- Email: [email protected]
Fatigue properties of electroless deposited steel
Fatigue Fatigue performance of orthotropic steel bridge and consequences for existing bridges. [Ermudungsversuche mit orthotropen Platten und Konsequenzen fur die Beurteihmg hestehender Fahrbahnplatten.]. Cunin,qhome. J.. Kolstein. H. and Poschen, M Stnhlbnu ( 1996) 63 I I ). 452458 Higher wheel loads and increasing traffic intensity mean that bridges are subjected to greater fatigue loading than in the past. This has resulted in the occurrence of fatigue cracks in modern steel bridges within their service lives. Also. detading and fabrication was not always carried out to a sufficiently high standard. Detailed studies of the fatigue design and behavior of steel bridges were required. In particular on the components of orthotropic deck structures. ah the deck is directly subjected to the severe impact of heavy wheel loads. This article reviews the recently undertaken research on welded details of \uch a deck in relation to observed fatigue failures. It highlight\ the practical experience and recommendations on how to reduce the risk of fatigue failures. Graph\. 5 ref
Fatigue strength of riveted connections. Ku/ok. G.L. Stnhlbrru ( 1996) 6% I I ). 445-15 I
Asbstracts riveted steel bridges i\ mentioned and an outlook is given in what way Annex C will be extended to make it applicable to preuure vcuel\ and tanks. Graphs, 26 ref.
Overload retardation effects on stress corrosion behaviour of prestressina steel.
This paper analyses overload retardation effects on stress corrosion cracking (xc) of high-strength pearlitic steel for civil engineering u&e in prestressed concrete. Fatigue pre-cracking load on the samples generates compressive residual stresses m the vicinity of the crack tip which improve the macroscopic see behaviour, delaying either the metal dissolution or the hydrogen entry. thus increasing the fracture load in aggressive environment. Microscopically, compressive residual atresses produce a transition topography between the fatigue pre-crack and the cleavage-like (unstable) fracture mode. Photomicrographs, II ref.
Effect of second phase on the fatigue crack growth in AISI 4340 steel.
New riveted \tructurea generally have not been built in the past several decades. As a consequence, less attention has been paid to their fatigue life behavior than to \tructures containing contemporary fastening elements such as bolts or welds. The behavior of riveted members ih a matter of considerable economic importance to owners and regulatory authorities, however. For example. it is obvious that the life of the large stock of riveted bridges that still exist mu\t be extended. at the same time maintaining a satisfactory level of safety. Evaluation of the remaming fatigue life of a rlveted structure has been impeded by the lack of a reasonable data base of test results of full-sire riveted members. Recent work in both North America and Europe has addressed the need for better fatigue life data for riveted members. The paper reports on the author’\ research and that of others into the fatigue behavior of riveted members. The results of tests on full-size llexural members and axially loaded members are reported, and these teSt results are compared with the design recommendation\ of several European and North American standards. Recommendations arc presented for a fatigue life classification for asse\\ment of riveted shear splices. Graph\, I4 ref.
Probabilistic based evaluation of fatigue safety of existing highway bridges. [Probabilistisch abgesicherter Ermundungsfestigkeitsnachweis fur bestehende Strassenhrucken.]. Geis.\lrr, K. and Grmsr, W. Strrhlbau ( 1996) 6% I I). 437444 A newly developed multi-step method for the evaluation of the remaining fatigue life of steel bridges is diacu\sed. This method is based on the (traditional) damage accumulation concept and the fracture mechanics. The application on exiatmg highway bridges is shown. Basic information about safety theory, in order to define the partial safety factors and the design value>. IS briefly described. Furthermore, the decreasing value of the reliability index beta as a function of time is shown on two examples, a new steel concrete composite bridge and an old riveted steel bridge. Graphs, 8 ref.
