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Assessing the working strength of welded joints in the manufacture of agricultural machinery
that materials for such applications be properly chsrscterized for use in severe conditions. Flat subsize specimens 0.1 in (2.5 mm) thick Wore ground on • surface grinding machine equipped with a variable-speed motor at speeds of 10-30 m s -1 using SiC wheals of grit sizes 60-120. The grinding parameters used in this investigation were chosen from a separate study. The ground specimens were then fatigued at a ealocted stress and the resulting lives were compared with that of the virgin materiel. The surfaces of the specimens were examined under a scanning electron microscope and the roughness and hardness were measured using a standard profilomater and microherdnees tester, rsepectively. The fatigue life of the ground specimens was found to decrease with en increase in speed for both dry and wet conditions. For both the gdt sizes, the fatigue life was lower than that of the virgin material for the dry condition. The fatigue life of specimens ground under wet conditions showed a significant increase at the wheal speed of 10 m s -1 for both gdt sizes, and therafter decreased with increase in speed to below that of the virgin material. The results of the investigation are explained using profilomatry, microhardnesa measurements and scanning electron microscopic examination. Graphs, photomicrographs. 23 refs. Hydrogen s u l p h ~ e
corrosive metabolite. Edyvean, R.G.J.
Int. BiodeteHoration 1991 27, (2), 109-120
A brief overview of the effects of hydrogen sulphide on marine corrosion is given. It draws on both the microbial corrosion literature and the metallurgical fatigue and fracture literature to bring together the various effects of hydrogen sulphide including toxicity and deterioration in product quality, and surface corrosion and streas/fatigue-corrosion interactions. The latter are seldom considered in studies of microbial corrosion but are the prime failure modes on offshore structures. Graphs. 29 refs.
in the US. The standard was first adopted in 1977 for LCF testing at room temperature and was modified in 1980 to include high-temperature tasting prectioss. Current activity within ASTM is aimed at extlmdlng the E606-80 recommended practices to LCF under thermomachenical conditions, LCF in high-preesure hydrogen and the LCF of metal-matrix composite materials. Intarleboratory testing programmes conducted to generate a technical base for modifying E606-80for the aforementioned LCF test types ere discussed. Tests on RQC100, 316 ateals, alloy 800H and Haynes 188 were performed. Graphs. 8 refs. The effect of t h e ageing condition on the fatigue beheviour of e l u m l n l u m - l i t h i u m a l l o y ¢ Tokaji, K., Ogawa, 7". and Fujimura, M. J. Soc. Mater. Sci., Japan Apr. 1991 40, 444-450 (in Japanese) The tensile properties and fatigue beheviour under rotating-banding conditions were inveatigaed for both undereged and averaged specimens of two AI-Li alloys, 2090 and 8090. The results were compared with those of the paak-aged specimens of the same materials and conventional AI alloys, 2024 and 7075, obtained in a previous report. The metastable 8'-phase precipitated and grew during ageing and the diameters of the particles were approximately 10, 20 and 30 nm for the underaged, peek-aged and averaged conditions, respectively. The elongation of the undernged end overnged specimens increased slightly compared with that of the peak-aged specimens, while the proof stress and tensile strength decreased. The fatigue strength was decreased by the underaging and overnging processes. This was due to the decrease in both crack initiation and grov~h resistances. The crack initiation and growth were discussed based on the observation of precipitation of the 8'-phase during ageing. Graphs, photomicrographs. 18 refs. D e v e l o p m e n t of hast-resistant cast steel f o r exhaust manifolds. Ike, M.,
Lorelized corrosion in copper tubes and t h e effect of anti-tarnishing
~ . Notoya, 7". J. Mater. Sci. Lett. Apr. 1991 10, (7), 389-391
Localized corrosion with an 'ant nest' morphology was studied on untreated end tarniah-resistant-treatad Cu tubes. The treated tubas suffered Worse corrosion, which is believed to be the result of the formation of large cathodic areas caused by the treatment leaving anode areas to be attacked. Thin water layers appear to aggravate the problem. Formic acid is believed to be formed by the reaction and causes the problem. Photomicrographs. 6 refs. Corrosion and mechanical propertios X18CrMoVNb 12 1 In f l o w i n g Pb-17U.
