Materiais e Métodos

Sumrio3. Materiais e Mtodos23.1. Estratgia do projeto23.2. Rotas33.3. Nmero de corpos de prova43.4. Materiais53.5. Equipamentos63.6. Tratamentos trmicos73.6.4. Tratamento subzero113.6.5. Tratamento criognico123.6.6. Revenimento (Temper)134. Ensaios Previstos144.1. DIN 50100 Ensaios de fadiga, conceitos, sinais, execuo, avaliao.144.2. Determinao do tamanho de gro ASTM154.3. Ensaio de Dureza164.4. Ensaio de Impacto Charpy174.5. Sharp Notch Tensile Testing - ASTM E 338184.6. ENSAIO DE TRAO194.7. Ensaio de Compresso204.8. Ensaio de KIc214.9. Ensaio de Resistncia a Fratura224.10. Ensaio de CTOD234.11. Ensaio para Determinao de Curva R254.12. Ensaio Axial de Fadiga de Alto Ciclo em Amplitude Constante264.13. Ensaio de Fadiga de Baixo Ciclo por deformao controlada 274.14. ASTM F1160 Shear and Bending Fatigue Testing of Calcium Phosphate and Metallic Medical Coatings284.15. ASTM F1800 Standard Test Method for Cyclic Fatigue Testing of Metal Tibial Tray Components of Total Knee Joint Replacements294.16. ASTM F1440 Fatigue Testing of Metallic Stemmed Hip Arthroplasty304.17. Anlise deformao vs. nmero de ciclos31Anlise da/dN33ISO 3800 Threaded fasteners Axial load fatigue testing Test methods and evaluation of results34Ensaio de Fadiga por Flexo em quatro pontos35Ensaio de Fadiga por trao Axial36Surface-Crack Tension Test (SCT) ASTM E74037Metalografia38Plano de trabalho e cronograma39REFERNCIAS BIBLIOGRFICAS44Anexo I - Converses em Medidas de Dureza45

3. Materiais e Mtodos

3.1. Estratgia do projeto

O objetivo melhorar o desempenho fadiga de baixo ciclo e alto ciclo dos aos AISI 4140 e 4340, temperados, revenidos e tratados criogenicamente.Para tanto foram criadas rotas com os tratamentos planejados visando a obteno dos aos tratados.As propriedades mecnicas necessria a anlise da melhoria em desempenho foram colhidas na literatura e sero obtidas atravs de ensaios tencolgicos.O revenimento ser realizado em duas temperaturas distintas visando encontrar estruturas ideais para a fadigas de baixo ciclo e alto ciclo. Espera-se obter rendimento ideal para cada um.Os resultados sero comparados com as rotas iniciais de cada ao (sem tratamento) e com a rota revenida e temperada, que mais usual na indstria.Sero realizados os ensaios, nesta ordem:- Resistncia a quebra (Charpy);- Dureza (Rockwell C);- Trao (Monotnico e Cclico);- Compresso (Monotnico e Cclico);- Flexo 4 pontos (Monotnico e Cclico);- CTOD;Sero avaliadas a vida em fadiga por tenses (Wohler), por deformaes (Paris), por crescimento de trincas usando a tcnica de da/dN da mecnica da fratura.Em trabalhos futuros podero ser avaliados tambm:o impacto de sobrecargas;abertura e fechamento de trincas;

3.2. Rotas

R414140 usinadoR41-R2004140 usinado temp+revenido 200CR41-R6004140 usinado temp+revenido 600CR41-Z-R2004140 usinado temp+subzero+revenido 200CR41-Z-R6004140 usinado temp+subzero+revenido 600CR41-ZC-R2004140 usinado temp+subzero+criognico+revenido 200CR41-ZC-6R004140 usinado temp+subzero+criognico+revenido 600C

R434340 usinadoR43-R2004340 usinado+temp+revenido 200R43-R6004340 usinado+temp+revenido 600R43-Z-R2004340 usinado+temp+subzero+revenido 200CR43-Z-R6004340 usinado+temp+subzero+revenido 600CR43-ZC-R2004340 usinado+temp+subzero+criognico+revenido 200CR43-ZC-R6004340 usinado+temp+subzero+criognico+revenido 600C

Planejamento de Atividades:Ensaios:

DurezaCorpos de prova do ensaio de trao cclicaPara cada rota em triplicatasRealizar 4 medidas (pseudo-rplicas) em cada corpo em sua rea til.Medir antes e depois do ensaio de trao cclica.

