Download or read book Evaluation of Ductile to Brittle Transition Temperature by Reference Temperature T0 Approach at Higher Loading Rates for a Mod 9Cr 1Mo Steel written by A. Moitra and published by . This book was released on 2014 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: To evaluate the ductile-to-brittle transition temperature of ferritic-martensitic steels, the ASTM E1921-based reference temperature (T0) approach has now been widely recognized; however, until now, the standard restricts itself to static/quasi-static loading rates. It is well recognized that the flow stress of rate-sensitive material increases with the strain rate, and thus it is imperative that the increase in loading rate would lead to limited plasticity-induced brittleness, reflected in higher T0. There have been efforts in the literature for developing empirical correlations to derive T0 at higher loading rates from T0 at quasi-static loading rates or vice versa. However, there is a need to experimentally evaluate the T0 at higher loading rates, especially for the 9Cr-1Mo family of steels, proposed to be used as wrapper material in the upcoming commercial liquid-sodium-cooled fast breeder reactors in India. The present study is directed toward determining T0 for Mod.9Cr-1Mo steel at loading rates of 1.12, 3, and 5 m/s.

Download or read book A Closer Look at Effects of the Loading Rate on Fracture Toughness in the Ductile to Brittle Transition Regime of a Ferritic Steel written by Hans-Jakob Schindler and published by . This book was released on 2015 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: An increased loading rate causes not only a shift of the ductile-to-brittle transition curve, but also a slight change of the shape of this curve. The latter tends to become steeper as the loading rate increases. This effect was observed even at loading rates that are considered to be quasi-static according to ASTM E1921-13: Standard Test Method for Determination of Reference Temperature, T0, for Ferritic Steels in the Transition Range, Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2013. Actually, the coefficient 0.019 in the exponent of the MC turned out to be substantially higher at elevated loading rates. This means that a basic assumption of the evaluation procedure of ASTM E1921 is not met, which leads to an increased uncertainty of T0 or T0,x, respectively. This effect of is most pronounced in testing at elevated loading rates using the single-temperature option. An improved method to determine the reference temperature is proposed, where the exponent in the median transition curve in ASTM E1921 is considered to be an open parameter. The resulting reference temperatures, denoted as T100 andT100,x, respectively, are expected to be more accurate than standard T0, which is confirmed by comparison with experimental data. Furthermore, the validity requirements for T100 are less restrictive and more suitable than those in ASTM E1921, since they do not depend on the outcome of the tests. Based on the improved data, an improved estimation formula for the rate-induced shift of T0 is derived. Suggestions are made for improvement of ASTM E1921.

Download or read book Steel Transition Fracture Toughness Reference Temperature Determination written by and published by . This book was released on 1998 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantitative measurements of cracking resistance are needed to assess the risk of brittle fracture under service conditions in warships. This requires laboratory toughness testing at the minimum service temperature and at loading rates equivalent to hull impact events such as wave slamming and minor collisions. A technique has recently been standardized for determining the fracture toughness of ferritic marine construction steels and welds in the brittle-ductile transition range. In this technique, toughness transition curves are generated statistically from the analysis of toughness data populations using a master curve concept. This report describes a preliminary series of tests to evaluate 350WT steel plate using this approach and to establish the degree to which such a procedure will provide useful data for structural integrity analyses.

Download or read book Dynamic Fracture Toughness Measurements in the Ductile to Brittle Region Using Small Specimens written by RE. Link and published by . This book was released on 2003 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic fracture toughness of a reactor pressure vessel steel was investigated using small specimens. Precracked Charpy-size SE(B) specimens and circumferentially cracked round bars (CRB) loaded in tension were used to investigate the dynamic fracture toughness of an A533, Gr. B steel plate within the ductile-brittle transition region. The specimens used in this investigation were removed from the broken halves of conventional 4T C(T) specimens that had been utilized in a previous investigation of the dynamic fracture toughness of this material. Crack-tip loading rates in excess of 104 MPa-m1/2/s were achieved in the current tests. Multiple specimens were tested at each temperature in order to permit the determination of the reference temperature, T0. A fracture toughness scaling model for the circumferentially cracked round bar developed by Sciabetta was used to account for the loss of constraint in this specimen. A master curve approach was used to characterize the dynamic toughness in the ductile-brittle region. The shift in transition temperature was compared to a model for the strain rate dependence of T0 developed by Wallin. The shift in transition temperature of the CRB specimen was accurately predicted by the model. The CRB specimen and the dynamic SE(B) specimens gave good results considering the material inhomogeneity typical of the plate tested.

