40% reduction may be obtained before the oxide particles cause exfoliation by fracture at prior particle boundaries. It is concluded that the thermomechanical process route for the production of engineering materials must pay particular attention to the distribution of the oxide film and to maintaining the thermal stablhty of the atomized powders.
{"title":"Mechanics of fracture in hot rolled Al-7Mg alloy prepared from rapidly solidified powder","authors":"T. Sheppard, M. Zaidi","doi":"10.1179/030634584790420096","DOIUrl":"https://doi.org/10.1179/030634584790420096","url":null,"abstract":"AbstractAl-7Mg rapidly solidified powders were processed by extrusion to prepare billets for rolling. The billets were rolled at temperatures between 300 and 500°C and tested in tension. The fracture surfaces were examined and this paper illustrates that in the absence of larger precipitates the fracture mechanism is dependent upon the oxide content and morphology inherent in the air atomized powders. When larger particles are present (1–3 μm), the fracture is initiated and propagated by the particles; the oxide does not feature in the fracture process. Some billets were rolled in multi passes and it is shown that a maximum of about 40% reduction may be obtained before the oxide particles cause exfoliation by fracture at prior particle boundaries. It is concluded that the thermomechanical process route for the production of engineering materials must pay particular attention to the distribution of the oxide film and to maintaining the thermal stablhty of the atomized powders.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"12 1","pages":"236-240"},"PeriodicalIF":0.0,"publicationDate":"1984-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79846299","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 : 1984-05-01DOI: 10.1179/030634584790420078
H. Shen, T. Lei
AbstractConsidering the similarities between structural distribution and deformation behaviour of martensite–ferrite dual phase steels with composite materials reinforced by short, discontinuous fibres, a new expression for the tensile strength of these steels was suggested using shear lag analysis, i.e. σ bDP = 1 K ( β 2 3 + 0 ⋅ 65 ) σ bM V M + σ bF
摘要考虑到短不连续纤维增强马氏体-铁素体双相钢的组织分布和变形行为的相似性，利用剪切滞后分析提出了马氏体-铁素体双相钢抗拉强度的新表达式:σ bDP = 1 K (β 2 3 + 0⋅65)σ bM V M + σ bF
{"title":"Shear lag analysis of strength of dual phase steels","authors":"H. Shen, T. Lei","doi":"10.1179/030634584790420078","DOIUrl":"https://doi.org/10.1179/030634584790420078","url":null,"abstract":"AbstractConsidering the similarities between structural distribution and deformation behaviour of martensite–ferrite dual phase steels with composite materials reinforced by short, discontinuous fibres, a new expression for the tensile strength of these steels was suggested using shear lag analysis, i.e. σ bDP = 1 K ( β 2 3 + 0 ⋅ 65 ) σ bM V M + σ bF","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"30 2 1","pages":"257-264"},"PeriodicalIF":0.0,"publicationDate":"1984-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90070503","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 : 1984-04-01DOI: 10.1179/030634584790420195
K. Kurzydłowski, W. Zieliński
AbstractFor the materials used in the construction of power installations there are set minimum operating time requirements. The estimated operating time of such installations amounts to some 100000 h. For reasons of economy, it is sometimes necessary to extend this period. Therefore, the materials used must be characterized by considerable structural stability under the temperature and load conditions occurring in such installations.