Resistncia a quebra (Charpy)Corpo de prova especficos (14 * 3 = 42)Para cada rota em triplicatas

Trao monotnicaCorpos de prova especficosPara cada rota em triplicatasConsumo: 10 x 3 = 30 cps

Trao monotnica e cclica (no fazer)Em cada rota 5 cp tero interrompido o ensaio nos ciclos (102, 103, 104, 105, 106)procer o ensaio de trao monotnica com o cp em fadigaConsumo: 5 x 10 = 50 cps

Trao cclicaCorpos de prova especficos em triplicatasPara R = 0, Sa e Sm constantesPara cada rota em triplicatasConsumo: 10 x 3 = 30 cps

Corpos de prova especficos em triplicatasPara R = -0,3, Sa e Sm constantePara cada rota em triplicatasConsumo: 10 x 3 = 30 cps

3.3. Nmero de corpos de prova

ASTM E739 - informa nmeros mnimos para ensaios de fadiga

Tipo de EnsaioMnimo de CPsRplica mnima

Preliminar6 a 1217 a 33

Pesquisa e Desenvolvimento de Componentes e CPs6 a 1233 a 50

Dados Utilizveis em Projeto12 a 2450 a 75

Dados com Confiabilidade Estatstica12 a 2475 a 88

7 x 3 para identificao de tenso x deformao de cada rota10 rotas

3.4. Materiais

ao AISI 4340ao AISI 4140

Comprados na empresa

Os materiais tero sua composio qumica medida em laboratrio por anlise espectral e os resultados sero comparados com a norma ASTM SA-29, visando identificar a adequao dos mesmos.

Element43404140

Carbon0.380.43 0.380.43

Manganese 0.600.800.751.00

Phosphorus max0.0350.035

Sulfur max0.0400.040

Sillicon0.15 to 0.350.15 to 0.35

Nickel1.652.00. . .

Chromium0.700.900.801.10

Molybdenum0.200.300.150.25

Os resultados devero estar dentro das faixas apresentadas na Tabela X.

3.5. Equipamentos

Sero utilizados basicamente equipamentos disponveis na UENF e no IFF em funo da logistica de agendamento, acesso e custo do experimento.Para os ensaios de trao e flexo monotnicos ser utilizada a mquinas

e equiMTS, modelo 810, com capacidade de 100 kNcontroladores digitais servo-hidrulicos MultiPurpose TestWare da MTS.

Instronquantidade medida para corpos de prova

Dureza

3.6. Tratamentos trmicos

tmpera x graus ; y tempoarrefecimento por leo at x graus

Andrews (1965):As temperaturas Ms e Mf dos aos foram calculadas utilizando-se a equao experimental de Andrews (1965):

Ms(C) = 539 - 423*(%C)-30,4(%Mn)-17,7(%Ni)-12,1(%Cr)-7,5(%Mo)-7,5(%Si)(+/-13C) (1)Mf(C) = MS - 215 (+/- 15C) (2)

costa e mei 2010pg 283

revenido 600 durante 1 hora

Esquema de tratamento trmico para avaliao do fenmeno da FMR.Tr: 250oC, 350oC, 400oC e 450oC.

jose b marcomini

4. Tratamentos Trmicospara cada lote de rota:preparar austenitizaopreparar martmperapreparar subzeropreparar criognicopreparar revenimento (240 ou 600C)Executar austenitizao

3.6.1. pr-austenitizaoagendar tcnicos para austenitizaoprepara corpos de provaAquecer forno para austenitizar at atingir temperatura 820preparar martmpera

4.6.2. Austenitizao

Medir temperatura do fornoAnotar hora e temperatura de entrada no fornoColocar corpos de prova no fornoMonitorar temperatura do forno e tempo (1 hora)Anotar temperatura e hora de sada do fornoexecutar martmpera

4.6.3. Martmpera

Pr-martmperaAgendar tcnicos para martmperaPreparar leo na temperatura Ms + 50 (martmpera)Monitorar a temperatura do leo com termopar Ms + 50

Medir temperatura do leo (Ms + 50C)Anotar temperatura e hora do incio do procedimentoLevar corpos do forno para banho em leoMonitorar tempo e temperatura do corpo (1 hora)Ao chegar na temperatura Mf retirar do banhoArrefecer em gua corrente o mais rpido possvel para < 100CAguardar temperatura ambienteexecutar subzero

3.6.4. Tratamento subzero

resfriamento intermedirio para 90 graus y temponitrognio lquido em x graus y tempoarrefecimento em temperatura ambiente

Pr-subzeroAgendar tcnicos para subzeroAgendar freezer (confirmar -80C)Verificar se tem espao e deixar isopor no lugarLocalizar armao arame

4c. SubzeroColocar corpos de prova na armao de arameMedir temperatura do freezer (min -80C)anotar hora e temperaturaDepositar corpos no freezerAguardar um (1) diaMedir temperaturaanotar data e horaRetirar do freezerexecutar criognico

3.6.5. Tratamento criognico

Pr-criognicoAgendar tcnicos para tratamento criognicoContactar Fernando para agendar a obteno do NitrognioColher o Nitrognio Lquido para cmera

4d. CriognicoMedir temperatura na cmaraColocar corpos de prova na cmara com Nitrognio LquidoManter no tratamento por um (1) diaMedir temperatura do corpoAguardar ao ar arrefecimento lento para temperatura ambiente (1 dia)executar revenimento

