Study on the Uniaxial Cyclic Behaviors of Primary Auxiliary Piping Materials in

Nuclear Power Plant at room and Elevated Temperatures

Reporter: Yong WangSupervisor: Professor Xu Chen

contentscontents

• significance of choosing this topic• Literature Review• project planning

• significance of choosing this topic• Literature Review• project planning

significance of choosing this topic• Engineering components are often subjected to

cyclic load and the cyclic plastic deformation of engineering materials thus becomes inevitable.

• Engineering components are often subjected to cyclic load and the cyclic plastic deformation of engineering materials thus becomes inevitable.

Under asymmetrical cyclic stressing, cyclic accumulation of plastic deformation, denoted as ratcheting, takes place.

Under asymmetrical cyclic stressing, cyclic accumulation of plastic deformation, denoted as ratcheting, takes place.

ratcheting is very important and should be addressed in the safety assessment and fatigue life estimation of the materials and structure components. Design criteria for nuclear power plants, such as ASME Code Section III, KTA and RCC-MR, all require ratcheting analysis.

ratcheting is very important and should be addressed in the safety assessment and fatigue life estimation of the materials and structure components. Design criteria for nuclear power plants, such as ASME Code Section III, KTA and RCC-MR, all require ratcheting analysis.

References• [1] J.L. Chaboche, D. Nouailhas, Constitutive modeling of ratcheting effects.

Part I. Experimental facts and properties of classical models, ASME J. Eng. Mater. Technol. 111 (4)(1989) 384–392.

• [2] M.D. Ruggles, E. Krempl, The interaction of cyclic hardening and ratcheting for AISI type 304 stainless steel at room temperature. I. Experiments, J.Mech. Phys. Solids 38 (4) (1990) 575–585.

• [3] P. Delobelle, P. Robinet, L. Bocher, Experimental study and phenomenological modelization of ratcheting under uniaxial and biaxial loading on an austenitic stainless steel,Int. J. Plast. 11 (4) (1995) 295–330.

• [4] D.L. McDowell, Stress state dependence of cyclic ratcheting behavior of two rail steels, Int. J. Plast. 11 (4) (1995)397–421.

• [5] M. Kobayashi, N. Ohno, T. Igari, Ratcheting characteristics of 316FR steel at high temperature, Int. J. Plast. 14(4–5) (1998) 355–390.

• [6] M. Mizuno, Y. Mima, M. Abdel-Karim, N. Ohno,Uniaxial ratcheting of 316FR steel at room temperature.I. Experiments, ASME J. Eng. Mater. Technol. 122 (1)(2000) 29–34.

References• [7] G.Z. Kang, Q. Gao, X.J. Yang, Y.F. Sun, An experimental study on uniaxial

and multiaxial strain cyclic characteristics and ratcheting of 316L stainless steel, J. Mater. Sci.Technol. 17 (2) (2001) 219–223.

• [8] G.Z. Kang, Q. Gao, L.X. Cai, X.J. Yang, Y.F. Sun,Experimental study on the non-proportional cyclic plasticity of U71Mn rail steel at room temperature, J. Mater.Sci. Technol. 18 (1) (2002) 13–16.

• [9] G.Z. Kang, Q. Gao, L.X. Cai, Y.F. Sun, Experimental study on uniaxial and nonproportionally multiaxial ratcheting of SS304 stainless at room and high temperatures,Nucl. Eng. Des. 216 (2002) 13–26.

• [10] G.Z. Kang, Q. Gao, X.J. Yang, Experimental study on the cyclic deformation and plastic flow of U71Mn rail steel,Int. J. Mech. Sci. 44 (8) (2002) 1645–1661.

• [11] Yu, D., et al. Visco-plastic constitutive modeling on Ohno–Wang kinematic hardening rule for uniaxial ratcheting behavior of Z2CND18.12N steel. Int. J. Plasticity (2011), doi:10.1016/j.ijplas.2011.06.001.

• [12] Zhu J et al. Bending ratcheting tests of Z2CND18.12 stainless steel. Int J Fatigue (2011), doi:10.1016/j.ijfatigue.2011.04.008.

Material categoriesMaterial categories

• cyclic hardening materials:SS304,316FR,316L, Z2CND18.12 et al.• cyclically stable materials(within a limited cyclic

number):U71Mn rail steel ,ordinary carbon steel et al.

• cyclic softening materials: 25CDV4.11 steel et al.

summary

• Cyclic hardening/softening behavior, stress magnitude ,mean stress, loading rate, loading history , loading pattern (proportional or non-proportional) ,temperature are some of the variables that would influence the material ratcheting phenomena.

