Pub Date : 1984-01-01DOI: 10.1179/030716984803274855
T. Savaşkan, E. Laufer
AbstractWear phenomena in a worn high-speed roller bearing made of ALSI 52100 steel were studied using metallography, electron-probe microanalysis, and microhardness measurements. Friction layers related to thermal effects were observed in the surface material of the bearing components, as already reported for sliding surfaces. A hard, martensitic, light-etching layer was observed on the surfaces of the rollers and the outer-ring raceway, while a soft dark-etching layer was observed on the surface of the inner-ring raceway. Failure of the bearing was due to excessive wear of the inner-ring raceway. Thus it was concluded that the most important harmful effect of the observed microstructural changes was to upset the hardness balance between roller surfaces and inner-ring raceway, leading to machining of the inner-ring raceway by the rollers. Surface pitting and other phenomena relating to rolling-contact fatigue were not significant wear mechanisms.
{"title":"Wear in a high-speed roller bearing","authors":"T. Savaşkan, E. Laufer","doi":"10.1179/030716984803274855","DOIUrl":"https://doi.org/10.1179/030716984803274855","url":null,"abstract":"AbstractWear phenomena in a worn high-speed roller bearing made of ALSI 52100 steel were studied using metallography, electron-probe microanalysis, and microhardness measurements. Friction layers related to thermal effects were observed in the surface material of the bearing components, as already reported for sliding surfaces. A hard, martensitic, light-etching layer was observed on the surfaces of the rollers and the outer-ring raceway, while a soft dark-etching layer was observed on the surface of the inner-ring raceway. Failure of the bearing was due to excessive wear of the inner-ring raceway. Thus it was concluded that the most important harmful effect of the observed microstructural changes was to upset the hardness balance between roller surfaces and inner-ring raceway, leading to machining of the inner-ring raceway by the rollers. Surface pitting and other phenomena relating to rolling-contact fatigue were not significant wear mechanisms.","PeriodicalId":18409,"journal":{"name":"Metals technology","volume":"47 1","pages":"530-534"},"PeriodicalIF":0.0,"publicationDate":"1984-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82830268","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: 10.1179/030716984803275214
K. Barlow, P. Lancaster, R. Maddison
AbstractThe authors examine three problems associated with the production of high-alloy steel bar and rod by rolling in hand-operated mills. An outline is given of the mechanics of formation of surface defects and, by using a model material for hot steel (Plasticine) as well as three grades of steel, the defects were examined. Although the work was carried out using hand-operated mills, the conclusions drawn are relevant to commercial continuous mills for producing low-alloy and carbon steel rod and bar. The defects examined were cracking, split ends, and decarburization. The main conclusion is that careful selection of pass sequence, taking into account all the manufacturing and product requirements, is essential in order to control the rate of rejection of rod and bar with these defects
{"title":"Examination of surface defects induced during hot rolling of high-alloy steel bar and rod","authors":"K. Barlow, P. Lancaster, R. Maddison","doi":"10.1179/030716984803275214","DOIUrl":"https://doi.org/10.1179/030716984803275214","url":null,"abstract":"AbstractThe authors examine three problems associated with the production of high-alloy steel bar and rod by rolling in hand-operated mills. An outline is given of the mechanics of formation of surface defects and, by using a model material for hot steel (Plasticine) as well as three grades of steel, the defects were examined. Although the work was carried out using hand-operated mills, the conclusions drawn are relevant to commercial continuous mills for producing low-alloy and carbon steel rod and bar. The defects examined were cracking, split ends, and decarburization. The main conclusion is that careful selection of pass sequence, taking into account all the manufacturing and product requirements, is essential in order to control the rate of rejection of rod and bar with these defects","PeriodicalId":18409,"journal":{"name":"Metals technology","volume":"261 1","pages":"14-19"},"PeriodicalIF":0.0,"publicationDate":"1984-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73024370","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: 10.1179/030716984803274503
N. Whitter, C. Hoskins
AbstractThe energy-intensive nature of metals processing means that the UK metals industries are of major importance in Government energy-conservation strategies. In the industries themselves, increasing costs in real terms have resulted in considerable research and development efforts, aimed at improving the efficiency with which energy is used by improving process control, by heat recovery and reuse, and by modification to processing routes. Examples of recent developments in converting bulk metal to semi-finished or finished products are given, and their importance is discussed.