3.6.6. Revenimento (Temper)

Pr-revenimento (240C)Agendar tcnicos para revenimentoMonitorar a temperatura do forno (240C)Preparar banho em gua corrente


4e. Tratamento Trmico: Revenido (a 240C)medir temperatura do forno (exatos 600C)anotar hora e temperaturaDepositar corpos de prova no fornoMonitorar tempo e temperatura de revenimento (1 hora)Arrefecer em gua corrente o mais rpido possvel para < 100C

4f. Tratamento Trmico: Revenido (a 600C)medir temperatura do forno (exatos 600C)anotar hora e temperaturaDepositar corpos de prova no fornoMonitorar tempo e temperatura de revenimento (1 hora)Arrefecer em gua corrente o mais rpido possvel para < 100C

3.7. Ensaios Previstos

3.7.1. DIN 50100 Ensaios de fadiga, conceitos, sinais, execuo, avaliao.

3.7.2. Determinao do tamanho de gro ASTM

E 11-96 Test methods for determining the average grain sise, 03.01.

ASTM E112 ?

3.7.3. Ensaio de Dureza

O ensaio de dureza deve ser realizado de acordo com a norma ASTM A-370 [25].A escala utilizada foi a Rockwell C.A carga aplicada foi de 150 kg.

As medidas sero realizadas em quatro pontos distintos, na rea til do corpo de prova.Sero analisados trs corpos de prova de cada rota (trplicas).As anlises sero realizadas aps a usinagem nas rotas R1 e R3 (conforme fornecido), e aps os tratamentos trmicos em todas as outras.Sero medidos adicionalmente, nas rotas R1 e R3, em triplicata, aps a tmpera.Ser medido um corpo de prova na condio conforme recebido e um corpo de prova tratado por tmpera, um corpo de prova revenido medido em cinco pontos distintos, no podendo apresentar nenhum resultado acima de 225 HB. Ser utilizada a escala de dureza BrinEnsaios de dureza conforme ASTM A 370, rev. A, 2007

O durmetro a ser utilizado com escala em HRC com incerteza de medio de +/- 0,6HRC.

A dureza HB segundo a ABNT para os aos esto apresentadas na Tabela X:

Aodim. 13 mmdim. 25 mmdim. 50 mmdim. 100 mm

4140302302285241

4340388363341321

25. ASTM A370, Standart Test Methods and Definitions for Mechanical Testinhg of Steel Products, ASTM International, 2007.

3.7.4. Ensaio de Impacto Charpy

Norma ASTM E-23

O ensaio segue os princpios da norma ASTM A370. Sero realizados trs testes para os aos conforme recebidos, alm de trs testes para cada rota deste trabalho, visando obteno da mdia destes ensaios. Espera-se obter como resultado uma energia absorvida maior ou igual a 54 J. Nenhum dos trs resultados podero apresentar valor inferior a 47 J e a fratura deve ter aparncia dctil superior a metade (Eckstein, 2006).

Corpo-de-prova Charpy com entalhe em U conforme norma da ASM (ASM, 2000)

3.7.5. Sharp Notch Tensile Testing - ASTM E 338

"Standard Test Method for Sharp-Notch Tension Testing of High-Strength Sheet Materials"ASTM E338 covers the determination of a comparative measure of the resistance of sheet materials to unstable fracture originating from a very sharp stress-concentrator or crack. It relates specifically to fracture under continuously increasing load and excludes conditions of loading that produce creep or fatigue. The quantity determined is the sharp-notch strength of a specimen of particular dimensions, and this value depends upon these dimensions as well as the characteristics of the material. In addition to the sharp-notch strength, the yield strength ratio is also determined.

This method is not intended to provide an absolute measure of resistance to crack propagation which might be used in calculations of the strength of structures. However, it can serve a number of purposes.

In the research and development of materials it can be used to understand how fracture characteristics are affected by such variables as chemical composition, processing, heat-treatment, etc.

In design applications, it is often used to compare the relative crack-propagation resistance of a number of materials which are otherwise equally suitable for an application, or to eliminate materials when an arbitrary minimum acceptable sharp-notch strength can be established.

ASTM E338 can be used for specifications of acceptance and quality control when there is a sound basis for establishing a minimum acceptable sharp-notch strength

The sharp-notch strength may decrease rapidly through a narrow range of decreasing temperature. This temperature range and the rate of decrease depend on the material and its thickness. The temperature of the specimen during each test are therefore controlled and recorded. Tests are conducted throughout the range of expected service temperatures to ascertain the relation between notch strength and temperature. For design applications, care should be taken that the lowest and highest anticipated service temperatures, they are included in the testing program.

In addition to performing Sharp-Notch Tensile Testing for you, Touchstone can assist you in the development of your complete test program.

