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Study on the impact fatigue of martensite-bainite dual phase structure in 65Cr5Mo3W2VSiTi steel
418
Fatigue Abstracts
nitriding reduced the impact fatigue life to about one tenth of that of the same steel without nitriding. The reduction ratio became smaller (approx 1/3) in the case of the high-tension steel with a tensile strength of approx 800 MPa. The impact fatigue strength of nitrided steel is closely related to the impact resistance determined by the Charpy impact test. Graphs, photomicrographs, 11 ref.
Study on the iml~ct fatigue of martensi~,--hainite dual phase structure in 65Cr5Mo3W2VSITi steel Tian, B., Wu, L., Zheng, S., Li, Q., l_d, H. and Yuan, K. Heat Treat. Met. (China) (1995) 7 13-15 (in Chinese) Investigation was carried out on impact fatigue life of 65Cr5Mo3W2VSiTi steel (LM2) with various relative amounts of bainite and martensite tempered at various temperatures. A strengthening-toughening heat tretament process is proposed for cold working dies of LM2 steel against impact fatigue load. Graphs, photomicrographs, 3 ref.
Enhanced fatigue strength of gas nitrocarburized steel by laser heat treatment Fujiki, S. and lsshiki, Y. Tokyo Konye Kaisuz Centa, Kenkyu Hoko (Rep. Tokyo Metrop. Ind. Technol. Cent.) (1995) 24, 25-28 (in Japanese) A CO2 laser is used for further hardening of gas nitrocarburized steel (SCM435). The characteristics of duplex heat treatment (gas nitrocarburizing plus laser heat treatment) and the resulting change in fatigue strength are studied in detail. They are summarized as follows: (1) Surface hardness and hardened depth increase with an increase in the amount of finely structured martensite within the hardened layer. (2) The endurance limit under completely reversed plane bending is considerably enhanced by duplex heat treatment. Graphs, photomicrographs, 10 ref.
Increased life of carburised race car gears by cryogenic treatment Jordine, A. Proc. IMMA Conf. 'The Heat is On!', Melbourne, Victoria, Australia, 24-25 May, 1995, pp. 107-111 Cryogenic treatment is commonly used after heat treatment as a panacea for incomplete transformation of austenite, but there may be reason to consider cryogenic treatment not as a fix for improperly processed parts but as a standard step in the heat treatment process. Treatments on a wide variety of parts (from drill bits to cylinder heads) have been proposed, claiming increased wear resistance and longer service lives. The theory of cryogenic treatment is briefly discussed to support the argument for using cryogenic treatment as part of the heat treating cycle for special cases. Birrana Engineering were interested in the possibilities of increasing wear resistance of gears manufactured for the mining industry. An opportunity arose to rapidly investigate the effect of cryogenic treatment on surface fatigue on carburized gears used in motor racing. This case study discusses carburized En36A first/reverse gear shafts for a Formula Brabham race car run by Birrana Racing. These gear shafts were prone to pitting fatigue failures after a low number of cycles. The addition of a cryogenic treatment to the heat treatment cycle has improved the life of the gears by a considerable margin. The success of this trial has led to cryogenic treatment being applied to gears manufactured for the mining industry. Graphs, 5 ref.
Improvement of tribological properties of boundary layers (Verbesserung der tribologischen Randschicht-eigenschaft durch Nitrocarburieren) Wahl, G. VDI-Z (1995) 137 (l(Spec. lss.)), 56-58, 6 1 ~ 2 (in German) Rising demands on the load-carrying capacity of structural parts cannot always be fully accommodated by the use of suitable materials and optimized designs. For different, often intertwined stress regimes, nitrocarburizing has shown its merit as a boundary layer stabilizer and has thus proved to be a costeffective method of augmenting standard construction and mechanical property parameters. The technology of nitrocarburizing in a salt bath fulfils such key requirements as heat treatment with minimal distortion, environment-friendly processing, and simple, flexible and economical application. The author presents the case for improvements in wear resistance and anti-frictional properties, corrosion resistance, temperature stability and hot strength, fatigue resistance, and anti-scuffing behaviour against rolling motion. The beneficial effects of a modem nitrocarburizing salt system that can be obtained in regard to environmental protection and workplace conditions are given special attention. Graphs, 8 ref.
Residual stress due to welding and its effect on the assessment of cracks near the weld interface Arai, Y., KikuchL M., Watanabe, T. and NakagakL M. Int. J. Pressure Vessels Piping (1995) 63 (3), 237-248 An experimental/analytical hybrid-type investigation of the effects of residual stress on crack propagation due to welding has been performed. The residual stresses in the SAW welded A533B plates and electron beam welded plates, which consist of HT80 and A533B steels, were detected by an acoustoelastic technique. The measured residual stress was incorporated into a finite element procedure, which simulated stable crack growth in IT compact specimens, where the effects on far-field crack parameters were examined. Also investigated was the effect on fatigue crack propagation with the hypothetical residual stress of the identical distribution to that in the electron beam weld. The significance of the residual stress distribution ahead and behind the crack tip in relation to the plastic zone size was identified.
