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The influence of manganese sulphide inclusions on environmentally assisted crack growth behaviour: fractographic aspects
The fatigue crack propagation behaviour of commercial steel sheet specimens containing a circular hole. under uniaxial loading condkions at room temperature. was investigated. The experimental data have been analysed in terms of variability of material constants. The results were prawnted in the form of power relationship between the crack growth rate and the stress intensity factor range. 10 refs.
muwmrwnt
of drum
amplitudea in fatigue feiiun
‘MZ%S&$.?~~~~57* Fatigue striation is recognized as one of the features of fatigue failure. By using the tachniques of fatigue crack propagation testing and three-dimensional stress analysis, the loading history of a failed component can be eliminated as long as the relationships among applied stress amplitude. stress intensity rang-s and striation spacing have been established. Knowing the loading history is very helpful to failure analysis and to design improvement of structural components. Application of the above knowledge to the studies of two comer crack problems is presented. Material examined was 403 stainless steel. Besides fractographic analysis. the stress amplitudes were also calculated and compared with the results from fracture surface analysis. 16 refs.
9anding fatipuo of butt weided joints. Guha, B., Path& RadhekrWlnan, ml. Joining Matm Oct. 1999,l (4). 184R-186R
The& A@.
impact on fatigue fracture of carbon spring lE&
A method is described for estimating the fatigue life of adhesively bonded lap joints on the basis of the stress analysis in adhesive layer with finite element method. First. cvcllc tensile fatigue tests were conducted for adhesively bonded lap joints with different lap length and adhesive layer thickness. The results were evaluated from the viewpoint of the maximum values of both tensile and shear stress obtained numerically. instead of the apparent stress. Then these standardized fatigue strengths were compared with those of adhesively bonded bun joints of a thin wall tube (eg S45C) under cyclic tensile and fully reversed torsional load conditions. The results indicate that fatigue strength of lap joints evaluated from the maximum tensile stress of the adhesive layer agrees well with the fatigue strength of adhesively bonded bun joints of thin wall tube under cyclic tensile load condition It is confirmed that fatigue Strength of lap joints can be estimated adequately based on the fatigue strength of the bun joint of thin wall tube and the numerical results for the stress state of adhesive layer. 10 refs.
Fatigue properfir of high-manganese steel at cryogenic temperat;,rea. Muoguchr, T. Yamamoto, S., Shin&a, M., Tsukude, J. and Akanetsu. KobeIco Tech&.
S.D. and
Many welded joints. eg transmission and propeller shafts, and railway track joints, are subjected to bending fatigue loading. Such joints also contain stress raisers and. hence. It is essential to evaluate their fatigue notch strength. Effect of notches on fatigue strength of welded joints has been well documented, but the distinction between a notch and a crack has not been clearly understood. In some instances a notch may be worse than a crack of the same size. and notch root radius plays an important role in determining rhe severity The purpose of this investigation is to understand the role of notches and cracks on fatigue strength of welded joints. with special reference to MMA and MIG/MAG welding.
RamTed
Fatigue life estimation of adhesively bonded lap joints. lmenake, M., Fukuchi, y. and Kishinwto, W J. Eng. Meter. Technol. (Trans. ASME) Oct. 1988,110, (4). 350-354
steel.