of
the
mertensitic
steel
Borgstedt, H.U., Frees, G.,
Grundmann, M. and Peric, Z. Fusion Eng. Design Apr. 1991 14, ( 3 - 4 ) , 329-334
Corrosion, creep-rupture and low-cycle fatigue tests were performed with specimens fabricated of the mertansitic steel X18CrMoVNb 12 1 1.4914 (MANET) in liquid Pb-17Li medium st temperatures in the range 500-550 °C. The corrosion beheviour was studied in the pumped Pb-17Li loop 'PICOLO' at the two temperatures and a flow velocity of 0.30 m a-1, A ready state corrosion rate was observed after an initial period of 1000-2000 h. The corrosion did not show a uniform distribution over the surface of the specimens. The mechanical tests were made in the stagnant liquid Pb-17Li. Creep-rupture teats showed an influence of the liquid metal in long lasting tests only. The ductile bahaviour of the steel and the metallurgical examinations indicated that the effect of Pb-17Li was a corrosion phenomenon. Low-cycle fatigue tests in Pb-17Li resulted in a longer fatigue life than in air. However, a pre-exposuro of the specimens in Pb-17Li changed this beneficial effect. Thus, corrosion may also influence the fatigue life of the steal in Pb-17Li, if the contact of the specimens with the liquid alloy lasts long enough. Wetting by the liquid metal is a necessary condition for its corrosive action and its influence on the mechanical properties. Graphs, photomicrographs. 15 refs. Failure of a l o c o m o t i v e axle---mntellogrephic investigation. Sinha, AN.,
Halder, B.N. and Mohanty, O.N. Welding J. Apr. 1991 70, (4), 59-61
The analysis of an ASTM A21-78 steel axle failure showed that the fatigue cracks originated in the weld deposits used to build up the undersized axle diameter. Hardness testing showed the welded area to be harder than the base metal (300 against 180 Vickers HN). Also, X-ray diffraction showed high tensile residual stresses. In addition, the weld metal had an elevated hydrogen level (2-3 ppm H against less than 1 ppm H in the base metal). Matanogrsphy showed fatigue cracks in the weld rectal, along with a course cast structure. Photomicrographs, 4 raft;. D e v e l o p m e n t of a m e t h o d o l o g y f o r qualifying cafnty-criticel A286
threaded fasteners. Hsieh, C., l.[endrickson, J. and Bamford, R. ASTMJ. Test. Eval. Mar. 1991 19 (2), 136-148
Non-destructive inspection and proof testing ere the principal flaw screening methods used to ensure the integrity of fracture-critical fasteners. However, because of the limitations of various non-deatructive inspection methods and the simplicity of the proof test, the latter method has been identified as a preferred method for the flaw screening of fasteners. A test programme was initiated at the Jet Propulsion Laboratory to determine experimentally the cyclic fatigue life of prscrscked A,?.86 stainless-stsel fasteners that just survived a proof test to a prescribed fraction of their ultimate tensile strength. The functional dependence of the cyclic fatigue life of a fastener on the fatigue stress (mean end alternating stresses), fastener size. material tensile strength and proof load was formulated using the NASA/FLAGRO computer programme. It was found that the proof load has the strongest effect on the fatigue life, while the mean stress has the least effect. The fastener size only has a minor effect, but the alternating stress range has a strong influence on the fatigue life of fasteners. Limited experimental verification of the hypothesized functional relationship is provided in this programme for the effect of proof load and fastener size in addition to the analytic verification. Graphs, photomicrographs. 11 rofs. Current activities in standardization of high-temperature, low-cyclefatigue testing technkluea in t h e United States. Verilli, M.J., Ellis, J.R.
a n d Swindeman, R.W. NASA Technical Memorandum Report No NASA TM-I03675 1991 20 pp
The American Society for Testing and Materials (ASTM) standard E606-80 is the most often used recommended testing practice for low-cycle-fatigue (LCF) testing
64
Akiyama, K., Ohtsuka, K. and Itoh, K. JSAE Rev. Oct. 1990 11, (4), 82-90
A new hnst-reaistant cast steel developed for application to exhaust manifolds is premented, increased exhaust gas temperatures accompanying recent trends towards leaner combustion end higher engine output have pisced a severe thermal load on the exhaust manifold and turbocherger housing. The new cast steal displays better thermal fatigue resistance and oxidation resistance than convantionsi ductile cast irons (DCl) and better cost performance than Ni-resist (ASTM A439 austenitic ductile cast irons). In the materiel design process, the properties required of the material were determined on the basis of statistical analyses. An experiment was then conducted using s test specimen that partially modelled an actual exhaust manifold, and a heating simulation was carried out separately from the engine using an exhaust system simulator. Finally, an endurance test was conducted on an actual exhaust manifold made of the new cast steal using a production engine. Graphs, photomicrographs. 7 refs.