3.7.6. ENSAIO DE TRAO

ensaios de trao conforme ASTM A 370, rev. A, 2007

A mquina de ensaios ser Usando a Instron

de acordo com ASTM A-370 [25]

25. ASTM A370, Standart Test Methods and Definitions for Mechanical Testing of Steel Products, ASTM International, 2007.

Tensile Testing of Metals - ASTM E 8

"Standard Test Method for Tension Testing of Metallic Materials"The ASTM E8 method covers the tension testing of metallic materials in any form at room temperature, specifically, the methods of determination of yield strength, yield point, tensile strength, elongation, and reduction of area.

Tension tests determine the strength and ductility of materials under uniaxial tensile stresses. This information may be helpful in comparisons of materials, in the development of new alloys, for quality control, to support structural design, and acceptance testing for commercial shipments.

Grip and face selection are very important to obtain accurate results. Specimen alignment is key to avoid side loading or bending moments. Touchstones extensive experience in composites testing, which are more sensitive to alignment, ensures control of this critical parameter in testing metallic materials. This is particularly important for R&D projects, where a reference standard or specification may not be available, and improper alignment could yield results that are incorrect but unknown.

In addition to mechanical testing capability, for tests such as ASTM E8 and many other ASTM methods, Touchstone can conduct complete metallurgical and/or failure analysis using its laboratories for light microscopy, scanning electron microscopy (SEM), and metallography.

Reference: ASTM E8 Standard Test Method for Tension Testing of Metallic Materials

3.7.7. Ensaio de Compresso

Compression Testing of Metals - ASTM E 9"Standard Test Method for the Compression Testing of Metallic Materials at Room Temperature"

ASTM E9 covers the apparatus, specimens, and procedure for axial-load compression testing of metallic materials at room temperature. Touchstone has at times performed a modification of this test at elevated and cryogenic temperatures.

Normally, the specimen is subjected to an increasing axial compressive load. Both load and strain are monitored either continuously or in finite increments, and the compressive properties are determined.

The data obtained from a compression test may include the yield strength, the yield point, Young's modulus, the stress-strain curve, and the compressive strength. In the case of a material that does not fail in compression by a shattering fracture, compressive strength is a value that is dependent on total strain and specimen geometry.

Compressive properties are of interest in the analyses of structures subject to compressive or bending loads or both and in the analyses of metal working and fabrication processes that involve large compressive deformation such as forging and rolling.

For brittle or nonductile metals that fracture in tension at stresses below the yield strength, compression tests offer the possibility of extending the strain range of the stress-strain data. While the compression test is not complicated by necking as is the tension test for certain metallic materials, buckling and barreling can complicate results and should be minimized.

3.7.8. Ensaio de KIc

Fracture Toughness of Metals (K-value) - ASTM E 399ASTM E 399 - Standard Test Method for Plane-Strain Fracture Toughness of Metallic Materials

ASTM E399 covers the determination of the plane-strain fracture toughness (KIc) of metallic materials by tests using a variety of fatigue-cracked specimens having a thickness of 0.063 in. (1.6 mm) or greater.

E399 also covers the determination of the specimen strength ratio Rxx where x refers to the specific specimen configuration being tested. This strength ratio is a function of the maximum load the specimen can sustain, its initial dimensions and the yield strength of the material.

ASTM E399 involves the testing of notched specimens that have been precracked in fatigue by loading either in tension or three-point bending.

Load versus displacement across the notch at the specimen edge is recorded autographically.

The load corresponding to a 2% apparent increment of crack extension is established by a specified deviation from the linear portion of the record.

The KIc value is calculated from this load by equations that have been established on the basis of elastic stress analysis of specimens of the types described in this method.

The validity of the determination of the KIc value by this test method depends upon the establishment of a sharp-crack condition at the tip of the fatigue crack, in a specimen of adequate size.

To establish a suitable crack-tip condition, the stress intensity level at which the fatigue precracking of the specimen is conducted is limited to a relatively low value.

The property KIc determined by this test method characterizes the resistance of a material to fracture in a neutral environment in the presence of a sharp crack under severe tensile constraint, such that the state of stress near the crack front approaches tritensile plane strain, and the crack-tip plastic region is small compared with the crack size and specimen dimensions in the constraint direction.

A KIc value is believed to represent a lower limiting value of fracture toughness. This value may be used to estimate the relation between failure stress and defect size for a material in service wherein the conditions of high constraint described above would be expected.

3.7.9. Ensaio de Resistncia a Fratura

Fracture Toughness of Metals ASTM E1820 (elastic/plastic)

The ASTM E1820 test determines the fracture toughness of metals using the parameters of K, J, and Crack-Tip Opening Displacement (CTOD). The fracture toughness is calculated by taking a fatigue, pre-cracked specimen with a notch and using a double cantilever to push the two sides of the notch away from each other. This allows our technicians to observe how the sample splits. There are three possibilities of how the specimen could split: fracture instability which results in a single point-value of fracture toughness, stable tearing which results in an R-curve, and stable tearing interrupted by fracture instability which results in an R-curve that ends at the point of instability. These values could be used for material comparison by yield strength, selection, and quality assurance. They could also help set a standard for structural flaw assessment.