Joint properties of sintered steel parts by laser welding Mural Y. and lsako, H. Kobe Res. Dev. (1995) 45 (1), 49-52 (in Japanese) In the welding of high-carbon sintered steel parts by CO2 laser, it was found that it is possible to prevent defects, such as blowholes, and cold and hot cracking, by applying a filler wire that contains a high amount of manganese, aluminium and titanium when conducting laser welding. The joint strength of sintered material (Fe4).7C-2Cu, Fe-O.9C-3Cu, Fe-0.5C~.Ni-I.5Cu4).5Mo) and sintered material to steel (1055 and 4320) welded by this laser welding technique was investigated. In the tensile tests of these welded joints, the tensile strength of the joint matched the strength of the base metal in postwelding heat treatment. It was also determined that the fatigue properties of joints were improved by post-weld heat treatment. Graphs, photomicrographs, 3 ref.
Mechanical properties of high-temperature brazed titanium materials Lugscheider, E. and Broich, U. Weld. J. 0 9 9 5 ) 74 (5), 169s-176s The mechanical properties of commercial titanium CPTi and Ti-AI6-V4 joints, brazed with Ti-based filler metals in the system Ti(Zr)-Cu-Ni-(Pd), are evaluated by tensile tests at various temperatures, and by fatigue tests at room temperature. The influence of the microstructure in the brazing zone on the mechanical properties of the joints was assessed by conducting metallographic analysis. A vacuum furnace and an induction heating furnace were used for the production of the metallographic and tensile samples. The results from the mechanical and metallographic investigations revealed a strong dependence of the tensile strength of the Ti joints on the microstructure of the brazing zone. The presence of the brittle intermetallic Ti-Cu and Ti-Ni phases in the brazing zone leads to the weakening of the joint. However, the formation of these intermetallic phases can be avoided by using adequate brazing process parameters and by optimizing the joint clearance. In that case, it is possible to fabricate Ti joints with Ti-based filler metals that have excellent mechanical properties, comparable with those of the base metal. Graphs, photomicrographs, II ref.
Study on influences of machining method and surface roughness on pitting of thermally refined steel rollers. IV. In the case of rollers with axial tool marks mating with cylindrically ground roller Yoshidu, A. and Konishi, D. Toraibojisto (J. Jpn. Soc. Tribol.) (1995) 40 (5), 409~,16 (in Japanese) A rolling fatigue test was conducted on a quenched and tempered $45C (carbon steel with 0.45% C) roller with axial tool marks against a cylindrically ground test roller, Results were compared with a former investigation using a roller with circumferential tool marks. Machining of a roller with circumferential tool marks improved the strength to pitting. It is suggested that the improvement in surface roughness has possibilities to be capable of bearing higher load. Photomicrographs, 12 ref.
A simulation of the behaviour of multi-surface fatigue cracks in type 304 stainless steel plate Suh, C.M., Yoon, K.B. and Hwang, N.S. Fatigue Fract. Eng. Muter. Struct. (1995) 18 (4), 515 525 Fatigue tests were carried out to study the growth and coalescence behaviour of multi-surface cracks, which were initiated at semicircular surface notches, and an existing crack growth simulation program was developed to predict and compare with the experimental results. Additional comparisons with ASME and BSI conditions were also carried out to enhance the reliance and integrity of structures and machine elements. The results presented in this paper show that the simulation procedure has utility for fatigue life prediction. Graphs, photomicrographs, 20 ref.
CAFE-a computer program for assessment of structural fatigue [CAFEEin Programmsystem zur Beurteilung der Betriebsfestigkeit] Kottgen, V.G. and Seeger, T Materialpri~fung (June 1995) 37 (6), 244-248 (in German) The paper deals with the computer program system CAFE, which offers some extensions and improvements of methods for analysis of structural fatigue. The largely uniform presentation of test and computation results as well as the analysis of structural fatigue for multiaxial non-proportional load time histories are enabled, and damage parameters modelling the effect of sequence are introduced.
Dimensioning of car coil springs under the aspect of structural fatigue [PKW-Scheaubenfedern: Auslegung aus der Sicht der Betriebsfestigkeit] Schnattinger, H. and Beste, A. Materialpriifung (June 1995) 37 (6), 239-242 (in English and German) One of the unavoidable parts of the suspension is the springs. The durability of these parts depends on the load spectra as well as on the conditions of corrosion. Based on calculations and measurements a so-called dimensioning collective was derived, which represents the summation of loads during the vehicle life. The strength of the springs under different coatings was determined by single- and multi-stage tests in the laboratory. By combining these results it is possible to dimension springs more realistically and to save weight and money.