Hwm,q, J.-R., Pmg. K.-P. curd Wang, C.-C. Jourmrl nf Matrricdc Sciencr Letters ( 1996) lS(3). 192-l 96 The effect of types and volume fraction of the second phase on the fatigue crack growth rate in AISI 4340 steel was investigated. Three different heat treatment methods were followed to produce second phases of different type\: isothermal heat treatment (IHT). interrupt quench treatment (IQT), and direct quench treatment (DQT). The IHT specimens had a lower bainite second phase. The fatigue crack growth rate for these specimens decreased with increasing time of heat treatment. Thi\ indicated that a greater amount 01 lower bainite enhance, the resistance to fatigue crack growth. Similar relationship between the volamc fraction of martenslte second phase and fatigue crack growth resistance wa\ found for the IQT specimens which showed a highly tempered martensite second phase. The fatigue property of both IHT and IQT specimens was superior to that of the DQT specimen\. A ductile second phase enhanced the fatigue property of AlSl 4340 steel. The higher the volume fraction of ductile second phase, the lower the fatigue crack growth rate. However, the fatigue crack growth resistance of specimen\ with highly trnpered martensite recond phase was superior to that of those with lower bainitc second phase. Graphs, photomlcrographs. 17 ref.
Effects of prestrain on fatigue threshold and initial yield stress of normalized 1035 steel. Luo. J.X. md Ton. Y.X. Amt Metcrlhqyim Sinrco tErrglir/l
Lcttervj
( 1996)
Y(4 1. 247-250
Akesson. B. nnd Edlund B. Stnhlhnu (1996) 6% I I ), 429436
The relationshIps between fatigue threshold AK,,, and the initial yield strength n,, of normali/.ed 1035 steel after various preatrain (at first, second and third hardening stages respectively) were investigated through the analyua of the sigma epsilon curves and transmission electron microscope (TEM). After prestraining at first or second hardening stage, there 1s a marked drop in the values AK,, and CT,,.This is in correspondence with the depinning of the solute atom\ from the d&location lines in the Cottrell atmosphere. At the third hardening stage of prehtrain the fatigue threshold increases rapidly and AK,,, is even I.6 times aa large as the original value. This is because at this stage no dislocation-cell free areas can be found and the refinement of the dislocation cells occurs with the increase in the prestrain level. Graph\. 3 ref
This article presents the results of field investigations of riveted steel railway bridges and a full-scale fatigue test series of riveted members from an old bridge. The main finding is that there might be a substantial remaining fatigue life of riveted railway bridge\ still in u\e today. Graphs, 7 ref
Zhrmg, Y.Z.. Wu, Y. Y. md Ym. M. Joctmrd of Motericrlv .%ieru Lrrtrrs
Remaining fatigue life of riveted railway bridges.
Rating of structural and fatigue safety of old steel bridges by measurement. [Messungen an alteren Stahlbrucken zur Zustandsanalyse und Ermudungsbeurteilung.]. Brmdes, K.. Km~pp. J. mrd Hertrr, Stnhlbnu ( 1996) 6% I I ), 42 I428
J.
When evaluating old steel bridges, very often considerable reserves of the load bearing capacity are discovered. Referring to three examples, a beam grillage of a truss girder bridge. a beam girder bridge and an arch-bridge, it is pre\ented how to solve problems occurring on old steel bridges by measurement. Also, special attention is given to structural effects which can only be discovered by measurement. Graphs, I3 ref.
assessments for the ultimate limit state and fatigue and their relations to the choice of material to avoid brittle fracture. [Die Tragsicherheit, die Ermudeungssicherheit und das Sprodbruchproblem.].
The safety
Sedlucek, G.. Stmn~honrr. N.. Stmrl. Liessrm, A. Stnhlbau ( 1996) 6% I I). 407414
G.. Dnhl.
W., Lnn~enher~,
P
Fatigue properties of electroless deposited steel.