Reference: Standard Test Method for Measurement of Fracture Toughness ASTM E1820

3.7.10. Ensaio de CTOD

ASTM E1290 Standard Test Method for Crack-Tip Opening Displacement (CTOD) Fracture Toughness Measurement

CTOD (Crack Tip Opening Displacement) uma das formas de medir a tenacidadea fratura do material,

22. Eckstein, C. B., Additional Requirements for Cr-Mo Low Alloy Steel, Cenpes, Petrobras, 2006.

25. ASTM A370, Standart Test Methods and Definitions for Mechanical Testinhg of Steel Products, ASTM International, 2007.

Determinao de KIcJIcCTODc eFCGR

Para dureza (toughness):

ASTM E 399: Standard Test Method for Plane-Strain Fracture Toughness of Metallic Materials. This is the oldest standard, and contains a number of specimen configurations for toughness testing.

ASTM E 1820: Standard Test Method for Measurement of Fracture Toughness.This new, comprehensive standard covers critical K, J and CTOD testing for bothpoint values (like KIc) or R-curves.

ASTM E 1304, Standard Test Method for Plane-Strain (Chevron-Notch) Fracture Toughness of Metallic Materials. Two chevron-notch configurations. See Note 1, Scope, to relate results from E 1304 to those from E 399.

capacidade do material se deformar plasticamente atravs da medio das faces da fissura preexistente no corpo de prova, de acordo com a norma BS 7448

altura do cp: W = alturaespessura do cp: B = 0,5Wdistncia entre suportes: S = 4 Wentalhe mecnico mais a fissura: a = entre 0,45W at 0,55W

pr-compresso

ensaio de fadiga para abrir a pr-trinca segundo especificao, equao para clculo da carga a ser aplicada e sua dimenso limite [53]

3.7.11. Ensaio para Determinao de Curva R

R-Curve Determination - ASTM E 561

ASTM E 561 covers the determination of resistance to fracturing of metallic materials by R-curves using either the center-cracked tension panel M(T), the compact specimen C(T), or the crack-line wedge-loaded specimen C(W), to deliver applied stress intensity factor, K, to the material. An R-curve is a continuous record of toughness development in terms of KR plotted against crack extension in the material as a crack is driven with a continuously increased stress intensity factor, K.

R-curves characterize the resistance to fracture of materials during incremental slow-stable crack extension and result from growth of the plastic zone as the crack extends from a sharp notch. They provide a record of the toughness development as a crack is driven stably under increasing applied K. They are dependent upon specimen thickness, temperature, and strain rate.

3.7.12. Ensaio Axial de Fadiga de Alto Ciclo em Amplitude Constante

STP 566 [12], publicada pela ASTM, os corpos-de-prova paraensaios de flexo rotativa devem possuir a geometria apresentada na figura II.5 e seuacabamento superficial deve ser obtido com o polimento at a obteno de uma superfcieespelhada de forma a diminuir-se a variabilidade e a influencia do acabamento superficial naresistncia fadiga do material.

STP 566 ASTM Handbook of Fatigue Testing ,1974

High Cycle Fatigue - ASTM E 466ASTM E466 - Standard Test Method for Conducting Constant Amplitude Axial Fatigue Tests of Metallic Materials

Touchstone is experienced in the performance of fatigue testing in almost every material system and at a wide variety of temperatures from cryogenic to over 2200 degrees Fahrenheit.

Machining methods and techniques can strongly influence the fatigue life of a material. Proper machining techniques prevent the introduction of stress risers or crack initiation sites. Touchstone is experienced in fatigue specimen preparation to comply with strict sample preparation requirements, including surface finish of the machined sample. This knowledge and care provides the most meaningful and best possible high cycle fatigue life results.

ASTM E466 conducts axial fatigue tests to obtain the fatigue strength of metallic materials in the fatigue regime where the strains are predominately elastic both upon initial loading and throughout the test.

The method is limited to the fatigue testing of axial unnotched and notched specimens subjected to constant amplitude, periodic forcing function in air at room temperature. This practice is not intended for application in axial fatigue tests of components or parts.

The ASTM E466 axial load fatigue test is used to determine the effect of variations in material, geometry, surface condition, stress, etc., on the fatigue resistance of metallic materials subjected to direct stress for relatively large number of cycles. The test may also be used as a guide to the selection of metallic materials for service under conditions of repeated direct stress.

Reference: ASTM E466 - Standard Test Method for Conducting Constant Amplitude Axial Fatigue Tests of Metallic Materials

3.7.13. Ensaio de Fadiga de Baixo Ciclo por deformao controlada

Low Cycle Fatigue - ASTM E 606

"ASTM E606 - Standard Test Method for " Strain-Controlled Fatigue Testing"This Low Cycle Fatigue testing method covers the determination of low-cycle fatigue properties of nominally homogeneous metallic materials by the use of uniaxially loaded test specimens. It is intended as a guide for low-cycle fatigue testing performed in support of such activities as materials research and development, mechanical design, process and quality control, product performance, and failure analysis.