• Cyclic hardening/softening behavior, stress magnitude ,mean stress, loading rate, loading history , loading pattern (proportional or non-proportional) ,temperature are some of the variables that would influence the material ratcheting phenomena.

Existing problemsPrimary auxiliary pipeline in nuclear power Plant endures thermal

cyclic loading induced by power on and off of reactors. It is necessary to study cyclic behaviors influenced by thermal cyclic aging.

Primary auxiliary pipeline in nuclear power Plant endures thermal cyclic loading induced by power on and off of reactors. It is necessary to study cyclic behaviors influenced by thermal cyclic aging.

It has been found that variation of ambient temperature is common to structure components of nuclear system, and the effect of ambient temperature on the ratcheting is remarkable. Therefore, Cyclic tests should be done to investigate the strain stress response of Z2CND18.12 at high temperature(350 )℃ .

It has been found that variation of ambient temperature is common to structure components of nuclear system, and the effect of ambient temperature on the ratcheting is remarkable. Therefore, Cyclic tests should be done to investigate the strain stress response of Z2CND18.12 at high temperature(350 )℃ .

thermal shock may occur due to temperature control failure. So, in this case, cyclic tests should be included for thermal shock specimens.thermal shock may occur due to temperature control failure. So, in this case, cyclic tests should be included for thermal shock specimens.

Pre-stress/pre-strain cyclic tests are needed for pipeline may endure high loading shock induced by seismic loading.Pre-stress/pre-strain cyclic tests are needed for pipeline may endure high loading shock induced by seismic loading.

experiment apparatusexperiment apparatus

• high temperature fatigue testing machine

Geometry of the specimenGeometry of the specimen

Thickness:4.5mm

Specimens were fabricated from primary auxiliary heattransport pipes in nuclear power Plant with 76 mm outer diameter and 4.5 mm wall thickness

Specimens were fabricated from primary auxiliary heattransport pipes in nuclear power Plant with 76 mm outer diameter and 4.5 mm wall thickness

Monotonic tensionMonotonic tension

Specimens MT-1 MT-2 MT3

Strain rate 1×10-3/s 1×10-4/s 1×10-5/s

It has been found that Z2CND18.12 austenitic stainless steel is rate-dependent material(Yu, D., et al.,2011) . So monotonic tensile were performed at various strain rate to understand this feature.

Thermal cyclic aging tests

Firstly, Specimens were preheated for 30 and 60 cycles, respectively

Firstly, Specimens were preheated for 30 and 60 cycles, respectively

Then, ratcheting cycling under stress control with stress rate of 100MPa/s

Then, ratcheting cycling under stress control with stress rate of 100MPa/s

Thermal shock testsThermal shock tests

• Specimens were preheated to 500 within 1 hour ℃and held for 10 hours then cooled down to room temperature in furnace

• Then, cycling tests were conducted at room temperature under strain control and stress control, respectively

• Specimens were preheated to 500 within 1 hour ℃and held for 10 hours then cooled down to room temperature in furnace

• Then, cycling tests were conducted at room temperature under strain control and stress control, respectively

Pre-strain cycling testsPre-strain cycling tests

• Specimens were first stretched to 5% and unloaded under strain control with strain rate of 1×10-3 / s

• Then symmetric strain cycling with strain amplitude of 1%

• Specimens were first stretched to 5% and unloaded under strain control with strain rate of 1×10-3 / s

• Then symmetric strain cycling with strain amplitude of 1%

Asymmetric strain cycling tests with strain amplitude of 1% and mean strain of 5% for comparison

Asymmetric strain cycling tests with strain amplitude of 1% and mean strain of 5% for comparison

Strain cycling testsStrain cycling tests

Pre-stress cycling testsPre-stress cycling tests

• Specimens were first stretched to maximum stress 350MPa and unloaded under stress control with stress rate of 100MPa/s

• Then asymmetric stress cycling with stress amplitude of 150MPa and mean stress of 150MPa

• Specimens were first stretched to maximum stress 350MPa and unloaded under stress control with stress rate of 100MPa/s

• Then asymmetric stress cycling with stress amplitude of 150MPa and mean stress of 150MPa

Asymmetric stress cycling tests with stress amplitude of 150MPa and mean stress of 150MPa for comparison

Asymmetric stress cycling tests with stress amplitude of 150MPa and mean stress of 150MPa for comparison

stress cycling testsstress cycling tests

Specimens Pre-stress/MPa Mean stress/MPa Stress amplitude/MPa CyclesLoading

rate(MPa/s)

MT-8

0 150 150 1000 100

350 150 150 1000 100

400 150 150 1000 100

450 150 150 1000 100