( 1996)
15. I.%& I366
The fatigue properties of 30CrMo steel electroless deposited with Ni-9.5 wt% P were studied by three-point bending fatigue tests. The microstructures before and after fracture were Characterized using SEM and eletron diffraction. The specimens were annealed before fatigue testing. Annealing at 200°C did not change the amorphous structure, but Ni-rich Ni3P crystals were found in specimens annealed at 4OO’C. Annealing at 600°C caused the coarsening of the Ni particle% in Ni3P grains or grain boundaries. The faugue strength decreased from 750 MPa and 460, 360, and 340 MPa upon annealing at 200°C for I h, 400°C for I h, and 600°C for 3 h. respectively. Shot peening before plating increased the fatigue strength of annealed samples. Fatigue striations were found m the fracture face of the coating. This indicated that fatigue crack iniuated at the outer surface of the coatings. Short and Ruvial patterns were also found, indicating a quasi-cleavage fracture. The results indicated that the fatigue properties of this steel coating primarily depend on the fatigue resistance. Photomicrographs, deffraction patterns, I2 ref.
curd
This paper presents the basic philosophy of a new method for the choice of material to avoid brittle fracture laid down in Annex C (1996) to Eurocode 3. This method allows determintion of requirements for the material toughness in the transition temperature range both from ultimate limit state and fatigue requirements and it relates these toughness-requirements to the T27J-values for the Charpy-energy specified in EN 10025, EN 101 I3 and EN 10137. The reliabilty of the method has been proved by calibration to large scale fracture mechanics test results. Comparisons of the requirements of Annex C with upper shelf requirement\ (Aufschweissbiegeversuch) and with a national guideline for the choice of material (DAST-RI 009) have been performed. Also the relationship between the Annex C-requirements and the safety assessment for old
Effect of hard anodize thickness on the fatigue of AA6061 and C355 aluminium. Rnteick. R.G. Jr., BinkoMski. T.C. md Borq B.C.. Journal of Matem& Sciencr Lrttm ( 1996) lS(lS), 1321-1323 The effect of hard anodized coatings of varying thicknesses on the fatigue strength of wrought AA6061 (T6 and T65l) and AA C355.T6 aluminium alloys was studied by producing stress-life (S-IV) curves. Hour-glass shaped specimens were subjected to rotary bend fatigue testing. The hard anodized coating thicknesses were 31-61 Nm. Both HC3 and HC5 coatings reduced the fatigue strength of the AA6061 alloy samples at all lifetimes. The maximum fatigue debit for the axial teats was -I .5 x Ioh - 2.5 x IO’ cycles. On the other hand, the HCS coating did not show significant effect on the fatigue of AA C3SS-T6 in rotary bending tests. Graphs, photomicrographs. 7 ref.
Fatigue strength of riveted connections. Ku/ok. G.L. Stnhlbrru ( 1996) 6% I I ). 445-15 I
Asbstracts riveted steel bridges i\ mentioned and an outlook is given in what way Annex C will be extended to make it applicable to preuure vcuel\ and tanks. Graphs, 26 ref.
Overload retardation effects on stress corrosion behaviour of prestressina steel.
This paper analyses overload retardation effects on stress corrosion cracking (xc) of high-strength pearlitic steel for civil engineering u&e in prestressed concrete. Fatigue pre-cracking load on the samples generates compressive residual stresses m the vicinity of the crack tip which improve the macroscopic see behaviour, delaying either the metal dissolution or the hydrogen entry. thus increasing the fracture load in aggressive environment. Microscopically, compressive residual atresses produce a transition topography between the fatigue pre-crack and the cleavage-like (unstable) fracture mode. Photomicrographs, II ref.
Effect of second phase on the fatigue crack growth in AISI 4340 steel.
