Long Life Fatigue Performance of Stainless Steel

2011 ◽  
Author(s):  
Jussi Solin ◽  
Sven Reese ◽  
Wolfgang Mayinger
Keyword(s):  
Stainless Steel ◽  
Endurance Limit ◽  
Cyclic Stress ◽  
Cyclic Softening ◽  
Fatigue Tests ◽  
Life Extension ◽  
Thermal Transients ◽  
Operation Temperature ◽  
Wide Range ◽  
Material Sample

Fatigue of Niobium stabilized austenitic stainless steel (X6CrNiNb1810 mod) was studied using specimens extracted from a solution annealed and quenched primary piping material sample. This paper reports and discusses results of non-standard experiments to complement previously published test data. The NPP primary piping components spend long times in operation temperature between fatigue cycles originating from thermal transients. This was roughly simulated by fatigue tests periodically interrupted for intermediate annealing in elevated temperature. Fatigue endurance was notably increased when low strain amplitudes were used. The life extension is explained by the cyclic stress strain response. Hardening followed by slow cyclic softening was consistently observed after annealing. It is generally assumed that cumulative accumulation of fatigue damage occurs at a wide range of loading amplitudes. We performed two level and spectrum straining tests combining amplitudes above and below the (Nf > 107) endurance limit. The endurance limit seems to be effective also in variable amplitude loading. In terms of modified Miner rule, even “negative damage” was obtained in two level tests below and above the constant amplitude endurance limit. This behavior is linked to prominent secondary hardening of the steel.

Low-Cycled Fatigue Life of S30408 Stainless Steel at Liquid-Nitrogen Temperature

2018 ◽  
Author(s):  
Yingzhe Wu ◽  
Huaijian Xu ◽  
Qunjie Lu ◽  
Jinyang Zheng ◽  
Ping Xu
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Liquid Nitrogen ◽  
Strain Amplitude ◽  
Hysteresis Loops ◽  
Cyclic Strain ◽  
Liquid Nitrogen Temperature ◽  
Cyclic Stress ◽  
Cyclic Softening ◽  
Fatigue Tests

This paper is concerned with the low-cycled fatigue life of S30408 austenitic stainless steel at 77 K. Strain-controlled low-cycled fatigue tests were performed in a liquid-nitrogen bath covering a strain-amplitude range of 0.4%–1.0%. The role of the reduced temperature is examined during the low-cycled fatigue tests by comparing the fatigue performance to the one at ambient temperature that was obtained in our previous work. It is found that the cryogenic low-cycled fatigue life is significantly improved by a factor of 5–10 in the low strain-amplitude range of 0.4%–0.5%, resulting from the pronounced hardening effect due to the low temperature. However, the cryogenic improvement gradually reduces with the increasing strain-amplitude. At 77 K, the cyclic stress amplitude increases rapidly at the beginning of the fatigue test, and no cyclic softening is found due to the cryogenically constrained movement of the dislocations. The fatigue hysteresis loops and fatigue stress-strain curves shows that the cyclic plastic strain at cryogenic temperature accounts for a limited proportion in the total cyclic strain, and the damage may occurs explosively at the beginning of the cyclic load at 77 K.

Cyclic Mechanical Properties of 16MnR Welded Joint under Constant

2011 ◽  
Vol 197-198 ◽  
pp. 1658-1661
Author(s):  
Ying Xiong ◽  
Han Ying Zheng
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Endurance Limit ◽  
Welded Joint ◽  
Cyclic Softening ◽  
Fatigue Tests ◽  
Test Results ◽  
Control Test ◽  
Strain Control ◽  
Fatigue Endurance

Fatigue tests are carried out for 16MnR welded joint under constant strain control. Test results reveal that 16MnR weld metal exhibits characteristic of cyclic softening and non-masing obviously. The strain–life curve can be best described by the three-parameter equation. It shows the fatigue endurance limit in the heat-affecting zone (HAZ) of welded joint is lower than that in the weld metal.

Fatigue Performance of Stainless Steel in NPP Service Conditions

2012 ◽  
Author(s):  
Jussi Solin ◽  
Sven Reese ◽  
Wolfgang Mayinger
Keyword(s):  
Stainless Steel ◽  
Typical Case ◽  
Fatigue Performance ◽  
Thermal Transients ◽  
Steady State Operation ◽  
Fatigue Data ◽  
Steel Grades ◽  
Material Sample ◽  
Service Conditions ◽  
Effects Of Temperature

Fatigue of Niobium stabilized austenitic stainless steel (X6CrNiNb1810 mod) is studied using specimens extracted from a solution annealed and quenched primary piping material sample. This paper reports and discusses new results complementing the data published in PVP2009 and 2011, where good long life performance was demonstrated and relevance of the new design curve in ASME III was questioned. Effects of temperature and operational loading sequences are in focus here. A typical case with steady state operation between fatigue cycles was roughly simulated in periodically interrupted tests. An extension of fatigue life due to hardening during the holds in elevated temperature was demonstrated and here we show that the hardening effect is generic. It occurs also in isothermal conditions, where straining and holds are both at 325 °C, irrespective of the phase within a cycle, where the hold is introduced, and also for other austenitic steel grades. Fatigue assessment based on standard fatigue data seems to underestimate fatigue performance of materials subjected to typical thermal transients in nuclear piping during operation.