Download or read book On Setting Testing Rate Limitations for the Master Curve Reference Temperature To of ASTM E 1921 written by JA. Joyce and published by . This book was released on 2006 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tests conducted to identify the ductile to brittle transition in ferritic steels have historically been conducted at elevated loading rates since it was understood that this transition was very dependent on the loading rate. By testing at an elevated loading rate, the researcher identified an upper bound transition temperature that could be expected to be conservative for most structural applications. In the development of the Master Curve procedure and the To reference temperature of ASTM E 1921, Standard Test Method for Determination of Reference Temperature, To, for Ferritic Steels in the Transition Range, allowable test rates were restricted to the "quasi-static" regime typical of elastic-plastic fracture toughness standards like E 1290 and E 1820. Since this standard was developed primarily for nuclear pressure vessels in which even a pressurized thermal shock event results in relatively slow loading rates because of the large size of the structures involved, the limitation to rather slow loading rates was not considered to be important. The loading rate allowed by E 1921-03 encompasses approximately two orders of magnitude for dK/dt with dK/dt ? 1.0 Mpa ?m/s, but the standard has not required the direct measurement of the loading rate or the reporting of the actual loading rate. The expectation is that for such a "quasi-static" loading rate the resulting To is not strongly dependent on the loading rate, and the result can be used in "quasi-static" applications without adjustment for the likely difference between test and application loading rates. Recently Hall and Yoon [1] and Wallin [2] have reported results that appear to show that tests conducted over the range of loading rates allowed by E 1921 can result in a difference in the resulting reference temperature of 30 to 50 °C. Wallin has suggested [3] reducing the allowable range of testing to a very narrow factor of 4 centered on dK/dt = 1.0 MPa?m/s, or requiring a correction procedure to account for the test machine rate used.

Download or read book Dynamic Initiation Fracture Toughness of a Pressure Vessel Steel in the Transition Region written by SM. Graham and published by . This book was released on 1999 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic fracture toughness of an ASTM A533, Grade B steel plate was determined at several temperatures in the ductile-brittle transition region. Crack-tip loading rates ranged from approximately 103 to 105 MPa?m/s. The fracture toughness was shown to decrease with increased loading rate. The dynamic fracture toughness was compared with results from previous investigations and it was shown that the decrease in toughness due to increased loading rate at the highest test temperature was not as severe as reported in previous investigations. It was also shown that the reference temperature, T0, was a better index of the fracture toughness vs. temperature relationship than the nil-ductility temperature, RTNDT for this material.

Download or read book Considering the Statistical Distribution of Dynamic Fracture Toughness Data and the Actual Loading Rate at Fracture Initiation When Applying ASTM E1921 at Elevated Loading Rates written by U. Mayer and published by . This book was released on 2016 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: ASTM E1921-15a describes the determination of the reference temperature T0,X for the loading rate X for ferritic steels in the transition range, where X is the order of magnitude of the average loading rate of the tests evaluated. Because this rate is defined for the linear-elastic part of a test only, the definition of the loading rate, valid for tests showing not only linear-elastic but also plastic behavior, is important. In a research project investigating the correlation of dynamic crack initiation and crack arrest funded by the German government, tests at -20°C on specimens of 22 NiMoCr 3 7 steel (A 508 Cl.2) were performed with different specimen geometry and loading devices in the range from 105 MPa?m s-1 to 3 x 106 MPa?m s-1. Evaluation according to ASTM E1921 shows differences of up to 30 K in T0,X obtained from linear-elastic test series and T0,X obtained from elastic-plastic test series with comparable dK/dt. New results were obtained in the current follow-up joint IWM-MPA project from test series at a loading rate of 5 x 105 MPa?m s-1. Results from tests with 1T C(T)-specimen at various test temperatures in the transition region are presented, analyzed, and reference temperature T0,5 is evaluated. The statistical distribution of the determined dynamic fracture toughness values KId resp., KJc,d and the determination of the characteristic loading rate in the case of elastic-plastic tests is discussed. This analysis shows the need of modifications of the standard evaluation method in ASTM E1921, if used for tests at elevated loading rate. The assumed statistical distribution has to be adapted and the actual loading rate at fracture initiation has to be taken into account. Suggestions for the considerations and requirements for the evaluation of data determined at elevated loading rates are presented.

