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Properties of roller compacted concrete using Portland blast furnace slag cement
data to the case of naturally occurringdefects in engineering hardware. This letter considersthis problem for short cracks in Q1N (HY80) steel. Artificial intelligence in the eddy current inspection of aircraft engine component,,. Chapman, C.E., Fahr, A., Pelletier, A. and Hay, D.R. Mater. EvaL Sept. 1991 49 (9) 1090-1092, 1094 An artificial intelligence method, pattern recognition, was used to develop an improved automated inspection system, ARIES, to detect small low-cycle fatigue cracks in fastener boltholes of aircraft engine compressor disks, spacers, and other rotating parts. The speed and accuracy of computers, combined with human insight and experience in detecting minute defects, provide a cost-effective real-time method with improved sensitivity and reliability. The compressor disk material was AM355
steel. Detection and analysis of defects in reactor pressure components by location and interpretation of acoustic emission sources. Deuster, G., Sklarczyk, C. and Waschkies, E. Nucl. Eng. Des. 1991 129 (2) 185-190 In the last years many hydrotests, cyclic fatigue tests, and thermal shock tests have been carried OUt on reactor pressure vessels, which exhibited crack-like defects, with the aim of developing the conditions of detectability of growing and nongrowing cracks by acoustic emission (AE). The AE generated during these experiments has been recorded and analysed. Techniques for evaluation of AE data have been developed which allowed the separation of AE events from crack growth and crack surface friction by risatime. Crack growth can be detected with high sensitivity at thermal shock and fatigue tests, whereas the detectability of crack surface friction by risetime. Crack growth can be detected with high sensitivity at thermal shock and fatigue tests, whereas the detectability of crack surface friction increases,as the amount of compressive stresses between the crack surface grows. At hydrotest only a low-level AE is produced by non-growing cracks due to the lack of compressive stresses.
and automated test method development for investigation o • f s Orbison, t i J.G.,mPeterec,eR.H., Carhart, n J.A. and Rich, I.P. i~u,e crack initiation.
Finite elements Anal. Des. Oct, 1991 10 (1) 9-25 An economic and effective test specimen has been developed for use in fatigue crack initiation studies, A dynamic materials-testing system was similarly developed for this purpose, consisting of a servohydraulic dynamic testing unit, high-resolution photomacrographic equipment, and computer control systems. The specimen and system permit fully automated fatigue crack initiation testing, and crack lengths approx 0.001 in have been detected with the peak load amplitude applied to the specimen. The development of the specimen, the design constraints imposed by the system and the required test results, and the prototype test program and subsequent specimen modifications are presented. Final specimen dimensions, the correlation between notch root stress and applied load, and recommendations for specimen use are also provided, Aluminium base alloy castings and 4340 steels were tested.
General Investigation of gudgeon pin failure in diesel engine. Verma, A. Tool and Alloy Steels Sept. 1991 25 (9) 341-347 A case study of recurrent premature failures of gudgeon pins (AISI 5015) in diesel engines is presented. Deficiency in manufacturing is analysed to be the cause of fatigue failures in this component. A stricter quality control and corrective measures in manufacturing have led to averting failures.
Improved methods for testing bond and intrinsic strength and fatigue of thermally sprayed metallic and ceramic coatings. Schweitzer, K.K. and Ziehl, M.H. and Schwaminger, Ch. Surf. Coal Technol. Nov. 1991 48 (2) 103-112 Conventional bond strength tests for thermally sprayed coatings represent only a rough means of obtaining overall strength values, with no differentiation between adhesion at the interface and intrinsic coating properties. To obtain information about the influence of substrata preparation on the adhesion of a Tribaloy T700 coating, tensile bond strength and modified crack-opening displacement (COD) specimens were tested by deliberate crack initiation at the interface. Crack initiation was achieved by weakening of the interface at the outer diameter in the case of bond strength specimens or at the notch root in the case of COD specimens. This made it possible to look at the influence of surface roughness and grit contamination on the coating adhesion separately. Modified COD specimens with the notch in the centre of the coating were used to determine crack-opening energies and critical stress intensity factors of atmospheric plasma-sprayed NiAI and low-pressure plasma-sprayed CoNiCrAIY bond coatings, and a ZrO2 7Yz 03 thermal barrier coating (TBC). Additionally, bond strength specimens were stressed dynamically, and it could be demonstrated that Wohler (S/N) diagrams can be established for a metallic NiAI bond coating and even for a ceramic ZrO2 7Y2 03 TBC. Coatings were sprayed on (nconel 719.