New riveted \tructurea generally have not been built in the past several decades. As a consequence, less attention has been paid to their fatigue life behavior than to \tructures containing contemporary fastening elements such as bolts or welds. The behavior of riveted members ih a matter of considerable economic importance to owners and regulatory authorities, however. For example. it is obvious that the life of the large stock of riveted bridges that still exist mu\t be extended. at the same time maintaining a satisfactory level of safety. Evaluation of the remaming fatigue life of a rlveted structure has been impeded by the lack of a reasonable data base of test results of full-sire riveted members. Recent work in both North America and Europe has addressed the need for better fatigue life data for riveted members. The paper reports on the author’\ research and that of others into the fatigue behavior of riveted members. The results of tests on full-size llexural members and axially loaded members are reported, and these teSt results are compared with the design recommendation\ of several European and North American standards. Recommendations arc presented for a fatigue life classification for asse\\ment of riveted shear splices. Graph\, I4 ref.
Probabilistic based evaluation of fatigue safety of existing highway bridges. [Probabilistisch abgesicherter Ermundungsfestigkeitsnachweis fur bestehende Strassenhrucken.]. Geis.\lrr, K. and Grmsr, W. Strrhlbau ( 1996) 6% I I). 437444 A newly developed multi-step method for the evaluation of the remaining fatigue life of steel bridges is diacu\sed. This method is based on the (traditional) damage accumulation concept and the fracture mechanics. The application on exiatmg highway bridges is shown. Basic information about safety theory, in order to define the partial safety factors and the design value>. IS briefly described. Furthermore, the decreasing value of the reliability index beta as a function of time is shown on two examples, a new steel concrete composite bridge and an old riveted steel bridge. Graphs, 8 ref.
Hwm,q, J.-R., Pmg. K.-P. curd Wang, C.-C. Jourmrl nf Matrricdc Sciencr Letters ( 1996) lS(3). 192-l 96 The effect of types and volume fraction of the second phase on the fatigue crack growth rate in AISI 4340 steel was investigated. Three different heat treatment methods were followed to produce second phases of different type\: isothermal heat treatment (IHT). interrupt quench treatment (IQT), and direct quench treatment (DQT). The IHT specimens had a lower bainite second phase. The fatigue crack growth rate for these specimens decreased with increasing time of heat treatment. Thi\ indicated that a greater amount 01 lower bainite enhance, the resistance to fatigue crack growth. Similar relationship between the volamc fraction of martenslte second phase and fatigue crack growth resistance wa\ found for the IQT specimens which showed a highly tempered martensite second phase. The fatigue property of both IHT and IQT specimens was superior to that of the DQT specimen\. A ductile second phase enhanced the fatigue property of AlSl 4340 steel. The higher the volume fraction of ductile second phase, the lower the fatigue crack growth rate. However, the fatigue crack growth resistance of specimen\ with highly trnpered martensite recond phase was superior to that of those with lower bainitc second phase. Graphs, photomlcrographs. 17 ref.
Effects of prestrain on fatigue threshold and initial yield stress of normalized 1035 steel. Luo. J.X. md Ton. Y.X. Amt Metcrlhqyim Sinrco tErrglir/l
Lcttervj
( 1996)
Y(4 1. 247-250
Akesson. B. nnd Edlund B. Stnhlhnu (1996) 6% I I ), 429436
The relationshIps between fatigue threshold AK,,, and the initial yield strength n,, of normali/.ed 1035 steel after various preatrain (at first, second and third hardening stages respectively) were investigated through the analyua of the sigma epsilon curves and transmission electron microscope (TEM). After prestraining at first or second hardening stage, there 1s a marked drop in the values AK,, and CT,,.This is in correspondence with the depinning of the solute atom\ from the d&location lines in the Cottrell atmosphere. At the third hardening stage of prehtrain the fatigue threshold increases rapidly and AK,,, is even I.6 times aa large as the original value. This is because at this stage no dislocation-cell free areas can be found and the refinement of the dislocation cells occurs with the increase in the prestrain level. Graph\. 3 ref
This article presents the results of field investigations of riveted steel railway bridges and a full-scale fatigue test series of riveted members from an old bridge. The main finding is that there might be a substantial remaining fatigue life of riveted railway bridge\ still in u\e today. Graphs, 7 ref
Zhrmg, Y.Z.. Wu, Y. Y. md Ym. M. Joctmrd of Motericrlv .%ieru Lrrtrrs
Remaining fatigue life of riveted railway bridges.
