Plastic Deformation Behavior of Type 316 Stainless Steel Subject to Out-of-Phase Strain Cycles

1985 ◽  
Vol 107 (4) ◽  
pp. 286-292 ◽  
Author(s):  
Y. Ohashi ◽  
E. Tanaka ◽  
M. Ooka
Keyword(s):  
Stainless Steel ◽  
Kinematic Hardening ◽  
National Laboratory ◽  
Plastic Behavior ◽  
Hardening Model ◽  
Oak Ridge ◽  
316 Stainless Steel ◽  
Plastic Deformation Behavior ◽  
Series Of Experiments ◽  
Tubular Specimens

To elucidate the plastic behavior of metals under out-of-phase strain cycles, a series of experiments was performed on square strain trajectories in a vector space of deviatoric strain by applying combined axial force and torque to thin-walled tubular specimens of type 316 stainless steel. It was confirmed that strain hardening under out-of-phase cycles is much more significant than that under simple cycles. Though the combined isotropic-kinematic hardening model based on the concept of a nonhardening strain region proposed by Ohno gave qualitatively better predictions than the kinematic hardening model by Oak Ridge National Laboratory, there was still a considerable discrepancy between the former theory and the experiment.

Effects of Prior Plasticity on Subsequent Creep of Type 316 Stainless Steel at Elevated Temperature

1986 ◽  
Vol 108 (1) ◽  
pp. 68-74 ◽  
Author(s):  
Y. Ohashi ◽  
M. Kawai ◽  
T. Momose
Keyword(s):  
Plastic Deformation ◽  
Stainless Steel ◽  
Creep Resistance ◽  
Tensile Direction ◽  
316 Stainless Steel ◽  
Plastic Prestraining ◽  
Axial Tensile ◽  
Thin Walled ◽  
Stress States ◽  
Tubular Specimens

Interaction between creep and plastic deformation was studied experimentally for type 316 stainless steel at 650°C, with special emphasis on creep behavior subsequent to plastic prestraining. In combined creep-plasticity experiments, thin-walled tubular specimens were first prestrained plastically in the axial tensile direction, and were subsequently subjected to constant stress creep under various multiaxial stress states with an identical effective stress. Furthermore, the variation in creep resistance due to the plastic prestrain was compared with that due to the same amount of creep prestrain. From the experimental results, it was found that creep resistance was markedly enhanced by the plastic prestrain and that the increase in the creep resistance depended on the amount and relative direction of the plastic prestrain. The creep resistance was increased more markedly by creep prestrain than the same amount of plastic strain.

Fracture Toughness of Stainless Steel Cladding for Evaluation of the Degraded Davis-Besse RPV Head

2006 ◽  
Author(s):  
Randy K. Nanstad ◽  
Mikhail A. Sokolov
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Pressure Vessel ◽  
National Laboratory ◽  
Nuclear Regulatory Commission ◽  
Shear Mode ◽  
Fracture Toughness Test ◽  
Test Results ◽  
Acid Attack ◽  
Oak Ridge

Boric acid attack in the reactor pressure vessel (RPV) head of the Davis-Besse (D-B) nuclear plant led to wastage through the 150-mm low alloy steel head such that the stainless steel cladding was exposed. The Heavy-Section Steel Technology (HSST) Program at Oak Ridge National Laboratory was commissioned by the Nuclear Regulatory Commission to conduct a program of testing and analysis to enable an evaluation of the structural significance of cladding defects found in the wastage cavity of the D-B head. The overall test program consisted of material characterization at 316°C (600°F) of cladding materials, pressure vessel burst tests of cladding discs with and without flaws, and extensive analytical studies. Three different cladding materials were tested and evaluated, one from an unused commercial RPV that was used for the clad-burst experiments, an archival cladding previously used for various experimental and irradiation experiments, and the cladding from the D-B head. This paper compares and discusses the fracture toughness test results conducted with the three claddings, and the fractographic analyses conducted on the clad-burst discs. Comparison of J-resistance curves for the three clad materials shows significant material variability and disparity in the results from two test specimen types. Fractographic examinations of clad-burst discs showed transition from ductile tearing to shear mode of fracture. The relationship of the cladding test results with the clad-burst results is discussed.

scholarly journals Elevated-Temperature Mechanical Properties of an Advanced-Type 316 Stainless Steel1