Improvement of mechanical properties of type 403 stainless steel by pulse-induction hardening. Albertin, L., Liaw, P.K., Burke, M.G. and Frohlich, R.L. Scr. Metall. Mater. Nov. 1991 25 (11) 2448-2450 Pulse hardening is a high-power-density induction technique which heats a local surface area of an Fe alloy by short, high-frequency induction phases. The effect of pulse-induction hardening on the metallurgical, tensile, and fatigue properties of Type 403 stainless steels can be summarized as follows: the process refined the grain size, increased the local hardness, improved the notch tensile strength, introduced compressive residual stresses at the surface, and raised the notched fatigue strength.
Int J Fatigue September 1992
Effect of tempering time on fatigue strength of Ni-Cr steel. Haga, T. and Noguchi, T. J. Jpn Inst. Met. Sept. 1991 55 (9) 915-921 (in Japanese) Bending fatigue test was carried out on specimens of Ni-Cr steel (Fe-0.28C-0.72Ni-0.75Cr-0.5Mn-0.26Si) quenched and tempered at various temperatures, and a comparative study was made on fatigue limit and crack extension rate. particularly with regard to the influence of tempering time. Fatigue strength was clearly influenced by tempering time, while hardness showed little variation with tempering time. Specimens tempered at 623 and 723 K showed the lowest fatigue limit at holding time of 2.4 ks, but it increased in specimens with both shorter holding time (1.2 ks) and longer holding time (4.8 and 7.2 ks) showing that the fatigue strength was improved. However, the specimens tempered at 673 and 873 K showed the highest fatigue strength at holding time 2.4 ks, decreasing with shorter and longer holding time. In all the specimens, the lowering of fatigue strength was identified by a characteristic microfracture appearance with quasi-cleavage facets in striation-like markings. With long holding time (7.2 ks), the m value that characterizes crack propagation rate was decreased to 1.4 for all the specimens as compared with the m value of 1.7-2.4 in specimens tempered for 2.4 ks. This suggested that crack propagation rate was late with tempering time.
Properties of roller compacted concrete using Portland blast furnace slag cement. Chikada, T. and Matsushita, H. J. Soc. Mater. Sci. Jpn Sept. 1991 40 (456) 1228-1234 (in Japanese) Recently, roller-compacted concrete is being used increasingly as a material for concrete dams and concrete pavement. The construction method for these structures requires no slump concrete, because the concrete is transported by damp trucks and compacted by vibrating rollers. It is essentially important to design an adequate mix proportion in concrete and to compact sufficiently at the field for rollercompacted concrete, Usage of Portland blast furnace slag cement has increased for concrete construction in Japan, because the cement contributes to energy saving and improvement of concrete durability. Mixing tests for roller-compacted concrete using Portland blast furnace slag cement were carried out to determine the optimum mix proportion through testing of various properties of hardened concrete, such as flexural strength, length change, resistances for freezing and thawing cycles, and fatigue strength. Consequently, the use of Portland blast furnace slag cement was found to be quite effective as the cementitious material for roller-compacted concrete, except in the case in which early-age strength is required. Furthermore, the properties of the hardened roller-compacted concrete were found to be much influenced by the compaction degree of the concrete. Case histories on surgical i m p l a n t s and their causes. Zitter, H. Werkst. Korros. Sept. 1991 42 (9) 455-466 (in German) The third decade of an evaluation of inadequate implants reveals that the kinds of critical cases have not changed essentially. These cases are corrosion fatigue or fatigue caused by structural grooves and local corrosion. Pitting and crevice corrosion were exclusively observed on implants of Cr-Ni-Mo steels with insufficient pitting resistance equivalents (% Cr + 3x % Mo). Fatigue is also brought about by the fact that the mechanical strength of implant alloys is often not optimally adjusted to the specific function of the implants. On these requirements national and international standards are not sufficient.