{"title":"Energy required to process ingots, semis, and finished products","authors":"N. Whitter, C. Hoskins","doi":"10.1179/030716984803274503","DOIUrl":"https://doi.org/10.1179/030716984803274503","url":null,"abstract":"AbstractThe energy-intensive nature of metals processing means that the UK metals industries are of major importance in Government energy-conservation strategies. In the industries themselves, increasing costs in real terms have resulted in considerable research and development efforts, aimed at improving the efficiency with which energy is used by improving process control, by heat recovery and reuse, and by modification to processing routes. Examples of recent developments in converting bulk metal to semi-finished or finished products are given, and their importance is discussed.","PeriodicalId":18409,"journal":{"name":"Metals technology","volume":"19 1","pages":"300-307"},"PeriodicalIF":0.0,"publicationDate":"1984-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74066626","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: 10.1179/030716984803274639
C. Pitt, T. Pitt
AbstractComplete solid-solution treatment (SST) of CZ127 was found to be achieved only after heat treatment at 900°C. The increased SST temperature did not improve the mechanical properties of the aged material. The microstructures of SST CZ127 aged at temperatures between 200 and 700°C were examined using optical and transmission electron microscopy. A complex CuNiSi precipitate was found after 600 s heat treatment at all aging temperatures.
{"title":"Variations in mechanical properties and microstructure of CZ127 (Tungum or Ni–Al–Si α-brass) during aging after solution treatments at 800 and 900°C","authors":"C. Pitt, T. Pitt","doi":"10.1179/030716984803274639","DOIUrl":"https://doi.org/10.1179/030716984803274639","url":null,"abstract":"AbstractComplete solid-solution treatment (SST) of CZ127 was found to be achieved only after heat treatment at 900°C. The increased SST temperature did not improve the mechanical properties of the aged material. The microstructures of SST CZ127 aged at temperatures between 200 and 700°C were examined using optical and transmission electron microscopy. A complex CuNiSi precipitate was found after 600 s heat treatment at all aging temperatures.","PeriodicalId":18409,"journal":{"name":"Metals technology","volume":"68 1","pages":"145-148"},"PeriodicalIF":0.0,"publicationDate":"1984-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74066832","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: 10.1179/030716984803275007
F. Turner
AbstractTrace elements in superalloys can he grouped under three major headings, those which are detrimental to forgeability hut can he removed hy volatilization under vacuum, those which are detrimental and are not removed hy vacuum treatment hut can he comhined with neutralizers, and those elements which are generally regarded as being beneficial to forgeahility. It can he argued that all of the trace elements considered in this paper are detrimental to forgeahility and examples are given which illustrate that even the so-called beneficial elements can he detrimental given the appropriate circumstances. In this context the henefits to he gained by eliminating trace elements with neutralizers are compared and contrasted with the dangers which can occur from their inappropriate use. To put trace elements into context in today's alloys the various factors which affect forgeability are discussed in terms of forging environment and metallurgical factors. The methods of assessing forgeahility are briefly desc...