2000 ◽  
Vol 123 (1) ◽  
pp. 75-80 ◽  
Author(s):  
Charles R. Brinkman
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Elevated Temperature ◽  
National Laboratory ◽  
Low Carbon ◽  
Oak Ridge ◽  
Creep Fatigue ◽  
Nippon Steel Corporation ◽  
Term Creep ◽  
Product Forms

Type 316FR stainless steel is a candidate material for the Japanese demonstration fast breeder reactor plant to be built in Japan early in the next century. Like type 316L(N), it is a low-carbon grade of stainless steel with a more closely specified nitrogen content and chemistry optimized to enhance elevated-temperature performance. Early in 1994, under sponsorship of The Japan Atomic Power Company, work was initiated at Oak Ridge National Laboratory (ORNL) aimed at obtaining an elevated-temperature mechanical-properties database on a single heat of this material. The product form was 50-mm plate manufactured by the Nippon Steel Corporation. Data include results from long-term creep-rupture tests conducted at temperatures of 500 to 600°C with test times up to nearly 40.000 h, continuous-cycle strain-controlled fatigue test results over the same temperature range, limited creep-fatigue data at 550 and 600°C, and tensile test properties from room temperature to 650°C. The ORNL data were compared with data obtained from several different heats and product forms of this material obtained at Japanese laboratories. The data were also compared with results from predictive equations developed for this material and with data available for types 316 and 316L(N) stainless steel.

High Temperature Performance of Cast CF8C-Plus Austenitic Stainless Steel

2010 ◽  
Author(s):  
Philip J. Maziasz ◽  
Bruce A. Pint
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
High Temperature ◽  
Austenitic Stainless Steel ◽  
Gas Turbines ◽  
National Laboratory ◽  
Austenitic Stainless Steels ◽  
Medium Size ◽  
Temperature Oxidation ◽  
Oak Ridge

Covers and casings of small to medium size gas turbines, can be made from cast austenitic stainless steels, including grades such as CF8C, CF3M, or CF10M. Oak Ridge National Laboratory (ORNL) and Caterpillar have developed a new cast austenitic stainless steel, CF8C-Plus, that is a fully-austenitic stainless steel, based on additions of Mn and N to the standard Nb-stabilized CF8C steel grade. The Mn addition improves castability, as well as increasing the alloy solubility for N, and both Mn and N act synergistically to boost mechanical properties. CF8C-Plus steel has outstanding creep-resistance at 600°–900°C, which compares well with Ni-based superalloys like alloys X, 625, 617 and 230. CF8C-Plus also has very good fatigue and thermal fatigue resistance. It is used in the as-cast condition, with no additional heat-treatments. While commercial success for CF8C-Plus has been mainly for diesel exhaust components, this steel can also be considered for gas-turbine and microturbine casings. The purpose of this paper is to demonstrate some of the mechanical properties and update the long-term creep-rupture data, and to present new data on the high-temperature oxidation behavior of these materials, particularly in the presence of water vapor.

Thermal Aging Effect on the Ratcheting Behavior of Pressurized Elbow Pipe

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Caiming Liu ◽  
Dunji Yu ◽  
Waseem Akram ◽  
Xu Chen
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Aging Time ◽  
Thermal Aging ◽  
Aging Temperature ◽  
Aging Process ◽  
Kinematic Hardening ◽  
Aging Effect ◽  
Hardening Model ◽  
User Subroutine

In this study, the ratcheting behaviors of pressurized Z2CN18.10 austenitic stainless steel elbow pipe influenced by the thermal aging process were experimentally investigated in controlled constant internal pressure and reversed in-plane bending after different thermal aging periods (1000 h and 2000 h) at thermal aging temperature of 500 °C. It is shown that the ratcheting behavior of pressured elbow pipe is highly affected by the thermal aging process. The evaluation of ratcheting behavior of pressured elbow pipe was performed using Chen–Jiao–Kim (CJK) kinematic hardening model as a user subroutine of ANSYS. The relationships of yield stress σs and multiaxial parameter χ with thermal aging time were proposed. Ratcheting shakedown boundary of aged elbow pipe was evaluated by CJK model with thermal aging time.