Frect. hlech. Oct. 1999,10, (2). 195-171
The influence of repeated impact loading on fatigue fracture of carbon spring En-42J steel was studied. A highly localized plastic deformation was observed at the time of impact The circular disc specimen failed by impact fatigue resulting in small chips and ordinary fatigue failure by slow crack growth. The crack grovvlh behaviour depended on specimen geometry, load spectra and material type. The resultant of applied and residual stress was highest at the edge of the circular disc where the crack initiated. The fractured surface showed typical cleavage facets and dimples indicating acircular martensite. A model is developed to explain fatigue crack initiation and propagation behaviour under impact loadino. Stress calculations are made to determine catastrophic failure. Crack initiation occup&i the major part of impact fatigue life, while crack growth was fast and led quickly to sudden fracture. 10 refs
Resolved shear strasn intensity ccefficient and fatigue crack growth in large crystals. Chen, 0. and Liu, H.W. Theor. A@. Frect. Mech. Oct. 1999,10, (2), 11 l-l 22 Fatigue crack growfh is caused primarily by shear decoheston due to dislocation motion in the crack tip region. The resolved shear stress. which drives dislocation in a crystal. is strongly orientation dependent. and therefore, the cyclic plastic deformation of the shear decohesion process is highly anisotropic. The crack planes are often inclined to the loading axis both in the inplane orientation and in the thickness direction. This inclination induces all three modes of thecrack tip field. K,. K,,and &,, Fatigue crackgrowth in large-grain Al 7029 Al allov was studied The crack tio stress fields of the test swcimens are calculated with the fimte element method The values of K,, 6, and bll are evaluated. The orientation of the crystal at a crack tip was determined with the Laue X-ray method. The crystal orientation and the calculated crack tip stress fields are used to compute the rasolved shear stress intensin, of each of the 12 slip svstems of the crystal at the crack tip. The resolved shear stress field of a slip system is linearly proportional to the resolved shear stress intensitv coefficient. RSSIC. The values of RSSIC thus evaluated are used 1o analvse the orientations of the crack plane and to correlate with the shear fatigue crack growth rate 30 refs
stress
Tha infiuonca of mangana8e ruiphide inclusions on lnvironmentaiiy ic aspects. Bulloch, J./f. as&ted crack growth bahaviour: tract Theor. A&. Frect. Mech. Oct. 1999.10. (2).o%!z! The effects of sulphide non-metalhc inclusion clusters on triggering off some enwonmental crack growth (EAC) processes in low alloy ferritic steels subjected to fatigue in pressurized water reactor (PWR) enviroments have bean fractographically assessed. It is suggested that an incubation period is required for dissolution of manganese sulphide inclusions. ie the attainment of some critical level of sulphur species that initiates the EAC growth process from a discrete inclusion is required. Finally, it has been shown that large crack tip deflections, up to 0.5 m. are common during fatigue crack extension in low alloy ferrite s@als that contain discrete inclusion clusters 9 refs
Multiaxial fatigue life predictions under the influence of mean stresses. Fetemi, Aand Kureth, P. J. Eng. A&m. Technol. (Tlens. ASME) Oct. 1999.110, (4). 390-399 Two materials, an lnconel 716 and a 1045 steel, are used to verify the extension of a shear strain-based parameter developed to account for out-of-phase cyclic strain hardening to multiaxial mean stresses. Shear strain amplitude on the maximum shear strain amplitude plane and the maximum stress normal to this plane are the normal stress-strain parameters considered in this approach. Tensiorctorsion and axial-internal pressure loadings using tubular specimens are employed to investigate stressstrain states that exhibit mean strains and/or mean stresses. Deformation response relevant to the proposed fatigue damage algorithm such as mean stress relaxation is discussed Adequate fatigue life correlations are obtained by implementing the proposed analysis. It is also demonstrated that methodologies successful for correlating uniaxial mean stress data often lead to errowous multiaxial life oredictions. 34 refs.
Rev. Aug. 1988,
(4). 31-34
Low cycle and high cycle fatigue behaviours of high Mn steels 22Mc-13Cr-5Ni and SS304LN for cwwenic use were investiaated. Strain rate dependence of cyclic deformation and low cycle iat&e life was studied Effect of stress con&?ntration on ;he tempersturefatigue strength relation was discussed 12 refs.