Rating of structural and fatigue safety of old steel bridges by measurement. [Messungen an alteren Stahlbrucken zur Zustandsanalyse und Ermudungsbeurteilung.]. Brmdes, K.. Km~pp. J. mrd Hertrr, Stnhlbnu ( 1996) 6% I I ), 42 I428
J.
When evaluating old steel bridges, very often considerable reserves of the load bearing capacity are discovered. Referring to three examples, a beam grillage of a truss girder bridge. a beam girder bridge and an arch-bridge, it is pre\ented how to solve problems occurring on old steel bridges by measurement. Also, special attention is given to structural effects which can only be discovered by measurement. Graphs, I3 ref.
assessments for the ultimate limit state and fatigue and their relations to the choice of material to avoid brittle fracture. [Die Tragsicherheit, die Ermudeungssicherheit und das Sprodbruchproblem.].
The safety
Sedlucek, G.. Stmn~honrr. N.. Stmrl. Liessrm, A. Stnhlbau ( 1996) 6% I I). 407414
G.. Dnhl.
W., Lnn~enher~,
P
Fatigue properties of electroless deposited steel.
( 1996)
15. I.%& I366
The fatigue properties of 30CrMo steel electroless deposited with Ni-9.5 wt% P were studied by three-point bending fatigue tests. The microstructures before and after fracture were Characterized using SEM and eletron diffraction. The specimens were annealed before fatigue testing. Annealing at 200°C did not change the amorphous structure, but Ni-rich Ni3P crystals were found in specimens annealed at 4OO’C. Annealing at 600°C caused the coarsening of the Ni particle% in Ni3P grains or grain boundaries. The faugue strength decreased from 750 MPa and 460, 360, and 340 MPa upon annealing at 200°C for I h, 400°C for I h, and 600°C for 3 h. respectively. Shot peening before plating increased the fatigue strength of annealed samples. Fatigue striations were found m the fracture face of the coating. This indicated that fatigue crack iniuated at the outer surface of the coatings. Short and Ruvial patterns were also found, indicating a quasi-cleavage fracture. The results indicated that the fatigue properties of this steel coating primarily depend on the fatigue resistance. Photomicrographs, deffraction patterns, I2 ref.
curd
This paper presents the basic philosophy of a new method for the choice of material to avoid brittle fracture laid down in Annex C (1996) to Eurocode 3. This method allows determintion of requirements for the material toughness in the transition temperature range both from ultimate limit state and fatigue requirements and it relates these toughness-requirements to the T27J-values for the Charpy-energy specified in EN 10025, EN 101 I3 and EN 10137. The reliabilty of the method has been proved by calibration to large scale fracture mechanics test results. Comparisons of the requirements of Annex C with upper shelf requirement\ (Aufschweissbiegeversuch) and with a national guideline for the choice of material (DAST-RI 009) have been performed. Also the relationship between the Annex C-requirements and the safety assessment for old
Effect of hard anodize thickness on the fatigue of AA6061 and C355 aluminium. Rnteick. R.G. Jr., BinkoMski. T.C. md Borq B.C.. Journal of Matem& Sciencr Lrttm ( 1996) lS(lS), 1321-1323 The effect of hard anodized coatings of varying thicknesses on the fatigue strength of wrought AA6061 (T6 and T65l) and AA C355.T6 aluminium alloys was studied by producing stress-life (S-IV) curves. Hour-glass shaped specimens were subjected to rotary bend fatigue testing. The hard anodized coating thicknesses were 31-61 Nm. Both HC3 and HC5 coatings reduced the fatigue strength of the AA6061 alloy samples at all lifetimes. The maximum fatigue debit for the axial teats was -I .5 x Ioh - 2.5 x IO’ cycles. On the other hand, the HCS coating did not show significant effect on the fatigue of AA C3SS-T6 in rotary bending tests. Graphs, photomicrographs. 7 ref.