Joining
Rationalization of steel structure w e l d i n g f o r buildings in ,Japan. Mechanical behaviour of beam-to-column w e l d e d j o i n t s w i t h o u t beam
scallops. Yabe, Y. and Sakamoto, S. Shimlzu Tech. Res. Bull. Mar. 1991 (10), 13-19
The majority of buildings having more than three stories in Japan are constructed of • steel structure, instead of the conventional reinforced-concrate structure. However, the number of skirled labourers able to work with steel structures has recently become insufficient. In addition, the cost of steal fabrication has considerably risen. This makes rationalization of steel structures all the more urgently required. The cost ratio of welding to the entire steel construction cost is also quite high. in the design stage consideration of the datails of welded joints is necessary on the basis of the required mechanical performance of the structure. On the other hand, in the fabrication stage, highly efficient welding methods or welding robots are needed to save labour. In this paper an outline is presented of the rationalization of steal structures in Japan. As an example, s welding method that does not use scallops in beam-to-column connections is described in the light of the experimental results, Graphs, 9 refs, Effect of internal defects on the d y n a m i c fatigue strength beheviour of ~ i c t l o n - w e l d e d joints. Meyer, D., Schober, D. and Seifer~, H. Schweissen Schneiden Jan. 1991 (1), 26-28 (in German) The effect of internal defects on the fatigue bahaviour of friction-welded joints with an alternsting torsion load is investigated. To that end specimens of St52-3 and 42CrMo4 with defined and rsproduosable defects are tested. Recommendations for the extension of the calculation code for frictionowelded joints are derived from the experimental findings. (in English p. E26-E28.) Graphs. 6 refs. Influence of transverse vibrations on the fatigue sUength of spotw e l d e d tensile-shear specimens. Press, H. and Simon, G. Schweissen Schnsiden Jan. 1991 (1), 9 - 1 3 (in German) The influence of transverse vibrations on the fatigue strength of a spot-welded tensile-shear specimen (St1403) is determined. The investigations are carried out on two test machines with different types of system (ssrvohydraulic or mechanical) for generating vibrations. It is found that the clamping of the specimen can greatly influence the results of the fatigue strength tests. It is recommended that transverse vibration dampers always be used. (In English p. E2-E4). Graphs. Assessing t h e w o r k i n g strength of w e l d e d joints in t h e manufacture of agricultural machinery. CotTin, D. Schweissen Schnsiden Feb. 1991 (2), 98-102 (in Germanl After describing the fundamentals of the analytical assessment of the working strength of welded joints, working life curves are developed for the latter, particularly for a standard population system for agricultural machinery manufacture. By way of confirmation of the equations derived, single and eight-stage randomized block tests on St52 welds were carried out. The proposed method of calculation is compared with the working life calculation based on the cumulative defect hypotheses. (In English p. E36--E38). Graphs. 13 refs.
Int J Fatigue January 1992
corrosive metabolite. Edyvean, R.G.J.
Int. BiodeteHoration 1991 27, (2), 109-120
A brief overview of the effects of hydrogen sulphide on marine corrosion is given. It draws on both the microbial corrosion literature and the metallurgical fatigue and fracture literature to bring together the various effects of hydrogen sulphide including toxicity and deterioration in product quality, and surface corrosion and streas/fatigue-corrosion interactions. The latter are seldom considered in studies of microbial corrosion but are the prime failure modes on offshore structures. Graphs. 29 refs.