Fatigue strength analysis of parallel wire strand cables based on statistical theory of extromue. ii. Matsukawe,A., Kamei, M.. Mizoguchi T and Sasaki, Y Stahlbau, July 1999,57, (7). 205210 Design 6N curves of parallel wire strand cables are obtained by an approach based on the Statistical theory of extremes. Wire length. wire diameter, the number of wires and mean stress are assumed to be the important factors affecting fatigue strength of such strands The effects of those factors were investigated experimentally and analytically. The effect of wire length and the number of wires was estimated by using the Weibull distribution based on the statistical theory of extremes, The effect of mean stress can be evaluated by using the equivalent stress range proposed previously. Taking these effects into account. the estimated P-S-N CWJBS are introduced as a function of wire length and the number of wires in the range from 1V to 2 x 10’ fatigue cycles. Lastly. design S-N curves are presented from the results obtained above. 13 refs
The thermal activation energy for fatigue of Fe-lCr-O.SMo. and Gs+rett G. G. Metall. Trans. A Dec. 1999. 19A. (12). 2979-2997
Corrie.M.6.
The temperature dependence of fatigue crack propagation IS considered man Fe-1 Cr-O.SMo alloy steel This material was tested at temperatures between 42%55o’C. a frequency of 1 Hz. and an R-ratio of 0 1 It is shown that the effect of temperature can be explained in terns of a thermal activation energy for fatigue. The magnitude of this activation energy 1s a function of AK and varies from > 150 kJ/mole at 15 MPaflo 30 W/mole above 30 MPaflThe magnitude of these activation energies supports the idea that oxidation. and not creep. IS the rate-controllmg time-dependent process for the test conditions studied 34 refs
Preparation and properties of fine grain beta-CuAiNi strain-memory alloys. Mukunthan, K. and Brown, L.C. Meta//. Trans. A Dec. 1988.1SA, (12). 2921-2929 A method has been developed to produce grain sizes as small as 5 pm in alloys of betaCuAlNi The alloys were of eutectotd composition and a procedure was developed for determinina the comoosition of a eutectold allov hvina any rewired value for transltlon temperat& (&f,) The thermomechanical treatment involved two sequential stages of warm rolhng followed by recrystallization The alloys produced were single-phase beta-type with no second phase being present. Characteristic two-stages StresSstrain curves were obtained for most of the specimens. It was generally found that the tenslIe strength and strain 1o failure increased wth decreawng grain size according to a Hall-Petch tvpe relationship down to a grain size of 5 pm. A fracture strength of 1200 MPa and a fracture stram of 10% were obtained I” the besr alloy It was found that the major recovery mode. whether pseudoelastic or strain-memory. did not have any significant effect on the total recovery obtained Recovery properties were not affected slgnificantlv by decreasing gram we. and 66% recovery could still be obtalned at a grain size of approx 10 pm Grain refinement improved the fatigue life considerably. possibly due lo the high ultimate fracture stress and ductile fracture mode A fatigue life of 275 OCO cycles could be obtamed for an applied stress of 330 MPa and a steady state of strain of 0.7%. At fine-grain sizes most of the fractures were due to transgranular-type brittle fracture and microvoid-type ductile fracture. depending on the alloy composltion. It was suggested that the dfferences between the alloys as due to differences m oxygen segregation at the grain boundaries 37 refs
The effect of microstructure on the fatigue crack growth characteristics of steel in a dry air environment. Bulkxh, J.H. Res. Mech. 1999,24. (3). 295-275 Over the yield strength range 450-1060 MPa (BS 1501 271) the effect of strength level on AKlh was minimal at a R-ratio of 0.66 The effect of microstructure on Ko, and the t,, value to which fast failure occurred. can best be explained in terms of the carbon content of the martensite present in the various microstructures. The onset of stage Ill fatigue for all microstructures was signalled by the appearance of microvoid coalescence on the fatiaue fracture surface. A oranular bainitic microstructure (32% marten&e islands) exhibited a linear effect of R-r&o on AK, which could be described by a simple-equation. Ahh = 7.6 Y 4.8 (R). Growth rate transients were obwved at a AK& level af which the reversed plastic zone size approaches the average austenite grain size. Such growth rate transients are independent of R-ratio and relative humidin/ 6 refs
A stochastic model for fatigue crack propagetion with random propagetion resistance. Iham c. and Misaw8, T. Eng. Frsct. Mech. 1999,3l, (1). 95-104
Int J Fatigue May 1989
muwmrwnt
of drum
amplitudea in fatigue feiiun
‘MZ%S&$.?~~~~57* Fatigue striation is recognized as one of the features of fatigue failure. By using the tachniques of fatigue crack propagation testing and three-dimensional stress analysis, the loading history of a failed component can be eliminated as long as the relationships among applied stress amplitude. stress intensity rang-s and striation spacing have been established. Knowing the loading history is very helpful to failure analysis and to design improvement of structural components. Application of the above knowledge to the studies of two comer crack problems is presented. Material examined was 403 stainless steel. Besides fractographic analysis. the stress amplitudes were also calculated and compared with the results from fracture surface analysis. 16 refs.