Download or read book Analysis of Ductile Brittle Transition Temperatures for Controlled Rolled Microalloyed C Mn Based Steels written by R. W. Armstrong and published by . This book was released on 1988 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Charpy V-notch ductile-brittle transition temperatures reported for a conventional carbon manganese steel and for several controlled-rolled microalloyed steels are compared with transition temperatures computed on a dislocation model basis. The computed transition temperature, Tc, is specified by equating the tensile cleavage fracture stress and the effective yield stress at the Charpy V-notch. Increased friction stress resistances to dislocation movement provided by solutes, precipitates, and other dislocations raise the yield stress and, thereby, increase Tc. A residual dislocation based friction stress resistance occurs within untransformed ferrite grains (that is, the ferrite present at the rolling temperature) when finish rolling is done in the austenite-ferrite region. Grain size refinement normally lowers Tc because the cleavage stress is increased to a greater extent than is the yield stress. Keywords: Ductile-brittle transition temperature, C-Mn steel, Carbide plate effects. (jes).

Download or read book Failure Analysis of Heat Treated Steel Components written by Lauralice de Campos Franceschini Canale and published by ASM International. This book was released on 2008 with total page 651 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Strain Rate Effects on the Ductile Brittle Transition in Steels written by GA. Knorovsky and published by . This book was released on 1985 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: A recently implemented fracture control plan for structural steel high-way bridges makes use of a linear relation to describe the effect of strain rate on the ductile/brittle transition temperature as a function of yield strength. Literature data show that the predictions of the aforementioned relation are not general. An alternative analysis is offered along with a qualitative model for understanding the phenomenon. Results of an experimental program investigating microstructural effects on the ductile/brittle strain rate dependence are also presented. The results exhibit linear behavior of ?Tdb versus ??/?, where ?Tdb is the transition temperature shift, ? is the yield stress, and ?? is the change in yield stress caused by strain rate. The magnitude of the temperature shift, however, is dependent upon the test specimen used. Factors discussed include microstructure, type of test specimen (Charpy V-notch, nil ductility temperature [NDT], modified NDT, or compact toughness), crack initiation versus crack propagation, and implications for regulatory bodies.

Download or read book Development of a Multiple Linear Regression Model to Estimate the Ductile Brittle Transition Temperature of Ferritic Low Alloy Steels Based on the Relationship Between Small Punch and Charpy V Notch Tests written by ML. Saucedo-Muñoz and published by . This book was released on 2000 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The transition temperatures of Cr-0.5Mo, Cr-Mo, and Cr-Mo-V steels were determined using the Charpy V-notch (CVN) and the small punch (SP) tests. It was confirmed that there was a linear correlation between the transition temperature of ductile-brittle behavior determined by the Charpy V-notch test and that obtained from the small punch test. However, the estimation of CVN transition temperature by means of this linear equation is not completely reliable because of the large experimental scatter of data. In order to improve the reliability of the transition temperature estimation, a multiple linear regression (MLR) analysis was conducted to evaluate the effect of different variables of the manufacturing process and service conditions. This analysis permitted the determination of the following regression equation: CVNDBTT=1.35SPDBTT-0.84x103d-1/2+326. This equation enables one to assess more accurately the transition temperature corresponding to the Charpy V-notch test using that of the small punch test and the austenitic grain size, expressed by d-1/2.