Magnetron sputter temperature alloys. Kuznetsov, E.V. and Surf. Coat. Technol.
deposition of heat-resistant coatings on high Beregovsky, V.V., Shergin, G.G., Shesterkin, N.G., Anisimova, M.A. Oct. 1991 48 (1) 13-18
The experiments were carried out in a unit with two planar magnetrons arranged according to a scheme of the 'face-to-face' type. Co-Cr-AI-Y coatings were applied on specimens for mechanical and thermal fatigue, long term strength, sulphidation-oxidation corrosion tests, and for metallographic study, it was established that coating increases the corrosion resistance of alloys without any deterioration of their service properties, ft has been shown that layer-by-layer alternation of CoAl end Co(CrAI) phases in Co-Cr-AI-Y coatings improves the hightemperature fatigue properties of the substrate. The use of high substrate bias during coating deposition leads to changes in the coating chemical composition along the blade profile, In this case the Cr content, for example, is inversely dependent upon the ion current density, Samples of Ni base superalloy CNK7RS were coated with Co-22Cr-9AI-0.5Y.
Fracture and fatigue of GCr15 steel. Fang, Q. and Ma, X. Xi'an Jiaotong Daxue Xuerbao (J. Xi'an Jiaotong Univ.) 1991 25 (2) 135-141 (in Chinese) The influence of heat treatment on fracture toughness Kic and fatigue crack growth rate da/dN in GCr15 steel is discussed. The results show that the composition and rnicrostructure of the matrix in GCr15 steel are major factors in the influence on fracture toughness and fatigue crack growth rates. Fracture toughness decreases and fatigue crack growth rates increase with raising austenitizing temperatures for hardening. Fracture toughness increases and fatigue crack growth rates decrease with raising tempering temperatures. But Kic decreases and da/dN increase rapidly at 230 °C because of the effect of tempered martensite embrittlement (TME). Observations of crack growth process and SEM analyses of fatigue crack surfaces in GCr15 steel suggest that the intergranular fracture in the near threshold region prevails. The interrupted renucleation of the fatigue crack in the intermediate crack growth rate region, and the quasi-cleavage with intergranular fracture in the fast crack growth region were observed.
The development of an improved 2% C r - M o - N i - W - V HP/IP rotor material. Wiemann, W. and Marriott, J.B. Commission of the European Communities Report No. EUR 13452, 1991 95 pp Current high-pressure (HP) and intermediate-pressure (IP) steam turbine rotors are normally forged from 1% Cr-Mo-(Ni)-V alloy steels. A steel with similar physical properties to the conventional type but with distinctly higher toughness and at least comparable creep behaviour would offer great advantages. Such a steel has been developed by one steelmaker, Saarstaht, with the composition 2% Cr-Mo-Ni-W-V. Material from two rotor forgings with diameters of 1000 and 1390 mm, respectively, manufactured by VCD and ESR routes was examined for chemical composition, microstructure, and heat treatment effects. Appropriate physical properties were
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steel. Detection and analysis of defects in reactor pressure components by location and interpretation of acoustic emission sources. Deuster, G., Sklarczyk, C. and Waschkies, E. Nucl. Eng. Des. 1991 129 (2) 185-190 In the last years many hydrotests, cyclic fatigue tests, and thermal shock tests have been carried OUt on reactor pressure vessels, which exhibited crack-like defects, with the aim of developing the conditions of detectability of growing and nongrowing cracks by acoustic emission (AE). The AE generated during these experiments has been recorded and analysed. Techniques for evaluation of AE data have been developed which allowed the separation of AE events from crack growth and crack surface friction by risatime. Crack growth can be detected with high sensitivity at thermal shock and fatigue tests, whereas the detectability of crack surface friction by risetime. Crack growth can be detected with high sensitivity at thermal shock and fatigue tests, whereas the detectability of crack surface friction increases,as the amount of compressive stresses between the crack surface grows. At hydrotest only a low-level AE is produced by non-growing cracks due to the lack of compressive stresses.
and automated test method development for investigation o • f s Orbison, t i J.G.,mPeterec,eR.H., Carhart, n J.A. and Rich, I.P. i~u,e crack initiation.
Finite elements Anal. Des. Oct, 1991 10 (1) 9-25 An economic and effective test specimen has been developed for use in fatigue crack initiation studies, A dynamic materials-testing system was similarly developed for this purpose, consisting of a servohydraulic dynamic testing unit, high-resolution photomacrographic equipment, and computer control systems. The specimen and system permit fully automated fatigue crack initiation testing, and crack lengths approx 0.001 in have been detected with the peak load amplitude applied to the specimen. The development of the specimen, the design constraints imposed by the system and the required test results, and the prototype test program and subsequent specimen modifications are presented. Final specimen dimensions, the correlation between notch root stress and applied load, and recommendations for specimen use are also provided, Aluminium base alloy castings and 4340 steels were tested.