9anding fatipuo of butt weided joints. Guha, B., Path& RadhekrWlnan, ml. Joining Matm Oct. 1999,l (4). 184R-186R
The& A@.
impact on fatigue fracture of carbon spring lE&
A method is described for estimating the fatigue life of adhesively bonded lap joints on the basis of the stress analysis in adhesive layer with finite element method. First. cvcllc tensile fatigue tests were conducted for adhesively bonded lap joints with different lap length and adhesive layer thickness. The results were evaluated from the viewpoint of the maximum values of both tensile and shear stress obtained numerically. instead of the apparent stress. Then these standardized fatigue strengths were compared with those of adhesively bonded bun joints of a thin wall tube (eg S45C) under cyclic tensile and fully reversed torsional load conditions. The results indicate that fatigue strength of lap joints evaluated from the maximum tensile stress of the adhesive layer agrees well with the fatigue strength of adhesively bonded bun joints of thin wall tube under cyclic tensile load condition It is confirmed that fatigue Strength of lap joints can be estimated adequately based on the fatigue strength of the bun joint of thin wall tube and the numerical results for the stress state of adhesive layer. 10 refs.
Fatigue properfir of high-manganese steel at cryogenic temperat;,rea. Muoguchr, T. Yamamoto, S., Shin&a, M., Tsukude, J. and Akanetsu. KobeIco Tech&.
S.D. and
Many welded joints. eg transmission and propeller shafts, and railway track joints, are subjected to bending fatigue loading. Such joints also contain stress raisers and. hence. It is essential to evaluate their fatigue notch strength. Effect of notches on fatigue strength of welded joints has been well documented, but the distinction between a notch and a crack has not been clearly understood. In some instances a notch may be worse than a crack of the same size. and notch root radius plays an important role in determining rhe severity The purpose of this investigation is to understand the role of notches and cracks on fatigue strength of welded joints. with special reference to MMA and MIG/MAG welding.
RamTed
Fatigue life estimation of adhesively bonded lap joints. lmenake, M., Fukuchi, y. and Kishinwto, W J. Eng. Meter. Technol. (Trans. ASME) Oct. 1988,110, (4). 350-354
steel.