Although low-cycle fatigue is a phenomenon that is influenced by many of the same variables that influence high-cycle fatigue, the nature of low-cycle fatigue imposes distinctive requirements on fatigue testing methods.

In particular, the cyclic total strain should be measured and cyclic plastic strain should be determined. Furthermore, either of these strains typically are used to establish cyclic limits; total strain usually is controlled throughout the cycle. The uniqueness of this recommended practice and the results it yields is the determination of cyclic stresses and strains throughout the tests.

Low-cycle fatigue can be an important consideration in the design of industrial products. It is important for situations in which components or portions of components undergo either mechanically or thermally induced cyclic plastic strains that cause failure within relatively few cycles. Information obtained from low-cycle fatigue testing may be an important element in the establishment of design criteria to protect against component failure by fatigue.

Low-cycle fatigue test results are useful in the areas of mechanical design as well as materials research and development, process and quality control, product performance, and failure analysis. Results of a low-cycle fatigue test program may be used in the formulation of empirical relationships between the cyclic variables of stress, total strain, plastic strain, and fatigue life. They are commonly used in data correlations such as curves of cyclic stress or strain versus life and cyclic stress versus cyclic plastic strain. Examination of the cyclic stress-strain curve and its comparison with monotonic stress strain curves gives useful information regarding the cyclic stability of a material, for example, whether the values of hardness, yield point, yield strength, and strain hardening exponent will increase or decrease (that is, whether a material will harden or soften) due to cyclic plastic straining. Results of the uniaxial tests on specimens of simple geometry can be applied to the design of components with notches or other complex shapes provided that the strains can be determined and multiaxial states of stress or strain and their gradients are correctly correlated with the uniaxial strain data.

Reference: ASTM E606 - Standard Practice for Strain-Controlled Fatigue Testing

3.7.14. ASTM F1160Shear and Bending Fatigue Testing of Calcium Phosphate and Metallic Medical Coatings

3.7.15. ASTM F1800Standard Test Method for Cyclic Fatigue Testing of Metal Tibial Tray Components of Total Knee Joint Replacements

3.7.16. ASTM F1440Fatigue Testing of Metallic Stemmed Hip Arthroplasty

3.7.17. Anlise deformao vs. nmero de ciclos

3.7.18. Tratamentos estatsticos

Os dados obtidos atravs de ensaio normatizados devero atender s condies:

a) A vida em fadiga seja um dado aleatrio;b) Inexistncia de testes suspensos;(Nenhum corpo-de-prova com ensaio suspenso por vida infinita pode ser includo)c) Possibilidade de a curva ser descrita na forma: Y = A + BX(X corresponde amplitude de tenso e Y nmero de ciclos medido at a falha)d) A vida em fadiga varivel aleatria descrita por uma distribuio log-Normal;e) A varincia da distribuio constante.

As estimativas dos coeficientes A e B podem ser determinadas por:

(equao X)

Onde:

Xi = log Si: i variando at k corpos de prova ensaiados ;Yi = log Ni: i variando at l nveis de tenso ;

k Nmero total de corpos-de-prova ensaiados em 50%, 60% e 70% do Limite de Resistncia

Intervalo de confiana

Onde o parmetro tp vem da Tabela de distribuio de Student, a partir dos graus de liberdade e com o nvel de confiana de 95%, (ASTM E739, 2004).

Desta forma os coeficientes sero estimados para cada rota de tratamento ensaiada por fadiga.

3.7.19. Anlise da/dN

Fatigue Crack Growth (da/dN) - ASTM E 647"Standard Test Method for Measurement of Fatigue Crack Growth Rates"

ASTM E647 covers the determination of steady-state fatigue crack growth rates from near-threshold to Kmax controlled instability using either compact type, C (T), or center-cracked-tension, M (T), specimens. Results are expressed in terms of the crack-tip stress-intensity factor range (DK), defined by the theory of linear elasticity.

This test method involves cyclic loading of notched specimens which have been acceptably pre-cracked in fatigue. Crack length is measured, either visually or by an equivalent method, as a function of elapsed fatigue cycles and these data are subjected to numerical analysis to establish the rate of crack growth. Crack growth rates are expressed as a function of the stress-intensity factor range, DK, which is calculated from expressions based on linear elastic stress analysis.

Fatigue crack growth rate expressed as a function of crack-tip distress-intensity factor range, da/dN versus DK, characterizes a material's resistance to stable crack extension under cyclic loading.

