Ultrasonic Inspection of Austenitic Stainless Steel Weldments—Our Experiences

1983 ◽  
Vol 15 (3) ◽  
pp. 91
Author(s):  
V. C. Padaki ◽  
P. Barat ◽  
Baldev Raj ◽  
D. K. Bhattacharya
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Ultrasonic Inspection

Research on Ultrasonic Inspection of Cast Austenitic Stainless Steel Piping

2012 ◽  
Author(s):  
Kazunobu Sakamoto ◽  
Takashi Furukawa ◽  
Ichiro Komura ◽  
Yoshinori Kamiyama ◽  
Tsuyoshi Mihara
Keyword(s):  
Stainless Steel ◽  
Wave Propagation ◽  
Austenitic Stainless Steel ◽  
Ultrasonic Wave ◽  
Research Program ◽  
Ultrasonic Inspection ◽  
Piping System ◽  
Pressurized Water ◽  
Ultrasonic Wave Propagation ◽  
Steel Piping

Japan Nuclear Energy Safety Organization (JNES) has been carrying out the research program entitled “Nondestructive Inspection Technologies for the Cast Stainless Steel Piping” since 2009FY to comprehend the unique ultrasonic wave propagation in the Cast Austenitic Stainless Steel (CASS) and to confirm detection and sizing capability for cracks in the material by currently available ultrasonic testing techniques. The research is also intended to provide inspection staff with the fundamental information of ultrasonic wave propagation in CASS, for educational purpose. In this research program, specimens whose material, size, dimension and welding method are identical to the main coolant piping system in Japanese pressurized water reactors (PWRs) are examined. Results from the study on the capability for inspection of CASS and the unique wave propagation phenomena such as beam skewing are discussed in this paper.

A New Ultrasonic Inspection Technique for Flaw Depth Sizing Based on Short Path of Diffraction

2007 ◽  
Author(s):  
Shan Lin ◽  
Hiroyuki Fukutomi ◽  
Takashi Ogata
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Stress Corrosion ◽  
Incident Wave ◽  
Short Path ◽  
Ultrasonic Inspection ◽  
The Other ◽  
New Technique ◽  
Back Wall ◽  
Flaw Sizing

This paper describes a new tip diffraction technique, short path of diffraction (SPOD), for accurate depth sizing of flaws on the surface opposite to the inspection surface in which a set of an angle beam and a longitudinal 0-degree transducers is used as a transmitter and a receiver. In this technique, flaw depth is just calculated from the time difference between two echoes of a longitudinal diffracted wave at the tip of a flaw, which arises after an incident wave from the angle beam transducer impinges on the flaw. One echo is related to a wave traveling directly from the tip to the receiver, and the other is a wave which is reflected at the back wall and subsequently travels to the receiver. The two echoes are detected by the longitudinal 0-degree transducer located right above the flaw. Incident angles and incident points have no effect on determining flaw depth in this technique, therefore, more accurate and efficient flaw sizing becomes possible for the proposed technique. The new technique will be demonstrated by applying to depth sizing of slits and stress corrosion cracks which are machined into welded specimens made from austenitic stainless steel.

Probabilistic Models of Reliability of Cast Austenitic Stainless Steel Piping

2012 ◽  
Author(s):  
Haiyang Qian ◽  
David Harris ◽  
Timothy J. Griesbach
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Tensile Properties ◽  
Power Plants ◽  
Probabilistic Models ◽  
Probabilistic Approach ◽  
Ultrasonic Inspection ◽  
Delta Ferrite ◽  
Thermal Embrittlement

The concern of toughness reduction due to thermal embrittlement of cast austenitic stainless steel (CASS) piping is increasing as nuclear power plants age. Because of the large and variable grain size of the CASS materials, the ultrasonic inspection (UT) difficulties of the CASS components increases concerns regarding their reliability. Another added concern is the presence of potential defects introduced during the casting fabrication process. The possible presence of defects and difficulty of inspection complicate the development of programs to manage the risk contributed by these potentially degraded components. Experiments have been performed in the past to evaluate the effect of thermal embrittlement on tensile properties and fracture toughness as functions of time, temperature, composition, and delta ferrite content, but considerable scatter has been shown in the results among the important variables. A probabilistic approach is proposed for the evaluation of the aging effect based on the scatter in material correlations, difficulty of inspection and presence of initial defects. The purpose of this study is to describe a probabilistic fracture mechanics analysis approach for the determination of the maximum allowable flaw sizes in CASS piping components in commercial power reactors, using Monte Carlo simulation. Attention is focused on fully embrittled CF8M material, and the probability of failure for a given crack size, load and composition is predicted considering scatter in tensile properties and fracture toughness (fracture toughness is expressed as a crack growth resistance relation in terms of J-Δa). The correlation between the reduced toughness and increased tensile properties due to thermal embrittlement is also included in the analysis. This paper presents results for CF8M to demonstrate the sensitivity of key input variables on the most severely embrittled material. The output of this study is the flaw size (length and depth) that will fail with a given probability as a function of load and geometry.