General Investigation of gudgeon pin failure in diesel engine. Verma, A. Tool and Alloy Steels Sept. 1991 25 (9) 341-347 A case study of recurrent premature failures of gudgeon pins (AISI 5015) in diesel engines is presented. Deficiency in manufacturing is analysed to be the cause of fatigue failures in this component. A stricter quality control and corrective measures in manufacturing have led to averting failures.
Improved methods for testing bond and intrinsic strength and fatigue of thermally sprayed metallic and ceramic coatings. Schweitzer, K.K. and Ziehl, M.H. and Schwaminger, Ch. Surf. Coal Technol. Nov. 1991 48 (2) 103-112 Conventional bond strength tests for thermally sprayed coatings represent only a rough means of obtaining overall strength values, with no differentiation between adhesion at the interface and intrinsic coating properties. To obtain information about the influence of substrata preparation on the adhesion of a Tribaloy T700 coating, tensile bond strength and modified crack-opening displacement (COD) specimens were tested by deliberate crack initiation at the interface. Crack initiation was achieved by weakening of the interface at the outer diameter in the case of bond strength specimens or at the notch root in the case of COD specimens. This made it possible to look at the influence of surface roughness and grit contamination on the coating adhesion separately. Modified COD specimens with the notch in the centre of the coating were used to determine crack-opening energies and critical stress intensity factors of atmospheric plasma-sprayed NiAI and low-pressure plasma-sprayed CoNiCrAIY bond coatings, and a ZrO2 7Yz 03 thermal barrier coating (TBC). Additionally, bond strength specimens were stressed dynamically, and it could be demonstrated that Wohler (S/N) diagrams can be established for a metallic NiAI bond coating and even for a ceramic ZrO2 7Y2 03 TBC. Coatings were sprayed on (nconel 719.
Improvement of mechanical properties of type 403 stainless steel by pulse-induction hardening. Albertin, L., Liaw, P.K., Burke, M.G. and Frohlich, R.L. Scr. Metall. Mater. Nov. 1991 25 (11) 2448-2450 Pulse hardening is a high-power-density induction technique which heats a local surface area of an Fe alloy by short, high-frequency induction phases. The effect of pulse-induction hardening on the metallurgical, tensile, and fatigue properties of Type 403 stainless steels can be summarized as follows: the process refined the grain size, increased the local hardness, improved the notch tensile strength, introduced compressive residual stresses at the surface, and raised the notched fatigue strength.
Int J Fatigue September 1992
Effect of tempering time on fatigue strength of Ni-Cr steel. Haga, T. and Noguchi, T. J. Jpn Inst. Met. Sept. 1991 55 (9) 915-921 (in Japanese) Bending fatigue test was carried out on specimens of Ni-Cr steel (Fe-0.28C-0.72Ni-0.75Cr-0.5Mn-0.26Si) quenched and tempered at various temperatures, and a comparative study was made on fatigue limit and crack extension rate. particularly with regard to the influence of tempering time. Fatigue strength was clearly influenced by tempering time, while hardness showed little variation with tempering time. Specimens tempered at 623 and 723 K showed the lowest fatigue limit at holding time of 2.4 ks, but it increased in specimens with both shorter holding time (1.2 ks) and longer holding time (4.8 and 7.2 ks) showing that the fatigue strength was improved. However, the specimens tempered at 673 and 873 K showed the highest fatigue strength at holding time 2.4 ks, decreasing with shorter and longer holding time. In all the specimens, the lowering of fatigue strength was identified by a characteristic microfracture appearance with quasi-cleavage facets in striation-like markings. With long holding time (7.2 ks), the m value that characterizes crack propagation rate was decreased to 1.4 for all the specimens as compared with the m value of 1.7-2.4 in specimens tempered for 2.4 ks. This suggested that crack propagation rate was late with tempering time.