Frect. hlech. Oct. 1999,10, (2). 195-171
The influence of repeated impact loading on fatigue fracture of carbon spring En-42J steel was studied. A highly localized plastic deformation was observed at the time of impact The circular disc specimen failed by impact fatigue resulting in small chips and ordinary fatigue failure by slow crack growth. The crack grovvlh behaviour depended on specimen geometry, load spectra and material type. The resultant of applied and residual stress was highest at the edge of the circular disc where the crack initiated. The fractured surface showed typical cleavage facets and dimples indicating acircular martensite. A model is developed to explain fatigue crack initiation and propagation behaviour under impact loadino. Stress calculations are made to determine catastrophic failure. Crack initiation occup&i the major part of impact fatigue life, while crack growth was fast and led quickly to sudden fracture. 10 refs
Resolved shear strasn intensity ccefficient and fatigue crack growth in large crystals. Chen, 0. and Liu, H.W. Theor. A@. Frect. Mech. Oct. 1999,10, (2), 11 l-l 22 Fatigue crack growfh is caused primarily by shear decoheston due to dislocation motion in the crack tip region. The resolved shear stress. which drives dislocation in a crystal. is strongly orientation dependent. and therefore, the cyclic plastic deformation of the shear decohesion process is highly anisotropic. The crack planes are often inclined to the loading axis both in the inplane orientation and in the thickness direction. This inclination induces all three modes of thecrack tip field. K,. K,,and &,, Fatigue crackgrowth in large-grain Al 7029 Al allov was studied The crack tio stress fields of the test swcimens are calculated with the fimte element method The values of K,, 6, and bll are evaluated. The orientation of the crystal at a crack tip was determined with the Laue X-ray method. The crystal orientation and the calculated crack tip stress fields are used to compute the rasolved shear stress intensin, of each of the 12 slip svstems of the crystal at the crack tip. The resolved shear stress field of a slip system is linearly proportional to the resolved shear stress intensitv coefficient. RSSIC. The values of RSSIC thus evaluated are used 1o analvse the orientations of the crack plane and to correlate with the shear fatigue crack growth rate 30 refs
stress
Tha infiuonca of mangana8e ruiphide inclusions on lnvironmentaiiy ic aspects. Bulloch, J./f. as&ted crack growth bahaviour: tract Theor. A&. Frect. Mech. Oct. 1999.10. (2).o%!z! The effects of sulphide non-metalhc inclusion clusters on triggering off some enwonmental crack growth (EAC) processes in low alloy ferritic steels subjected to fatigue in pressurized water reactor (PWR) enviroments have bean fractographically assessed. It is suggested that an incubation period is required for dissolution of manganese sulphide inclusions. ie the attainment of some critical level of sulphur species that initiates the EAC growth process from a discrete inclusion is required. Finally, it has been shown that large crack tip deflections, up to 0.5 m. are common during fatigue crack extension in low alloy ferrite s@als that contain discrete inclusion clusters 9 refs
Multiaxial fatigue life predictions under the influence of mean stresses. Fetemi, Aand Kureth, P. J. Eng. A&m. Technol. (Tlens. ASME) Oct. 1999.110, (4). 390-399 Two materials, an lnconel 716 and a 1045 steel, are used to verify the extension of a shear strain-based parameter developed to account for out-of-phase cyclic strain hardening to multiaxial mean stresses. Shear strain amplitude on the maximum shear strain amplitude plane and the maximum stress normal to this plane are the normal stress-strain parameters considered in this approach. Tensiorctorsion and axial-internal pressure loadings using tubular specimens are employed to investigate stressstrain states that exhibit mean strains and/or mean stresses. Deformation response relevant to the proposed fatigue damage algorithm such as mean stress relaxation is discussed Adequate fatigue life correlations are obtained by implementing the proposed analysis. It is also demonstrated that methodologies successful for correlating uniaxial mean stress data often lead to errowous multiaxial life oredictions. 34 refs.
Rev. Aug. 1988,
(4). 31-34
Low cycle and high cycle fatigue behaviours of high Mn steels 22Mc-13Cr-5Ni and SS304LN for cwwenic use were investiaated. Strain rate dependence of cyclic deformation and low cycle iat&e life was studied Effect of stress con&?ntration on ;he tempersturefatigue strength relation was discussed 12 refs.