{"title":"Effect of trace elements on forgeability of superalloys","authors":"F. Turner","doi":"10.1179/030716984803275007","DOIUrl":"https://doi.org/10.1179/030716984803275007","url":null,"abstract":"AbstractTrace elements in superalloys can he grouped under three major headings, those which are detrimental to forgeability hut can he removed hy volatilization under vacuum, those which are detrimental and are not removed hy vacuum treatment hut can he comhined with neutralizers, and those elements which are generally regarded as being beneficial to forgeahility. It can he argued that all of the trace elements considered in this paper are detrimental to forgeahility and examples are given which illustrate that even the so-called beneficial elements can he detrimental given the appropriate circumstances. In this context the henefits to he gained by eliminating trace elements with neutralizers are compared and contrasted with the dangers which can occur from their inappropriate use. To put trace elements into context in today's alloys the various factors which affect forgeability are discussed in terms of forging environment and metallurgical factors. The methods of assessing forgeahility are briefly desc...","PeriodicalId":18409,"journal":{"name":"Metals technology","volume":"22 1","pages":"446-452"},"PeriodicalIF":0.0,"publicationDate":"1984-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79318001","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: 10.1179/030716984803274297
B. Krishnan, P. Rohatgi
AbstractThe variation in the size of silicon in commercial eutectic and hyper-eutectic Al–Si alloys owing to the presence of graphite particles of average size 40 11m, dispersed by the UPAL process, has been studied. The presence of dispersions equivalent to 3 wt-% of graphite particles (in gravity die cast Al–Si–graphite castings) results in about 37% reduction in the size of eutectic silicon in LM 13 alloy and 44% reduction in the size of primary silicon in LM 28 alloy, indicating the occurrence of partial modification and refinement of silicon in Al–Si alloys. When the concentration of graphite particles was as high as 15 wt-%, complete modification of silicon was observed. Procedures for achieving complete modification in Al–Si alloys containing 3 wt-% graphite using conventional modifiers have also been established. Silicon in LM 13–3graphite composite melts can be completely modified using sodium in elemental form or in commercially available salt form (Coveral-29A). With the help of microscopic and...
{"title":"Modification of Al–Si alloy melts containing graphite particle dispersions","authors":"B. Krishnan, P. Rohatgi","doi":"10.1179/030716984803274297","DOIUrl":"https://doi.org/10.1179/030716984803274297","url":null,"abstract":"AbstractThe variation in the size of silicon in commercial eutectic and hyper-eutectic Al–Si alloys owing to the presence of graphite particles of average size 40 11m, dispersed by the UPAL process, has been studied. The presence of dispersions equivalent to 3 wt-% of graphite particles (in gravity die cast Al–Si–graphite castings) results in about 37% reduction in the size of eutectic silicon in LM 13 alloy and 44% reduction in the size of primary silicon in LM 28 alloy, indicating the occurrence of partial modification and refinement of silicon in Al–Si alloys. When the concentration of graphite particles was as high as 15 wt-%, complete modification of silicon was observed. Procedures for achieving complete modification in Al–Si alloys containing 3 wt-% graphite using conventional modifiers have also been established. Silicon in LM 13–3graphite composite melts can be completely modified using sodium in elemental form or in commercially available salt form (Coveral-29A). With the help of microscopic and...","PeriodicalId":18409,"journal":{"name":"Metals technology","volume":"29 1","pages":"41-44"},"PeriodicalIF":0.0,"publicationDate":"1984-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74472729","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: 10.1179/030716984803275205
T. W. Clyne
AbstractA survey is presented of the processes employed to fabricate sheet products from primary aluminium ingots, encompassing DC (direct chill) semicontinuous casting (followed by annealing and hot rolling) and the various designs of strip caster. Some features of the solidification and growth conditions during these casting operations are described, and mention is made of some of the metallurgical factors relevant to quality control of the final product. A number of developmental processes that might be employed to fabricate aluminium strip are also described. In the context of the operational features outlined, assessments are made of the energy consumption, and possible energy savings are discussed in the light of the various practical aspects involved.