Fatigue Abstracts
nitriding reduced the impact fatigue life to about one tenth of that of the same steel without nitriding. The reduction ratio became smaller (approx 1/3) in the case of the high-tension steel with a tensile strength of approx 800 MPa. The impact fatigue strength of nitrided steel is closely related to the impact resistance determined by the Charpy impact test. Graphs, photomicrographs, 11 ref.
Study on the iml~ct fatigue of martensi~,--hainite dual phase structure in 65Cr5Mo3W2VSITi steel Tian, B., Wu, L., Zheng, S., Li, Q., l_d, H. and Yuan, K. Heat Treat. Met. (China) (1995) 7 13-15 (in Chinese) Investigation was carried out on impact fatigue life of 65Cr5Mo3W2VSiTi steel (LM2) with various relative amounts of bainite and martensite tempered at various temperatures. A strengthening-toughening heat tretament process is proposed for cold working dies of LM2 steel against impact fatigue load. Graphs, photomicrographs, 3 ref.
Enhanced fatigue strength of gas nitrocarburized steel by laser heat treatment Fujiki, S. and lsshiki, Y. Tokyo Konye Kaisuz Centa, Kenkyu Hoko (Rep. Tokyo Metrop. Ind. Technol. Cent.) (1995) 24, 25-28 (in Japanese) A CO2 laser is used for further hardening of gas nitrocarburized steel (SCM435). The characteristics of duplex heat treatment (gas nitrocarburizing plus laser heat treatment) and the resulting change in fatigue strength are studied in detail. They are summarized as follows: (1) Surface hardness and hardened depth increase with an increase in the amount of finely structured martensite within the hardened layer. (2) The endurance limit under completely reversed plane bending is considerably enhanced by duplex heat treatment. Graphs, photomicrographs, 10 ref.
Increased life of carburised race car gears by cryogenic treatment Jordine, A. Proc. IMMA Conf. 'The Heat is On!', Melbourne, Victoria, Australia, 24-25 May, 1995, pp. 107-111 Cryogenic treatment is commonly used after heat treatment as a panacea for incomplete transformation of austenite, but there may be reason to consider cryogenic treatment not as a fix for improperly processed parts but as a standard step in the heat treatment process. Treatments on a wide variety of parts (from drill bits to cylinder heads) have been proposed, claiming increased wear resistance and longer service lives. The theory of cryogenic treatment is briefly discussed to support the argument for using cryogenic treatment as part of the heat treating cycle for special cases. Birrana Engineering were interested in the possibilities of increasing wear resistance of gears manufactured for the mining industry. An opportunity arose to rapidly investigate the effect of cryogenic treatment on surface fatigue on carburized gears used in motor racing. This case study discusses carburized En36A first/reverse gear shafts for a Formula Brabham race car run by Birrana Racing. These gear shafts were prone to pitting fatigue failures after a low number of cycles. The addition of a cryogenic treatment to the heat treatment cycle has improved the life of the gears by a considerable margin. The success of this trial has led to cryogenic treatment being applied to gears manufactured for the mining industry. Graphs, 5 ref.
Improvement of tribological properties of boundary layers (Verbesserung der tribologischen Randschicht-eigenschaft durch Nitrocarburieren) Wahl, G. VDI-Z (1995) 137 (l(Spec. lss.)), 56-58, 6 1 ~ 2 (in German) Rising demands on the load-carrying capacity of structural parts cannot always be fully accommodated by the use of suitable materials and optimized designs. For different, often intertwined stress regimes, nitrocarburizing has shown its merit as a boundary layer stabilizer and has thus proved to be a costeffective method of augmenting standard construction and mechanical property parameters. The technology of nitrocarburizing in a salt bath fulfils such key requirements as heat treatment with minimal distortion, environment-friendly processing, and simple, flexible and economical application. The author presents the case for improvements in wear resistance and anti-frictional properties, corrosion resistance, temperature stability and hot strength, fatigue resistance, and anti-scuffing behaviour against rolling motion. The beneficial effects of a modem nitrocarburizing salt system that can be obtained in regard to environmental protection and workplace conditions are given special attention. Graphs, 8 ref.
Residual stress due to welding and its effect on the assessment of cracks near the weld interface Arai, Y., KikuchL M., Watanabe, T. and NakagakL M. Int. J. Pressure Vessels Piping (1995) 63 (3), 237-248 An experimental/analytical hybrid-type investigation of the effects of residual stress on crack propagation due to welding has been performed. The residual stresses in the SAW welded A533B plates and electron beam welded plates, which consist of HT80 and A533B steels, were detected by an acoustoelastic technique. The measured residual stress was incorporated into a finite element procedure, which simulated stable crack growth in IT compact specimens, where the effects on far-field crack parameters were examined. Also investigated was the effect on fatigue crack propagation with the hypothetical residual stress of the identical distribution to that in the electron beam weld. The significance of the residual stress distribution ahead and behind the crack tip in relation to the plastic zone size was identified.