Crack Initiation Under Low-Cycle Multiaxial Fatigue in Type 316L Stainless Steel

1983 ◽  
Vol 105 (2) ◽  
pp. 138-143 ◽  
Author(s):  
B. Jacquelin ◽  
F. Hourlier ◽  
A. Pineau
Keyword(s):  
Stainless Steel ◽  
Crack Initiation ◽  
Low Cycle Fatigue ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Stage I ◽  
Type B ◽  
Strain Behavior ◽  
Number Of Cycles

Low-cycle fatigue tests corresponding to fatigue life range between 103 and 105 cycles were carried out at room temperature on one heat of 316 L austenitic stainless steel. These tests included: (i) reversed tension-compression, (ii) reversed tension-compression with a superimposed steady torque, (iii) pulsated tension-compression with a stress ratio (Rσ) such that −0.5<Rσ<0, (iv) reversed and pulsated tension-compression with a superimposed steady internal pressure. In tests (ii), the torsional ratcheting effect was measured. SEM observations were used to determine the number of cycles corresponding to Stage I crack initiation and the orientation of Stage I microcracks. It was observed that the in-depth growing Type B shear microcracks were most damaging. A simple criterion is proposed Ni=No(Δγp B)α•(σnB)β where Ni is the number of cycles to crack initiation, Δγp B is the range of plastic shear strain on Type B planes, σnB is the maximum normal stress acting on these planes, No,α and β are parameters adjusted from the Manson-Coffin law and reversed cyclic stress-strain behavior.

Fatigue Damage and Life Prediction under Sequential Biaxial Loading

2006 ◽  
Vol 324-325 ◽  
pp. 255-258
Author(s):  
Dan Jin ◽  
Jian Hua Wu ◽  
Xu Chen
Keyword(s):  
Stainless Steel ◽  
Biaxial Loading ◽  
Cyclic Softening ◽  
Fatigue Tests ◽  
304 Stainless Steel ◽  
Loading Mode ◽  
Work Model ◽  
Loading Modes ◽  
Damage Rule ◽  
Additional Hardening

Fatigue tests are conducted on 304 stainless steel and 45C steel under fully reversed strain control conditions with two different loading modes. 45C steel exhibits cyclic softening under each phase loading. While for 304 stainless steel, much additional hardening is observed in out-of-phase loading. The damage values for failure of 45C steel is similar to the previous research, however, 304 stainless steel is not. Fatigue life is predicted based on the linear damage rule, the double linear damage rule, and the plastic work model of Morrow. The damage value is different in the same loading mode for the two materials according to linear damage rule.

Cyclic Deformation of a Modern TiAl Alloy at High Temperatures

2014 ◽  
Vol 891-892 ◽  
pp. 1131-1136 ◽  
Author(s):  
Tomáš Kruml ◽  
Alice Chlupová ◽  
Karel Obrtlík
Keyword(s):  
Lamellar Structure ◽  
Tial Alloy ◽  
Low Cycle Fatigue ◽  
Lamellar Microstructure ◽  
Strain Curve ◽  
Cyclic Stress ◽  
Cyclic Softening ◽  
Fatigue Tests ◽  
Tensile Curve ◽  
Cyclic Straining

Ternary TiAl alloy with 8 at.% Nb and lamellar microstructure is subjected to low cycle fatigue tests at temperatures ranging from room temperature to 800 °C. The aim of the study is to find limit conditions when the microstructure is still stable and to study mechanisms of microstructural degradation when this limit is exceeded. Up to 750 °C, no cyclic softening or hardening is observed and cyclic stress-strain curve follows the tensile curve. Cyclic softening is characteristic for 800 °C. The TEM observation did not reveal any substantial changes in the microstructure due to the cycling up to 700°C. The lamellar structure is altered by cyclic straining at 750 °C and, to a higher extent, at 800°C. In specimens cycled to fracture at 800 °C, the domains without lamellar structure cover about 10% of volume and are almost dislocation free. The destruction of lamellar microstructure is the reason for the marked cyclic softening at 800 °C.

Investigation on Fatigue Properties of Cold Stretched Austenitic Stainless Steel

2011 ◽  
Author(s):  
Cunjian Miao ◽  
Jinyang Zheng ◽  
Li Ma ◽  
Duyi Ye
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Design Method ◽  
Low Cycle Fatigue ◽  
Rolling Direction ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Pressure Vessels ◽  
Fatigue Properties ◽  
Fatigue Design

Cold stretched pressure vessels from austenitic stainless steel (ASS), which are sometimes subjected to alternative loads during operation, have been widely used for storage and transportation of liquefied gases. Understanding how the fatigue properties respond to cold stretching is the basis for establishing fatigue design method of such vessels. This paper involves in the fatigue properties of ASS with 9% plastic deformation by pre-stretching parallel to the rolling direction at room temperature. For this purpose, low-cycle fatigue tests at total strain amplitudes ranging from ±0.4 to 0.8% of cold stretched ASS EN 1.4301 (equivalents include UNS S30400, AISI 304) are performed, while the martensite contents are measured during the fatigue cycles. A comparison study of cyclic stress-strain behavior and fatigue lives is carried out for both cold stretched and solution annealed specimens. Based on the testing results, a S-N curve of cold stretched ASS is obtained, which is compared with the design curves given by the standards such as ASME BPVC VIII-2. These works may help to establish a favorable foundation for the development of fatigue design in cold stretched pressure vessel.