{"title":"Heat-flow, solidification, and energy aspects of DC and strip casting of aluminium alloys","authors":"T. W. Clyne","doi":"10.1179/030716984803275205","DOIUrl":"https://doi.org/10.1179/030716984803275205","url":null,"abstract":"AbstractA survey is presented of the processes employed to fabricate sheet products from primary aluminium ingots, encompassing DC (direct chill) semicontinuous casting (followed by annealing and hot rolling) and the various designs of strip caster. Some features of the solidification and growth conditions during these casting operations are described, and mention is made of some of the metallurgical factors relevant to quality control of the final product. A number of developmental processes that might be employed to fabricate aluminium strip are also described. In the context of the operational features outlined, assessments are made of the energy consumption, and possible energy savings are discussed in the light of the various practical aspects involved.","PeriodicalId":18409,"journal":{"name":"Metals technology","volume":"1 1","pages":"350-357"},"PeriodicalIF":0.0,"publicationDate":"1984-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76365753","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: 10.1179/030716984803274873
I. Chilton, A. T. Price, B. Wilshire
AbstractAustenitic-ferritic steel transition joints made with austenitic weld metal fail prematurely during service, because of the formation of intergranular cracks in the heat-affected zone (HAZ) of the ferritic steel at a distance of ∼ 75–150 Uml;m from the fusion boundary. This characteristic failure mode has been reproduced under uniaxial creep conditions by testing cross-weld specimens at temperatures between 838 and 923 K and at low stresses. Creep tests at high stress result in an entirely different fracture mode, with a more ductile failure occurring well outside the HAZ. The strains associated with these two modes have been examined using a microgrid technique and the failures are shown to be explicable in the terms of the differences in creep properties between the weld HAZ and the 2·25Cr-1 Mo ferritic steel plate.
{"title":"Creep deformation and local strain distributions in dissimilar metal vvelds betvveen AISI type 316 and 2–25Cr–1 Mo steels made vvith 17Cr–8Ni–2Mo weld metal","authors":"I. Chilton, A. T. Price, B. Wilshire","doi":"10.1179/030716984803274873","DOIUrl":"https://doi.org/10.1179/030716984803274873","url":null,"abstract":"AbstractAustenitic-ferritic steel transition joints made with austenitic weld metal fail prematurely during service, because of the formation of intergranular cracks in the heat-affected zone (HAZ) of the ferritic steel at a distance of ∼ 75–150 Uml;m from the fusion boundary. This characteristic failure mode has been reproduced under uniaxial creep conditions by testing cross-weld specimens at temperatures between 838 and 923 K and at low stresses. Creep tests at high stress result in an entirely different fracture mode, with a more ductile failure occurring well outside the HAZ. The strains associated with these two modes have been examined using a microgrid technique and the failures are shown to be explicable in the terms of the differences in creep properties between the weld HAZ and the 2·25Cr-1 Mo ferritic steel plate.","PeriodicalId":18409,"journal":{"name":"Metals technology","volume":"35 1","pages":"383-391"},"PeriodicalIF":0.0,"publicationDate":"1984-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77311082","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: 10.1179/030716984803274837
B. E. Q'Donnelly, R. Reuben, T. N. Baker
AbstractThe influence of various ferrite–pearlite microstructures on the hardness and proof stress of a range of C–Mn steels has been studied with respect to a Hall–Petch analysis. In contrast with previous reports, the average pearlite interlamellar spacing was best found to quantify the microstructure when account is also taken of the ferrite volume fraction, austenite grain size, and calculated cementite lamella thickness. The mean uninterrupted distance in the ferrite described by a simple law of mixtures was found to correlate well with measured hardness. Although this parameter gave good agreement with strength figures an improved prediction was suggested by considering an equation of the form σ ys C = σo + [K α + (K α − K α )V p ]d c −1/2, where the composite ferrite grain size d c can be expressed as d c 1/2 = V p d p 1/2 + V α d α 1/2, σo is the friction stress, and V p and V α are the volume fractions of pearlite and ferrite, respectively. Similarly, K p and K α are the Hall–Petch parameters for...