3.7.20. ISO 3800 Threaded fasteners Axial load fatigue testing Test methods and evaluation of results

3.7.21. Ensaio de Fadiga por Flexo em quatro pontos

MTS 810 com capacidade de 100 kN (em trao ou compresso),

Parmetros do ensaio

deformao plstica acumuladafadiga de baixo cicloFrequncia 0,5 HzNmero de ciclos 6000Controle de deslocamento 5,5 - 0m

Amplitude constante:tenso mxima e razo de fadiga (R = mnima/mxima)amplitude de tenso e tenso mdia

3.7.22. Ensaio de Fadiga por trao Axial

3.7.23. Surface-Crack Tension Test (SCT) ASTM E740

This practice is the design, preparation, and testing of a metal sample containing a surface-crack. The ASTM E740 procedure is used to calculate the load-carrying capacity of structural components that have a possible type of flaw. It can also be used for research and development purposes to investigate the failure tendencies of a cracked metal.

This particular standard relates solely to testing under a continuously increasing load however, Touchstone is able to test it under cyclic and sustained loading conditions also.

The test is performed by creating a small semi-elliptical crack in a sample, applying tremendous amounts of increasing pressure to the top of that sample until fracture, and recording the maximum pressure it could withstand before cracking. There is no limit to the strength, toughness, or thickness of the sample. The final calculations include the maximum load withstood and the residual strength.

Reference: ASTM E740 Standard Practice for Fracture Testing with Surface-Crack Tension Specimens

3.7.25. Metalografia

Avaliao em raio x

avaliao em microscopia tica

avaliao em microscopia eletrnica

Anlise de microscopia eletrnica de varredura (MEV)

Anlise de difrao de raios-X

-----------------------------------------

4. Plano de trabalho e cronograma

Macro - Atividades2014-12014-22014-32014-42015-12015-22015-32015-4

1.Reviso Bibliogrficaxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

2.Aquisio do materialx

3.Usinagemxxxx

4.Tratamento Trmicoxx

5.Experimentosxxxxxxxxxxxxxxxxxxxxxxx

6.Anlise dos resultadosx xx x x xx x x xx x x x

7.Escrita dos resultadosx xx x x xx x x xx x x x

8.Elaborao da Tesex x x xx x x x x x x x x x x xx x x x xxxxxxxxxxxx

9.Apresentaox

10.Acerto de sugestesxxxx

11.Entrega finalx

4.2. Checklist de Atividades necessrias

1. Reviso de BibliogrficaEncontrar mais artigos cientficos e teses de doutorado sobre a criogenia e fadiga.Ler e resumir cada umAcrescentar no texto da tese o que couber.

2. Aquisio de materiaisLocalizar armao arame para tratamento criognicoComprar Cmara Nitrognio LquidoComprar Medidor de temperatura laserContabilizar quantidade de corpos de cada ensaioCalcular perdas percentuais em cada ensaioCalcular tamanho total da compraEntrar em contato com o vendedorReceber e verificar as quantidadesSolicitar anlise qumicaAceite final da compra

3. UsinagemEntrar em contato com setor da UENF e do IFFAlternativamente contratar empresa localAgendar visita para: Identificao do maquinrio e metodologia Combinar de estar presente duranteApresentao dos parmetros e requisitos da teseReceber paulatinamente pequenos lotes de entregveisConferncia dos parmetros dos corpos de provaPolir superfcies corpos de prova para fadiga

4. Tratamentos Trmicospara cada lote de rota:preparar austenitizaopreparar martmperapreparar subzeropreparar criognicopreparar revenimento (240 ou 600C)Executar austenitizao

pr-austenitizaoagendar tcnicos para austenitizaoprepara corpos de provaAquecer forno para austenitizar at atingir temperatura 820preparar martmpera

Pr-martmperaAgendar tcnicos para martmperaPreparar leo na temperatura Ms + 50 (martmpera)Monitorar a temperatura do leo com termopar Ms + 50

Pr-subzeroAgendar tcnicos para subzeroAgendar freezer (confirmar -80C)Verificar se tem espao e deixar isopor no lugarLocalizar armao arame

Pr-criognicoAgendar tcnicos para tratamento criognicoContactar Fernando para agendar a obteno do NitrognioColher o Nitrognio Lquido para cmera



4a. Tratamento Trmico: AustenitizaoMedir temperatura do fornoAnotar hora e temperatura de entrada no fornoColocar corpos de prova no fornoMonitorar temperatura do forno e tempo (1 hora)Anotar temperatura e hora de sada do fornoexecutar martmpera

4b. Tratamento Trmico: MartmperaMedir temperatura do leo (Ms + 50C)Anotar temperatura e hora do incio do procedimentoLevar corpos do forno para banho em leoMonitorar tempo e temperatura do corpo (1 hora)Ao chegar na temperatura Mf retirar do banhoArrefecer em gua corrente o mais rpido possvel para < 100CAguardar temperatura ambienteexecutar subzero

4c. SubzeroColocar corpos de prova na armao de arameMedir temperatura do freezer (min -80C)anotar hora e temperaturaDepositar corpos no freezerAguardar um (1) diaMedir temperaturaanotar data e horaRetirar do freezerexecutar criognico