Strain-Based Fatigue Test and Reliability Research of 42CrMo Alloy Steel

2010 ◽  
Vol 97-101 ◽  
pp. 856-860
Author(s):  
Nan Xu ◽  
Xiu Hua Ren ◽  
Wei Qiang Wang
Keyword(s):  
Fatigue Test ◽  
Alloy Steel ◽  
Strain Range ◽  
Cyclic Stress ◽  
Cyclic Softening ◽  
Fatigue Tests ◽  
Range Data ◽  
Stress Range ◽  
Probability Models ◽  
Total Strain Range

The strain-based fatigue tests of 42CrMo alloy steel were conducted by controlling six sets of total strain range, and stress range data was obtained under each strain range. The results of fatigue test revealed that fatigue performance of 42CrMo alloy steel was of tremendous dispersivity all though materials were strictly chosen, heat-treated and machined. Cyclic stress-strain (CSS) curves were compared with monotonic tensile curve, which showed that 42CrMo alloy steel quenched and tempered was a kind of cyclic softening material. Evaluation results revealed that LND was the best probability function to describe cyclic stress of strain fatigue for 42CrMo steel. Cyclic stress range under the median and high probability was evaluated by means of stochastic performance probability models.

Fatigue Performance of Stabilized Austenitic Stainless Steels: Experimental Investigations Respecting Operational Relevant Conditions Like Temperature and Hold Time Effects

2013 ◽  
Author(s):  
Jussi Solin ◽  
Sven Reese ◽  
H. Ertugrul Karabaki ◽  
Wolfgang Mayinger
Keyword(s):  
Stainless Steel ◽  
Hold Time ◽  
Austenitic Stainless Steels ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Normal Operation ◽  
Experimental Investigations ◽  
Fatigue Assessment ◽  
Thermal Transients ◽  
Loading Patterns

Experimental research on fatigue performance of niobium stabilized stainless steel (1.4550, X6CrNiNb1810mod) relevant for German NPP primary piping demonstrated good long life performance. Fatigue tests periodically interrupted for holds indicated time and temperature dependent hardening during holds at 25°C to 325°C. Notable extension of fatigue life was measured when loading patterns consist of cyclic deformation in lower temperatures than hold annealing. Many NPP piping thermal transients separated by normal operation belong to this category and fatigue assessment based on standard fatigue data seems to underestimate fatigue endurance. Further results for stabilized stainless steel in air at various temperatures will be provided. A parallel paper will deliver unpublished data in PWR water. The influences of temperature and loading pattern will be discussed aiming to improve fatigue assessment of plant components and to reduce confusion concerning applicability of international design codes.

Cyclic Softening of Cu-Ni-Si Alloy Single Crystals under Low-Cycle Fatigue

2010 ◽  
Vol 654-656 ◽  
pp. 1287-1290 ◽  
Author(s):  
Toshiyuki Fujii ◽  
Hiroshi Kamio ◽  
Yoshifumi Sugisawa ◽  
Susumu Onaka ◽  
Masaharu Kato
Keyword(s):  
Plastic Strain ◽  
Single Crystals ◽  
Low Cycle Fatigue ◽  
Strain Curve ◽  
Electron Microscopic Observation ◽  
Cyclic Hardening ◽  
Cyclic Stress ◽  
Cyclic Softening ◽  
Fatigue Tests ◽  
Electron Microscopic

Cu-2.2wt%Ni-0.5wt%Si alloy single crystals were grown by the Bridgman method and aged at 723 K for 10 h to form Ni2Si precipitates. Fully reversed tension-compression fatigue tests were conducted on the aged single crystals with a single slip orientation under constant plastic-strain amplitudes at room temperature. Cyclic softening occurred at plastic-strain amplitudes between 2.5x10-4 and 2.5x10-2. Using the maximum stress amplitude in each cyclic hardening/softening curve, a pseudo cyclic stress-strain curve (CSSC) was obtained. The CSSC was found to exhibit a plateau region with a stress level of about 167 MPa. Transmission electron microscopic observation revealed the formation of persistent slip bands (PSBs) in the plateau regime. It was found that the Ni2Si precipitate particles were intensively sheared by glide dislocations within the PSBs and were eventually re-dissolved into the Cu matrix. The macroscopic cyclic softening can be attributed to the local softening induced by the re-dissolution of the Ni2Si particles in the PSBs.

Sign in / Sign up

Export Citation Format

Share Document