in the US. The standard was first adopted in 1977 for LCF testing at room temperature and was modified in 1980 to include high-temperature tasting prectioss. Current activity within ASTM is aimed at extlmdlng the E606-80 recommended practices to LCF under thermomachenical conditions, LCF in high-preesure hydrogen and the LCF of metal-matrix composite materials. Intarleboratory testing programmes conducted to generate a technical base for modifying E606-80for the aforementioned LCF test types ere discussed. Tests on RQC100, 316 ateals, alloy 800H and Haynes 188 were performed. Graphs. 8 refs. The effect of t h e ageing condition on the fatigue beheviour of e l u m l n l u m - l i t h i u m a l l o y ¢ Tokaji, K., Ogawa, 7". and Fujimura, M. J. Soc. Mater. Sci., Japan Apr. 1991 40, 444-450 (in Japanese) The tensile properties and fatigue beheviour under rotating-banding conditions were inveatigaed for both undereged and averaged specimens of two AI-Li alloys, 2090 and 8090. The results were compared with those of the paak-aged specimens of the same materials and conventional AI alloys, 2024 and 7075, obtained in a previous report. The metastable 8'-phase precipitated and grew during ageing and the diameters of the particles were approximately 10, 20 and 30 nm for the underaged, peek-aged and averaged conditions, respectively. The elongation of the undernged end overnged specimens increased slightly compared with that of the peak-aged specimens, while the proof stress and tensile strength decreased. The fatigue strength was decreased by the underaging and overnging processes. This was due to the decrease in both crack initiation and grov~h resistances. The crack initiation and growth were discussed based on the observation of precipitation of the 8'-phase during ageing. Graphs, photomicrographs. 18 refs. D e v e l o p m e n t of hast-resistant cast steel f o r exhaust manifolds. Ike, M.,
Lorelized corrosion in copper tubes and t h e effect of anti-tarnishing
~ . Notoya, 7". J. Mater. Sci. Lett. Apr. 1991 10, (7), 389-391
Localized corrosion with an 'ant nest' morphology was studied on untreated end tarniah-resistant-treatad Cu tubes. The treated tubas suffered Worse corrosion, which is believed to be the result of the formation of large cathodic areas caused by the treatment leaving anode areas to be attacked. Thin water layers appear to aggravate the problem. Formic acid is believed to be formed by the reaction and causes the problem. Photomicrographs. 6 refs. Corrosion and mechanical propertios X18CrMoVNb 12 1 In f l o w i n g Pb-17U.
of
the
mertensitic
steel
Borgstedt, H.U., Frees, G.,
Grundmann, M. and Peric, Z. Fusion Eng. Design Apr. 1991 14, ( 3 - 4 ) , 329-334
Corrosion, creep-rupture and low-cycle fatigue tests were performed with specimens fabricated of the mertansitic steel X18CrMoVNb 12 1 1.4914 (MANET) in liquid Pb-17Li medium st temperatures in the range 500-550 °C. The corrosion beheviour was studied in the pumped Pb-17Li loop 'PICOLO' at the two temperatures and a flow velocity of 0.30 m a-1, A ready state corrosion rate was observed after an initial period of 1000-2000 h. The corrosion did not show a uniform distribution over the surface of the specimens. The mechanical tests were made in the stagnant liquid Pb-17Li. Creep-rupture teats showed an influence of the liquid metal in long lasting tests only. The ductile bahaviour of the steel and the metallurgical examinations indicated that the effect of Pb-17Li was a corrosion phenomenon. Low-cycle fatigue tests in Pb-17Li resulted in a longer fatigue life than in air. However, a pre-exposuro of the specimens in Pb-17Li changed this beneficial effect. Thus, corrosion may also influence the fatigue life of the steal in Pb-17Li, if the contact of the specimens with the liquid alloy lasts long enough. Wetting by the liquid metal is a necessary condition for its corrosive action and its influence on the mechanical properties. Graphs, photomicrographs. 15 refs. Failure of a l o c o m o t i v e axle---mntellogrephic investigation. Sinha, AN.,
Halder, B.N. and Mohanty, O.N. Welding J. Apr. 1991 70, (4), 59-61
The analysis of an ASTM A21-78 steel axle failure showed that the fatigue cracks originated in the weld deposits used to build up the undersized axle diameter. Hardness testing showed the welded area to be harder than the base metal (300 against 180 Vickers HN). Also, X-ray diffraction showed high tensile residual stresses. In addition, the weld metal had an elevated hydrogen level (2-3 ppm H against less than 1 ppm H in the base metal). Matanogrsphy showed fatigue cracks in the weld rectal, along with a course cast structure. Photomicrographs, 4 raft;. D e v e l o p m e n t of a m e t h o d o l o g y f o r qualifying cafnty-criticel A286
threaded fasteners. Hsieh, C., l.[endrickson, J. and Bamford, R. ASTMJ. Test. Eval. Mar. 1991 19 (2), 136-148
Non-destructive inspection and proof testing ere the principal flaw screening methods used to ensure the integrity of fracture-critical fasteners. However, because of the limitations of various non-deatructive inspection methods and the simplicity of the proof test, the latter method has been identified as a preferred method for the flaw screening of fasteners. A test programme was initiated at the Jet Propulsion Laboratory to determine experimentally the cyclic fatigue life of prscrscked A,?.86 stainless-stsel fasteners that just survived a proof test to a prescribed fraction of their ultimate tensile strength. The functional dependence of the cyclic fatigue life of a fastener on the fatigue stress (mean end alternating stresses), fastener size. material tensile strength and proof load was formulated using the NASA/FLAGRO computer programme. It was found that the proof load has the strongest effect on the fatigue life, while the mean stress has the least effect. The fastener size only has a minor effect, but the alternating stress range has a strong influence on the fatigue life of fasteners. Limited experimental verification of the hypothesized functional relationship is provided in this programme for the effect of proof load and fastener size in addition to the analytic verification. Graphs, photomicrographs. 11 rofs. Current activities in standardization of high-temperature, low-cyclefatigue testing technkluea in t h e United States. Verilli, M.J., Ellis, J.R.