4d. CriognicoMedir temperatura na cmaraColocar corpos de prova na cmara com Nitrognio LquidoManter no tratamento por um (1) diaMedir temperatura do corpoAguardar ao ar arrefecimento lento para temperatura ambiente (1 dia)executar revenimento

4e. Tratamento Trmico: Revenido (a 240C)medir temperatura do forno (exatos 600C)anotar hora e temperaturaDepositar corpos de prova no fornoMonitorar tempo e temperatura de revenimento (1 hora)Arrefecer em gua corrente o mais rpido possvel para < 100C

4f. Tratamento Trmico: Revenido (a 600C)medir temperatura do forno (exatos 600C)anotar hora e temperaturaDepositar corpos de prova no fornoMonitorar tempo e temperatura de revenimento (1 hora)Arrefecer em gua corrente o mais rpido possvel para < 100C

5. Experimentos6.Anlise dos resultados7.Escrita dos resultados8.Elaborao da Tese9.Apresentao10.Acerto de sugestes11.Entrega final

5. REFERNCIAS BIBLIOGRFICAS

ASM. ASM Handbook, Vol. 8 Mechanical Test and Evaluation, 2000

ASTM E-739-91, Practice for statistical analysis of linear or linearized stress-life (S-N) and strain-life (-N) fatigue data', Annual Book of ASTM Standards, ASTM, West Conshohocken, PA, 1998.

22. Eckstein, C. B., Additional Requirements for Cr-Mo Low Alloy Steel, Cenpes, Petrobras, 2006.

[51]http://www.moldesinjecaoplasticos.com.br/tolerancias.asp

[52] British Standard, 1991, Part 2, Method for determination of Kc, critical CTOD andcritical J values of metallic materials, BS, 7448.

[53] British Standard, 1991, Part 1, Method for determination of Kc, critical CTOD andcritical J values of metallic materials, BS, 7448.

[56] ISO TR 15608: Welding Guidelines for a metallic materials grouping system,2005.

[58] ISO 12106: 2003 Metallic materials - Fatigue testing - Axial Strain ControlledMethod.

[33] Pereira, H.F. Comportamento fadiga de componentes estruturais sob a ao desolicitaes de amplitude varivel. Departamento de Engenharia Mecnica, Universidade do Porto. Lisboa: Dissertao de Mestrado, 2006.

[44] ISO 6892: 2009 Metallic materials - Tensile testing - Method of test at roomtemperature.

[49] EN 1993-1-9:2005-07, Eurocode 3: Design of steel structures. Part 1-9: Fatigue,Eurocode 3, CEN European Committee for Standardization, Brussels, Belgium, 2005.

STP 566 ASTM Handbook of Fatigue Testing ,1974

Chaves, Antnio de Pdua. Estudo comparativo da vida em fadiga de aos fundidos e forjados de alta resistncia para utilizao em acessrios de linhas de ancoragem deplataformas offshore dissertao de mestrado. Rio de Janeiro. CEFET RJ. p. 93. 2010.

ANLISE DE FADIGA EM MATERIAIS DCTEIS ATRAVS DE UMA FORMULAO LOCALMENTE ACOPLADA DA MECNICA DO DANO CONTNUO

Anexo I - Converses em Medidas de Dureza ROCKWELL|ROCKWEEL SUPERF.|VICKERSBRIN.LR aprx.

HRCHRBHRA|15 N30 N45 N|HVHBN/MM2

60-81.290.277.566.6697654-

59-80.789.876.665.5674634-

58-80.189.375.764.3653615-

57-79.688.974.863.2633595-

56-7988.373.962613577-

5512078.587.97360.95955602075

547887.47259.85775432015

5311977.486.971.258.65605251950

5211976.886.470.257.45445121880

5176.385.969.456.15284961820

5011775.985.568.5555134011760

4911775.28567.653.84984691696

4874.784.566.752.54844551634

4711674.183.96551.44714431579

4611573.683.564.850.34584321531

4511573.18364494464211480

4411472.582.563.147.84344091434

43728262.246.74234001386

4211371.581.561.345.54123091340

4111270.980.960.444.34023811296

4011270.480.459.543.13923711250

3969.979.958.641.93823621215

3811069.479.457.740.83723531179

3711060.978.85639.63633441160

36(109)68.478.355.938.43543361115

35(108.5)67.977.75537.23453271080

34(108)67.477.254.236.13363191054

33(107.5)66.876.653.334.93273111025

32(107)66.376.152.133.73183011000

31(106)65.875.651.332.5310294979

30(105.5)65.37550.431.3302286952

29(104.5)64.774.549.530.1294279931

28(104)64.373.948.628.9286271910

27(103)63.873.347.727.8279264882

26(102.5)63.372.846.826.7272258862

25(101.5)62.872.245.925.5266253840

24(101)62.471.64524.3260247825

2310062714423.1254243805

229961.570.543.222248237785

2198.56169.942.320.7243231770

2097.860.569.441.519.6238226760

Documents

Materiais e Métodos