Fatigue strength analysis of parallel wire strand cables based on statistical theory of extromue. ii. Matsukawe,A., Kamei, M.. Mizoguchi T and Sasaki, Y Stahlbau, July 1999,57, (7). 205210 Design 6N curves of parallel wire strand cables are obtained by an approach based on the Statistical theory of extremes. Wire length. wire diameter, the number of wires and mean stress are assumed to be the important factors affecting fatigue strength of such strands The effects of those factors were investigated experimentally and analytically. The effect of wire length and the number of wires was estimated by using the Weibull distribution based on the statistical theory of extremes, The effect of mean stress can be evaluated by using the equivalent stress range proposed previously. Taking these effects into account. the estimated P-S-N CWJBS are introduced as a function of wire length and the number of wires in the range from 1V to 2 x 10’ fatigue cycles. Lastly. design S-N curves are presented from the results obtained above. 13 refs
The thermal activation energy for fatigue of Fe-lCr-O.SMo. and Gs+rett G. G. Metall. Trans. A Dec. 1999. 19A. (12). 2979-2997
Corrie.M.6.
The temperature dependence of fatigue crack propagation IS considered man Fe-1 Cr-O.SMo alloy steel This material was tested at temperatures between 42%55o’C. a frequency of 1 Hz. and an R-ratio of 0 1 It is shown that the effect of temperature can be explained in terns of a thermal activation energy for fatigue. The magnitude of this activation energy 1s a function of AK and varies from > 150 kJ/mole at 15 MPaflo 30 W/mole above 30 MPaflThe magnitude of these activation energies supports the idea that oxidation. and not creep. IS the rate-controllmg time-dependent process for the test conditions studied 34 refs
Preparation and properties of fine grain beta-CuAiNi strain-memory alloys. Mukunthan, K. and Brown, L.C. Meta//. Trans. A Dec. 1988.1SA, (12). 2921-2929 A method has been developed to produce grain sizes as small as 5 pm in alloys of betaCuAlNi The alloys were of eutectotd composition and a procedure was developed for determinina the comoosition of a eutectold allov hvina any rewired value for transltlon temperat& (&f,) The thermomechanical treatment involved two sequential stages of warm rolhng followed by recrystallization The alloys produced were single-phase beta-type with no second phase being present. Characteristic two-stages StresSstrain curves were obtained for most of the specimens. It was generally found that the tenslIe strength and strain 1o failure increased wth decreawng grain size according to a Hall-Petch tvpe relationship down to a grain size of 5 pm. A fracture strength of 1200 MPa and a fracture stram of 10% were obtained I” the besr alloy It was found that the major recovery mode. whether pseudoelastic or strain-memory. did not have any significant effect on the total recovery obtained Recovery properties were not affected slgnificantlv by decreasing gram we. and 66% recovery could still be obtalned at a grain size of approx 10 pm Grain refinement improved the fatigue life considerably. possibly due lo the high ultimate fracture stress and ductile fracture mode A fatigue life of 275 OCO cycles could be obtamed for an applied stress of 330 MPa and a steady state of strain of 0.7%. At fine-grain sizes most of the fractures were due to transgranular-type brittle fracture and microvoid-type ductile fracture. depending on the alloy composltion. It was suggested that the dfferences between the alloys as due to differences m oxygen segregation at the grain boundaries 37 refs
The effect of microstructure on the fatigue crack growth characteristics of steel in a dry air environment. Bulkxh, J.H. Res. Mech. 1999,24. (3). 295-275 Over the yield strength range 450-1060 MPa (BS 1501 271) the effect of strength level on AKlh was minimal at a R-ratio of 0.66 The effect of microstructure on Ko, and the t,, value to which fast failure occurred. can best be explained in terms of the carbon content of the martensite present in the various microstructures. The onset of stage Ill fatigue for all microstructures was signalled by the appearance of microvoid coalescence on the fatiaue fracture surface. A oranular bainitic microstructure (32% marten&e islands) exhibited a linear effect of R-r&o on AK, which could be described by a simple-equation. Ahh = 7.6 Y 4.8 (R). Growth rate transients were obwved at a AK& level af which the reversed plastic zone size approaches the average austenite grain size. Such growth rate transients are independent of R-ratio and relative humidin/ 6 refs
A stochastic model for fatigue crack propagetion with random propagetion resistance. Iham c. and Misaw8, T. Eng. Frsct. Mech. 1999,3l, (1). 95-104
Int J Fatigue May 1989