Comparison of Three Microturbine Primary Surface Recuperator Alloys

2009 ◽  
Vol 132 (2) ◽  
Author(s):  
Wendy J. Matthews ◽  
Karren L. More ◽  
Larry R. Walker
Keyword(s):  
Stainless Steel ◽  
Water Vapor ◽  
Oxidation Resistance ◽  
National Laboratory ◽  
Oak Ridge ◽  
Alloy Type ◽  
Oak Ridge National Laboratory ◽  
Oxidation Resistant ◽  
Compositional Changes ◽  
Alloy Depletion

Extensive work performed by Capstone Turbine Corporation, Oak Ridge National Laboratory, and various others has shown that the traditional primary surface recuperator alloy, type 347 stainless steel, is unsuitable for applications above 650°C(∼1200°F). Numerous studies have shown that the presence of water vapor greatly accelerates the oxidation rate of type 347 stainless steel at temperatures above 650°C(∼1200°F). Water vapor is present as a product of combustion in the microturbine exhaust, making it necessary to find replacement alloys for type 347 stainless steel that will meet the long life requirements of microturbine primary surface recuperators. It has been well established over the past few years that alloys with higher chromium and nickel contents than type 347 stainless steel have much greater oxidation resistance in the microturbine environment. One such alloy that has replaced type 347 stainless steel in primary surface recuperators is Haynes Alloy HR-120 (Haynes and HR-120 are trademarks of Haynes International, Inc.), a solid-solution-strengthened alloy with nominally 33 wt % Fe, 37 wt % Ni and 25 wt % Cr. Unfortunately, while HR-120 is significantly more oxidation resistant in the microturbine environment, it is also a much more expensive alloy. In the interest of cost reduction, other candidate primary surface recuperator alloys are being investigated as possible alternatives to type 347 stainless steel. An initial rainbow recuperator test has been performed at Capstone to compare the oxidation resistance of type 347 stainless steel, HR-120, and the Allegheny Ludlum austenitic alloy AL 20–25+Nb (AL 20–25+Nb is a trademark of ATI Properties, Inc. and is licensed to Allegheny Ludlum Corporation). Evaluation of surface oxide scale formation and associated alloy depletion and other compositional changes has been carried out at Oak Ridge National Laboratory. The results of this initial rainbow test will be presented and discussed in this paper.

Ratcheting Simulation of Z2CN18.10 Austenitic Stainless Steel under Pre-Strain Conditions

2016 ◽  
Vol 853 ◽  
pp. 112-116
Author(s):  
Yong Wang ◽  
You Gang Peng ◽  
Xu Chen
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Kinematic Hardening ◽  
Isotropic Hardening ◽  
Good Prediction ◽  
Strain Accumulation ◽  
Modified Model ◽  
Hardening Model ◽  
Ratcheting Strain ◽  
Independent Model

Uniaxial ratcheting behaviors of Z2CN18.10 austenitic stainless steel under both tensile pre-strain (TP) and compressive pre-strain (CP) were experimentally studied at room temperature. The experimental results show that: TP restrains ratcheting strain accumulation of subsequent cycling with positive mean stress; lower level of CP is found to accelerate ratcheting strain accumulation while higher level of CP retards the accumulation. Based on the Ohno-Wang II kinematic hardening rule, rate-independent model, viscoplastic model, isotropic hardening model and a modified model were constructed to describe the ratcheting behaviors under various pre-strain conditions. All the four models gave fairly good prediction on ratcheting strains for various TP. The isotropic hardening model and modified model predicted acceptable ratcheting strain though still showed slight tendency of over prediction.

Developing New Cast Austenitic Stainless Steels With Improved High-Temperature Creep Resistance

2007 ◽  
Author(s):  
Philip J. Maziasz ◽  
John P. Shingledecker ◽  
Neal D. Evans ◽  
Michael J. Pollard
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Creep Strength ◽  
Stainless Steels ◽  
Creep Resistance ◽  
National Laboratory ◽  
Austenitic Stainless Steels ◽  
Alloy Development ◽  
Oak Ridge ◽  
Wide Range

Oak Ridge National Laboratory (ORNL) and Caterpillar have recently developed a new cast austenitic stainless steel, CF8C-Plus, for a wide range of high-temperature applications, including diesel exhaust components and turbine casings. The creep-rupture life of the new CF8C-Plus is over ten times greater than that of the standard cast CF8C stainless steel, and the creep-strength is about double. Another variant, CF8C-Plus Cu/W has been developed with even more creep strength at 750–850°C. The creep-strength of these new cast austenitic stainless steels is close to that of Ni-based superalloys like 617. CF8C-Plus steel was developed in about 1.5 years using an “engineered microstructure” alloy development approach, which produces creep resistance based on formation of stable nano-carbides (NbC) and prevention of deleterious intermetallics (sigma, Laves). CF8C-Plus steel won a 2003 R&D 100 Award, and to date, over 32,000 lb have been produced in various commercial component trials. The current commercialization status of the alloy is summarized.

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