a n d Swindeman, R.W. NASA Technical Memorandum Report No NASA TM-I03675 1991 20 pp
The American Society for Testing and Materials (ASTM) standard E606-80 is the most often used recommended testing practice for low-cycle-fatigue (LCF) testing
64
Akiyama, K., Ohtsuka, K. and Itoh, K. JSAE Rev. Oct. 1990 11, (4), 82-90
A new hnst-reaistant cast steel developed for application to exhaust manifolds is premented, increased exhaust gas temperatures accompanying recent trends towards leaner combustion end higher engine output have pisced a severe thermal load on the exhaust manifold and turbocherger housing. The new cast steal displays better thermal fatigue resistance and oxidation resistance than convantionsi ductile cast irons (DCl) and better cost performance than Ni-resist (ASTM A439 austenitic ductile cast irons). In the materiel design process, the properties required of the material were determined on the basis of statistical analyses. An experiment was then conducted using s test specimen that partially modelled an actual exhaust manifold, and a heating simulation was carried out separately from the engine using an exhaust system simulator. Finally, an endurance test was conducted on an actual exhaust manifold made of the new cast steal using a production engine. Graphs, photomicrographs. 7 refs.
Joining
Rationalization of steel structure w e l d i n g f o r buildings in ,Japan. Mechanical behaviour of beam-to-column w e l d e d j o i n t s w i t h o u t beam
scallops. Yabe, Y. and Sakamoto, S. Shimlzu Tech. Res. Bull. Mar. 1991 (10), 13-19
The majority of buildings having more than three stories in Japan are constructed of • steel structure, instead of the conventional reinforced-concrate structure. However, the number of skirled labourers able to work with steel structures has recently become insufficient. In addition, the cost of steal fabrication has considerably risen. This makes rationalization of steel structures all the more urgently required. The cost ratio of welding to the entire steel construction cost is also quite high. in the design stage consideration of the datails of welded joints is necessary on the basis of the required mechanical performance of the structure. On the other hand, in the fabrication stage, highly efficient welding methods or welding robots are needed to save labour. In this paper an outline is presented of the rationalization of steal structures in Japan. As an example, s welding method that does not use scallops in beam-to-column connections is described in the light of the experimental results, Graphs, 9 refs, Effect of internal defects on the d y n a m i c fatigue strength beheviour of ~ i c t l o n - w e l d e d joints. Meyer, D., Schober, D. and Seifer~, H. Schweissen Schneiden Jan. 1991 (1), 26-28 (in German) The effect of internal defects on the fatigue bahaviour of friction-welded joints with an alternsting torsion load is investigated. To that end specimens of St52-3 and 42CrMo4 with defined and rsproduosable defects are tested. Recommendations for the extension of the calculation code for frictionowelded joints are derived from the experimental findings. (in English p. E26-E28.) Graphs. 6 refs. Influence of transverse vibrations on the fatigue sUength of spotw e l d e d tensile-shear specimens. Press, H. and Simon, G. Schweissen Schnsiden Jan. 1991 (1), 9 - 1 3 (in German) The influence of transverse vibrations on the fatigue strength of a spot-welded tensile-shear specimen (St1403) is determined. The investigations are carried out on two test machines with different types of system (ssrvohydraulic or mechanical) for generating vibrations. It is found that the clamping of the specimen can greatly influence the results of the fatigue strength tests. It is recommended that transverse vibration dampers always be used. (In English p. E2-E4). Graphs. Assessing t h e w o r k i n g strength of w e l d e d joints in t h e manufacture of agricultural machinery. CotTin, D. Schweissen Schnsiden Feb. 1991 (2), 98-102 (in Germanl After describing the fundamentals of the analytical assessment of the working strength of welded joints, working life curves are developed for the latter, particularly for a standard population system for agricultural machinery manufacture. By way of confirmation of the equations derived, single and eight-stage randomized block tests on St52 welds were carried out. The proposed method of calculation is compared with the working life calculation based on the cumulative defect hypotheses. (In English p. E36--E38). Graphs. 13 refs.
Int J Fatigue January 1992