Properties of roller compacted concrete using Portland blast furnace slag cement. Chikada, T. and Matsushita, H. J. Soc. Mater. Sci. Jpn Sept. 1991 40 (456) 1228-1234 (in Japanese) Recently, roller-compacted concrete is being used increasingly as a material for concrete dams and concrete pavement. The construction method for these structures requires no slump concrete, because the concrete is transported by damp trucks and compacted by vibrating rollers. It is essentially important to design an adequate mix proportion in concrete and to compact sufficiently at the field for rollercompacted concrete, Usage of Portland blast furnace slag cement has increased for concrete construction in Japan, because the cement contributes to energy saving and improvement of concrete durability. Mixing tests for roller-compacted concrete using Portland blast furnace slag cement were carried out to determine the optimum mix proportion through testing of various properties of hardened concrete, such as flexural strength, length change, resistances for freezing and thawing cycles, and fatigue strength. Consequently, the use of Portland blast furnace slag cement was found to be quite effective as the cementitious material for roller-compacted concrete, except in the case in which early-age strength is required. Furthermore, the properties of the hardened roller-compacted concrete were found to be much influenced by the compaction degree of the concrete. Case histories on surgical i m p l a n t s and their causes. Zitter, H. Werkst. Korros. Sept. 1991 42 (9) 455-466 (in German) The third decade of an evaluation of inadequate implants reveals that the kinds of critical cases have not changed essentially. These cases are corrosion fatigue or fatigue caused by structural grooves and local corrosion. Pitting and crevice corrosion were exclusively observed on implants of Cr-Ni-Mo steels with insufficient pitting resistance equivalents (% Cr + 3x % Mo). Fatigue is also brought about by the fact that the mechanical strength of implant alloys is often not optimally adjusted to the specific function of the implants. On these requirements national and international standards are not sufficient.
Magnetron sputter temperature alloys. Kuznetsov, E.V. and Surf. Coat. Technol.
deposition of heat-resistant coatings on high Beregovsky, V.V., Shergin, G.G., Shesterkin, N.G., Anisimova, M.A. Oct. 1991 48 (1) 13-18
The experiments were carried out in a unit with two planar magnetrons arranged according to a scheme of the 'face-to-face' type. Co-Cr-AI-Y coatings were applied on specimens for mechanical and thermal fatigue, long term strength, sulphidation-oxidation corrosion tests, and for metallographic study, it was established that coating increases the corrosion resistance of alloys without any deterioration of their service properties, ft has been shown that layer-by-layer alternation of CoAl end Co(CrAI) phases in Co-Cr-AI-Y coatings improves the hightemperature fatigue properties of the substrate. The use of high substrate bias during coating deposition leads to changes in the coating chemical composition along the blade profile, In this case the Cr content, for example, is inversely dependent upon the ion current density, Samples of Ni base superalloy CNK7RS were coated with Co-22Cr-9AI-0.5Y.
Fracture and fatigue of GCr15 steel. Fang, Q. and Ma, X. Xi'an Jiaotong Daxue Xuerbao (J. Xi'an Jiaotong Univ.) 1991 25 (2) 135-141 (in Chinese) The influence of heat treatment on fracture toughness Kic and fatigue crack growth rate da/dN in GCr15 steel is discussed. The results show that the composition and rnicrostructure of the matrix in GCr15 steel are major factors in the influence on fracture toughness and fatigue crack growth rates. Fracture toughness decreases and fatigue crack growth rates increase with raising austenitizing temperatures for hardening. Fracture toughness increases and fatigue crack growth rates decrease with raising tempering temperatures. But Kic decreases and da/dN increase rapidly at 230 °C because of the effect of tempered martensite embrittlement (TME). Observations of crack growth process and SEM analyses of fatigue crack surfaces in GCr15 steel suggest that the intergranular fracture in the near threshold region prevails. The interrupted renucleation of the fatigue crack in the intermediate crack growth rate region, and the quasi-cleavage with intergranular fracture in the fast crack growth region were observed.
The development of an improved 2% C r - M o - N i - W - V HP/IP rotor material. Wiemann, W. and Marriott, J.B. Commission of the European Communities Report No. EUR 13452, 1991 95 pp Current high-pressure (HP) and intermediate-pressure (IP) steam turbine rotors are normally forged from 1% Cr-Mo-(Ni)-V alloy steels. A steel with similar physical properties to the conventional type but with distinctly higher toughness and at least comparable creep behaviour would offer great advantages. Such a steel has been developed by one steelmaker, Saarstaht, with the composition 2% Cr-Mo-Ni-W-V. Material from two rotor forgings with diameters of 1000 and 1390 mm, respectively, manufactured by VCD and ESR routes was examined for chemical composition, microstructure, and heat treatment effects. Appropriate physical properties were
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