{"title":"Mo2C → M6C carbide transformation in low alloy Cr-Mo ferritic steels","authors":"K. Kurzydłowski, W. Zieliński","doi":"10.1179/030634584790420195","DOIUrl":"https://doi.org/10.1179/030634584790420195","url":null,"abstract":"AbstractFor the materials used in the construction of power installations there are set minimum operating time requirements. The estimated operating time of such installations amounts to some 100000 h. For reasons of economy, it is sometimes necessary to extend this period. Therefore, the materials used must be characterized by considerable structural stability under the temperature and load conditions occurring in such installations.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"13 1","pages":"223-224"},"PeriodicalIF":0.0,"publicationDate":"1984-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82218166","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 : 1984-04-01DOI: 10.1179/030634584790420168
T. Okamoto, X. Huang, A. Kagawa
AbstractArgon atmosphere pressure had no effect on the nodularization of graphite in magnesium treated cast iron, while it had considerable influence on the graphitization and graphite nodule number. With increasing argon atmosphere pressure up to 145 atm, the graphitization was retarded and the graphite nodule number reduced. The degree of nodularization became maximum at a magnesium content of about 0.15 mass-% and thereafter decreased as the magnesium content increased. For values >0.15 mass-%Mg, meshlike and flaky graphite was formed in the region adjacent to tiny particles which proved to be magnesium droplets. The effect of magnesium on the graphitization was opposite to that on the nodularization of graphite, i.e. the graphitization was suppressed with increasing magnesium content up to about 0.15 mass-% and was promoted when the magnesium content exceeded 0.15 mass-%.
{"title":"Graphite nodularization and graphitization of magnesium treated cast irons solidified under argon atmosphere pressure up to 145 atm","authors":"T. Okamoto, X. Huang, A. Kagawa","doi":"10.1179/030634584790420168","DOIUrl":"https://doi.org/10.1179/030634584790420168","url":null,"abstract":"AbstractArgon atmosphere pressure had no effect on the nodularization of graphite in magnesium treated cast iron, while it had considerable influence on the graphitization and graphite nodule number. With increasing argon atmosphere pressure up to 145 atm, the graphitization was retarded and the graphite nodule number reduced. The degree of nodularization became maximum at a magnesium content of about 0.15 mass-% and thereafter decreased as the magnesium content increased. For values >0.15 mass-%Mg, meshlike and flaky graphite was formed in the region adjacent to tiny particles which proved to be magnesium droplets. The effect of magnesium on the graphitization was opposite to that on the nodularization of graphite, i.e. the graphitization was suppressed with increasing magnesium content up to about 0.15 mass-% and was promoted when the magnesium content exceeded 0.15 mass-%.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"9 1","pages":"169-176"},"PeriodicalIF":0.0,"publicationDate":"1984-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78820620","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 : 1984-04-01DOI: 10.1179/030634584790420177
A. Korbel, W. Bochniak, L. Błaż, J. Embury
Abstract The present paper shows the results of high temperature experiments performed on Cu single crystals. The crystals were deformed by rolling at 900°C with the rolling plane either parallel to {123} or 14° off the {111} crystal plane. In the former, slip events were evenly distributed in the samples. No recrystallization was then observed. For the crystals which were 14° off the {111} plane, the deformation was non-uniform and numerous shear bands were formed. It was found that the density of shear bands increased with strain, and recrystallization initiated within the shear bands. A model of dynamic recrystallization in crystals deforming by the shear band mode is discussed in terms of the structural features revealed by optical and electron microscopy.
{"title":"Instability of plastic flow and dynamic recrystallization in Cu single crystals","authors":"A. Korbel, W. Bochniak, L. Błaż, J. Embury","doi":"10.1179/030634584790420177","DOIUrl":"https://doi.org/10.1179/030634584790420177","url":null,"abstract":"Abstract The present paper shows the results of high temperature experiments performed on Cu single crystals. The crystals were deformed by rolling at 900°C with the rolling plane either parallel to {123} or 14° off the {111} crystal plane. In the former, slip events were evenly distributed in the samples. No recrystallization was then observed. For the crystals which were 14° off the {111} plane, the deformation was non-uniform and numerous shear bands were formed. It was found that the density of shear bands increased with strain, and recrystallization initiated within the shear bands. A model of dynamic recrystallization in crystals deforming by the shear band mode is discussed in terms of the structural features revealed by optical and electron microscopy.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"80 1","pages":"216-222"},"PeriodicalIF":0.0,"publicationDate":"1984-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91225827","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 : 1984-04-01DOI: 10.1179/030634584790420186
S. E. Franklin, R. A. Stark
AbstractOne of the principal objectives of this investigation was to utilize the high sensitivity to all elements of secondary ion mass spectrometry in a study of the distribution of particular elements in a variety of cast iron microstructures. The information acquired is then used in an attempt to clarify the role of these elements in graphite nucleation and growth mechanisms. The only similar study using this technique was restricted to graphite nodules and flakes with emphasis placed on the segregation of elements to the interface and in the surrounding matrix. This present study includes other graphite morphologies and pays attention to the segregation of elements within the graphite phase.