Joint properties of sintered steel parts by laser welding Mural Y. and lsako, H. Kobe Res. Dev. (1995) 45 (1), 49-52 (in Japanese) In the welding of high-carbon sintered steel parts by CO2 laser, it was found that it is possible to prevent defects, such as blowholes, and cold and hot cracking, by applying a filler wire that contains a high amount of manganese, aluminium and titanium when conducting laser welding. The joint strength of sintered material (Fe4).7C-2Cu, Fe-O.9C-3Cu, Fe-0.5C~.Ni-I.5Cu4).5Mo) and sintered material to steel (1055 and 4320) welded by this laser welding technique was investigated. In the tensile tests of these welded joints, the tensile strength of the joint matched the strength of the base metal in postwelding heat treatment. It was also determined that the fatigue properties of joints were improved by post-weld heat treatment. Graphs, photomicrographs, 3 ref.
Mechanical properties of high-temperature brazed titanium materials Lugscheider, E. and Broich, U. Weld. J. 0 9 9 5 ) 74 (5), 169s-176s The mechanical properties of commercial titanium CPTi and Ti-AI6-V4 joints, brazed with Ti-based filler metals in the system Ti(Zr)-Cu-Ni-(Pd), are evaluated by tensile tests at various temperatures, and by fatigue tests at room temperature. The influence of the microstructure in the brazing zone on the mechanical properties of the joints was assessed by conducting metallographic analysis. A vacuum furnace and an induction heating furnace were used for the production of the metallographic and tensile samples. The results from the mechanical and metallographic investigations revealed a strong dependence of the tensile strength of the Ti joints on the microstructure of the brazing zone. The presence of the brittle intermetallic Ti-Cu and Ti-Ni phases in the brazing zone leads to the weakening of the joint. However, the formation of these intermetallic phases can be avoided by using adequate brazing process parameters and by optimizing the joint clearance. In that case, it is possible to fabricate Ti joints with Ti-based filler metals that have excellent mechanical properties, comparable with those of the base metal. Graphs, photomicrographs, II ref.
Study on influences of machining method and surface roughness on pitting of thermally refined steel rollers. IV. In the case of rollers with axial tool marks mating with cylindrically ground roller Yoshidu, A. and Konishi, D. Toraibojisto (J. Jpn. Soc. Tribol.) (1995) 40 (5), 409~,16 (in Japanese) A rolling fatigue test was conducted on a quenched and tempered $45C (carbon steel with 0.45% C) roller with axial tool marks against a cylindrically ground test roller, Results were compared with a former investigation using a roller with circumferential tool marks. Machining of a roller with circumferential tool marks improved the strength to pitting. It is suggested that the improvement in surface roughness has possibilities to be capable of bearing higher load. Photomicrographs, 12 ref.
A simulation of the behaviour of multi-surface fatigue cracks in type 304 stainless steel plate Suh, C.M., Yoon, K.B. and Hwang, N.S. Fatigue Fract. Eng. Muter. Struct. (1995) 18 (4), 515 525 Fatigue tests were carried out to study the growth and coalescence behaviour of multi-surface cracks, which were initiated at semicircular surface notches, and an existing crack growth simulation program was developed to predict and compare with the experimental results. Additional comparisons with ASME and BSI conditions were also carried out to enhance the reliance and integrity of structures and machine elements. The results presented in this paper show that the simulation procedure has utility for fatigue life prediction. Graphs, photomicrographs, 20 ref.
CAFE-a computer program for assessment of structural fatigue [CAFEEin Programmsystem zur Beurteilung der Betriebsfestigkeit] Kottgen, V.G. and Seeger, T Materialpri~fung (June 1995) 37 (6), 244-248 (in German) The paper deals with the computer program system CAFE, which offers some extensions and improvements of methods for analysis of structural fatigue. The largely uniform presentation of test and computation results as well as the analysis of structural fatigue for multiaxial non-proportional load time histories are enabled, and damage parameters modelling the effect of sequence are introduced.
Dimensioning of car coil springs under the aspect of structural fatigue [PKW-Scheaubenfedern: Auslegung aus der Sicht der Betriebsfestigkeit] Schnattinger, H. and Beste, A. Materialpriifung (June 1995) 37 (6), 239-242 (in English and German) One of the unavoidable parts of the suspension is the springs. The durability of these parts depends on the load spectra as well as on the conditions of corrosion. Based on calculations and measurements a so-called dimensioning collective was derived, which represents the summation of loads during the vehicle life. The strength of the springs under different coatings was determined by single- and multi-stage tests in the laboratory. By combining these results it is possible to dimension springs more realistically and to save weight and money.