Phased Array Ultrasonic Inspection Technique for Cast Austenitic Stainless Steel Parts of Nuclear Power Plants

2016 ◽  
Author(s):  
Setsu Yamamoto ◽  
Jun Semboshi ◽  
Azusa Sugawara ◽  
Makoto Ochiai ◽  
Kentaro Tsuchihashi ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Ultrasonic Testing ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Phased Array ◽  
Ultrasonic Inspection ◽  
Inspection Time ◽  
Accuracy Measurement

For safety operation of nuclear power plants, soundness assurance of structures has been strongly required. In order to evaluate properties of inner defects at plant structures quantitatively, non-destructive inspection using ultrasonic testing (UT) has performed an important role for plant maintenances. At nuclear power plants, there are many structures made of cast austenitic stainless steel (e.g. casings, valve gages, pipes and so on). However, UT has not achieved enough accuracy measurement at cast stainless steels due to the noise from large grains. In order to overcome the problem, we have developed comprehensively analyzable phased array ultrasonic testing (PAUT) system. We have been noticing that dependency of echo intensity from defect is different from grain noises when PAUT conditions (for example, ultrasonic incident angles and focal depths) were continuously changed. Analyzing the tendency of echoes from comprehensive PAUT conditions, defect echoes could be distinguished from the noises. Meanwhile, in order to minimize the inspection time on-site, we have developed the algorithms and the full matrix capture (FMC) data acquisition system. In this paper, the authors confirmed the detectability of the PAUT system applying cast austenitic stainless steel (316 stainless steel) specimens which have sand-blasted surface and 3 slits which made by electric discharge machining (EDM).

scholarly journals Artificial Neural Network Modelling for Prediction of SNR Effected by Probe Properties on Ultrasonic Inspection of Austenitic Stainless Steel Weldments

2018 ◽  
Vol 16 (1) ◽  
pp. 511-515
Author(s):  
Memduh Kurtulmuş
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Longitudinal Wave ◽  
Ultrasonic Inspection ◽  
Probe Frequency ◽  
Probe Angle ◽  
Ann Models ◽  
Angle Probe

AbstractMany austenitic stainless steel components are used in the construction of nuclear power plants. These components are joined by different welding processes, and radiation damages occur in the welds during the service life of the plant. The plants are inspected periodically with ultrasonic test methods. Many ultrasonic inspection problems arise due to the weld metal microstructure of austenitic stainless steel weldments. The present research was conducted in order to describe the affects of probe angle and probe frequency of both transversal and longitudinal wave probes on detecting the defects of austenitic stainless steel weldments. Feed forward back propagation artificial neural network (ANN) models have been developed for predicting signal to noise ratio (SNR) of transversal and longitudinal wave probes. Input variables that affect SNR output in these models are welding angle, probe angle, probe frequency and sound path. Of the experimental data, 80% is used for a training dataset and 20% is used for a testing dataset with 10 neurons in hidden layers in developed ANN models. Mean absolute error (MAE) and mean absolute percentage error (MAPE) types are calculated as 0.0656 and 16.28%, respectively, to predict performance of ANN models in a transversal wave probe. In addition, MAE and MAPE are calculated as 0.0478 and 18.01%, respectively, for performance in a longitudinal wave probe.

Some aspects of the defect structure in an austenitic stainless steel

1978 ◽  
Vol 36 (1) ◽  
pp. 314-315
Author(s):  
R. Gonzalez ◽  
L. Bru
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Cellular Structures ◽  
Total Strain Amplitude ◽  
Total Deformation ◽  
Density Of Dislocations ◽  
Planar Arrays ◽  
Stacking Fault Tetrahedra ◽  
Distribution Of Dislocations ◽  
Very High

The analysis of stacking fault tetrahedra (SFT) in fatigued metals (1,2) is somewhat complicated, due partly to their relatively low density, but principally to the presence of a very high density of dislocations which hides them. In order to overcome this second difficulty, we have used in this work an austenitic stainless steel that deforms in a planar mode and, as expected, examination of the substructure revealed planar arrays of dislocation dipoles rather than the cellular structures which appear both in single and polycrystals of cyclically deformed copper and silver. This more uniform distribution of dislocations allows a better identification of the SFT.The samples were fatigue deformed at the constant total strain amplitude Δε = 0.025 for 5 cycles at three temperatures: 85, 293 and 773 K. One of the samples was tensile strained with a total deformation of 3.5%.

A TEM microscopical investigation of the magnetic domain structure of a metastable austenitic stainless steel

1994 ◽  
Vol 52 ◽  
pp. 696-697
Author(s):  
G. Fourlaris ◽  
T. Gladman
Keyword(s):  
Tensile Strength ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Cold Rolling ◽  
Solution Treatment ◽  
Magnetic Domain ◽  
High Strength ◽  
Medium Carbon Steel ◽  
Magnetic Characteristics ◽  
Metastable Austenitic Stainless Steel

Stainless steels have widespread applications due to their good corrosion resistance, but for certain types of large naval constructions, other requirements are imposed such as high strength and toughness , and modified magnetic characteristics.The magnetic characteristics of a 302 type metastable austenitic stainless steel has been assessed after various cold rolling treatments designed to increase strength by strain inducement of martensite. A grade 817M40 low alloy medium carbon steel was used as a reference material.The metastable austenitic stainless steel after solution treatment possesses a fully austenitic microstructure. However its tensile strength , in the solution treated condition , is low.Cold rolling results in the strain induced transformation to α’- martensite in austenitic matrix and enhances the tensile strength. However , α’-martensite is ferromagnetic , and its introduction to an otherwise fully paramagnetic matrix alters the magnetic response of the material. An example of the mixed martensitic-retained austenitic microstructure obtained after the cold rolling experiment is provided in the SEM micrograph of Figure 1.

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