摘要采用Hall-Petch分析方法研究了不同铁素体-珠光体组织对C-Mn钢硬度和耐应力的影响。与之前的报道相反，当考虑到铁素体体积分数、奥氏体晶粒尺寸和计算出的渗碳体片层厚度时，平均珠光体片层间距最能量化微观组织。铁氧体中由简单混合定律描述的平均不间断距离与测量的硬度有很好的相关性。虽然这与强度参数给好的协议提出了一种改进的预测的数据考虑σy的方程形式C = o +σ[Kα+ (Kα−Kα)V p] d C−1/2,在复合的铁素体晶粒尺寸d C可以表示为d C p d p 1/2 + 1/2 = V dαα1/2,摩擦应力σo,和V p, Vα是珠光体和铁素体的体积分数,分别。同样，kp和K α是…的Hall-Petch参数。
{"title":"Quantitative assessment of strengthening parameters in ferrite-pearlite steels from microstructural measurements","authors":"B. E. Q'Donnelly, R. Reuben, T. N. Baker","doi":"10.1179/030716984803274837","DOIUrl":"https://doi.org/10.1179/030716984803274837","url":null,"abstract":"AbstractThe influence of various ferrite–pearlite microstructures on the hardness and proof stress of a range of C–Mn steels has been studied with respect to a Hall–Petch analysis. In contrast with previous reports, the average pearlite interlamellar spacing was best found to quantify the microstructure when account is also taken of the ferrite volume fraction, austenite grain size, and calculated cementite lamella thickness. The mean uninterrupted distance in the ferrite described by a simple law of mixtures was found to correlate well with measured hardness. Although this parameter gave good agreement with strength figures an improved prediction was suggested by considering an equation of the form σ ys C = σo + [K α + (K α − K α )V p ]d c −1/2, where the composite ferrite grain size d c can be expressed as d c 1/2 = V p d p 1/2 + V α d α 1/2, σo is the friction stress, and V p and V α are the volume fractions of pearlite and ferrite, respectively. Similarly, K p and K α are the Hall–Petch parameters for...","PeriodicalId":18409,"journal":{"name":"Metals technology","volume":"84 1","pages":"45-51"},"PeriodicalIF":0.0,"publicationDate":"1984-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85353733","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: 10.1179/030716984803274945
C. Varotto, M. A. Audero, D. Vassallo, Hector Jose Ruffo, R. Pascual
AbstractA method has been developed, and tested on a laboratory scale, to purify Zn obtained by the electrothermic process when Pb is the main impurity. It is based on thermal cycling the alloy around the melting temperature, inducing the phenomenon of gravity segregation during each thermal cycle. Results are reported on the effect of the number of cycles, cycle shape, and Pb concentration on the efficiency of the purification process. The separate contributions of the solidification and melting stages of the cycles are analysed. Based on the experimental results and on metallographic observations of the specimens, three mechanisms are proposed to explain qualitatively the segregation phenomena observed: (i) sedimentation of Pb-rich liquid droplets in the immiscible liquids of the monotectic Zn–Pb phase diagram; (ii) convective liquid motion; and (iii) sedimentation of Pb-rich globules during the heating part of the cycles. It was found that the last mechanism has the highest separation efficiency for th...
{"title":"Separation of components of Zn–Pb alloys by enhanced gravity segregation","authors":"C. Varotto, M. A. Audero, D. Vassallo, Hector Jose Ruffo, R. Pascual","doi":"10.1179/030716984803274945","DOIUrl":"https://doi.org/10.1179/030716984803274945","url":null,"abstract":"AbstractA method has been developed, and tested on a laboratory scale, to purify Zn obtained by the electrothermic process when Pb is the main impurity. It is based on thermal cycling the alloy around the melting temperature, inducing the phenomenon of gravity segregation during each thermal cycle. Results are reported on the effect of the number of cycles, cycle shape, and Pb concentration on the efficiency of the purification process. The separate contributions of the solidification and melting stages of the cycles are analysed. Based on the experimental results and on metallographic observations of the specimens, three mechanisms are proposed to explain qualitatively the segregation phenomena observed: (i) sedimentation of Pb-rich liquid droplets in the immiscible liquids of the monotectic Zn–Pb phase diagram; (ii) convective liquid motion; and (iii) sedimentation of Pb-rich globules during the heating part of the cycles. It was found that the last mechanism has the highest separation efficiency for th...","PeriodicalId":18409,"journal":{"name":"Metals technology","volume":"49 1","pages":"201-206"},"PeriodicalIF":0.0,"publicationDate":"1984-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84086831","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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