{"title":"Application of secondary ion mass spectrometry to study of graphite morphology in cast iron","authors":"S. E. Franklin, R. A. Stark","doi":"10.1179/030634584790420186","DOIUrl":"https://doi.org/10.1179/030634584790420186","url":null,"abstract":"AbstractOne of the principal objectives of this investigation was to utilize the high sensitivity to all elements of secondary ion mass spectrometry in a study of the distribution of particular elements in a variety of cast iron microstructures. The information acquired is then used in an attempt to clarify the role of these elements in graphite nucleation and growth mechanisms. The only similar study using this technique was restricted to graphite nodules and flakes with emphasis placed on the segregation of elements to the interface and in the surrounding matrix. This present study includes other graphite morphologies and pays attention to the segregation of elements within the graphite phase.","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"76 1","pages":"187-200"},"PeriodicalIF":0.0,"publicationDate":"1984-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85785933","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 : 1984-04-01DOI: 10.1179/030634584790420159
U. Lenel, R. Honeycombe
AbstractThe formation of austenite from a ferrite–carbide microstructure in an Fe-10Cr-0.2C (wt-%) alloy has been investigated by optical and transmission electron microscopy and microanalysis of partially transformed and quenched samples. Although nucleation of austenite is relatively sluggish (compared to low alloys steels), growth of austenite is rapid and the reaction is complete within 100 s at temperatures above AC 3. The transformation proceeds more rapidly as the temperature increases. Fine undissolved carbides have little effect on the movement of the austenite growth front while closely spaced coarse carbides can pin the interface. Carbides do not dissolve in ferrite or in the ferrite/austenite interface (unless the interface is stationary owing to pinning) but the higher solubility of carbon in austenite allows dissolution of carbides in austenite to occur. The rate of dissolution is controlled by the rate of removal of chromium. Austenite inherits the chromium content of the ferrite and no par...
{"title":"Formation of austenite in Fe-10Cr-0.2C alloy","authors":"U. Lenel, R. Honeycombe","doi":"10.1179/030634584790420159","DOIUrl":"https://doi.org/10.1179/030634584790420159","url":null,"abstract":"AbstractThe formation of austenite from a ferrite–carbide microstructure in an Fe-10Cr-0.2C (wt-%) alloy has been investigated by optical and transmission electron microscopy and microanalysis of partially transformed and quenched samples. Although nucleation of austenite is relatively sluggish (compared to low alloys steels), growth of austenite is rapid and the reaction is complete within 100 s at temperatures above AC 3. The transformation proceeds more rapidly as the temperature increases. Fine undissolved carbides have little effect on the movement of the austenite growth front while closely spaced coarse carbides can pin the interface. Carbides do not dissolve in ferrite or in the ferrite/austenite interface (unless the interface is stationary owing to pinning) but the higher solubility of carbon in austenite allows dissolution of carbides in austenite to occur. The rate of dissolution is controlled by the rate of removal of chromium. Austenite inherits the chromium content of the ferrite and no par...","PeriodicalId":18750,"journal":{"name":"Metal science","volume":"12 1","pages":"201-206"},"PeriodicalIF":0.0,"publicationDate":"1984-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83584820","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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