Download or read book The Effect of Alloying on Brittle ductile Transition Temperature of 9 Cr 1 Mo Ferritic Steel written by Hendra Indrawirawan and published by . This book was released on 1982 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Assessing the Loading Rate for a Fracture Toughness Test in the Ductile to Brittle Transition Region written by Enrico Lucon and published by . This book was released on 2008 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: For fracture toughness tests in the ductile-to-brittle transition region, ASTM E1921-05 requires specimens to be loaded using a loading rate dK/dt between 0.1 and 2 MPa?m/s during the initial elastic portion. It has been proposed that the standard allow testing at higher loading rates, including precracked Charpy specimens tested on an instrumented pendulum machine (impact toughness tests). The revised standard would require test results (KJc or To) to be reported along with the relevant loading rate, and should therefore provide guidance on how to assess the value of dK/dt in a relatively simple but reliable manner. Various options for measuring the loading rate have been investigated in this paper for several fracture toughness tests performed at different loading rates (quasi-static, dynamic, and impact). For each loading rate, three different toughness levels have been considered: low, medium, and high. Three considerably different materials have been selected: two RPV steels (JRQ, JSPS) and a ferritic/martensitic 9 % chromium steel (EUROFER97). It is found that the preferable option is given by the ratio between KJc and time at the onset of cleavage, whereas the elastic value Kel/tel or the average dK/dt can be used when partial unloadings are performed.

Download or read book Evaluation of the Effect of Biaxial Loading on the To Reference Temperature Using a Cruciform Specimen Geometry written by JA. Joyce and published by . This book was released on 2005 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of 12 cruciform geometry fracture toughness specimens has recently been tested using A533B base plate obtained from the decommissioned Shoreham plant pressure vessel. Specimens were tested at -100°C, placing them in the lower ductile to brittle transition of this ferritic structural steel. The overall objective of this work is to compare the results of these biaxial cruciform tests to the results of standard and shallow crack fracture toughness tests to assess the effect of biaxial loading on the measured master curve and the To reference temperature as defined by ASTM E 1921. Previous work done at Oak Ridge National Laboratory (ORNL) appeared to demonstrate an increase in the To reference temperature due to the presence of the biaxial stress field established in the cruciform test geometry. Because of the cost of the ORNL tests, only a few specimens could be run, and full statistical support of the "biaxial effect" could not be demonstrated. A second goal is to demonstrate that smaller size specimens, and hence lower cost tests, can be used to evaluate the magnitude of the biaxial effect in nuclear reactor pressure vessel materials. This report presents a brief overview of the test procedure, presents the test results, and compares the results to the database available on standard and shallow crack fracture toughness results available for the Shoreham plate material.

Download or read book Ductile to Brittle Transition Characterization Using Surface Crack Specimens Loaded in Combined Tension and Bending written by JA. Joyce and published by . This book was released on 1997 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface cracked tension specimens of ASTM A515, Grade B steel plate were tested to failure in the ductile-to-brittle transition region. Two different specimen configurations were used: one configuration was loaded in tension except for the natural bending resulting from the presence of the surface crack, the second configuration had an offset test section and was pin-loaded to provide a strong bending component in addition to the tension load. For each configuration, at least seven repeat tests were conducted at each of two temperatures. All specimens failed by cleavage and the critical J-integral, Jc, was obtained using three-dimensional finite element analysis of the specimen. The FEM analysis was validated by comparison with experimental strain gage and displacement measurements taken during the tests. The results were compared with previous fracture toughness measurements on the same plate using 2T SE(B) specimens and surface cracked bend SC(B) specimens. The present results exhibited the expected elevation in fracture toughness and downward shift in the transition temperature compared to the highly constrained, deeply cracked SE(B) specimens. The master curve approach was used to characterize the transition curves for each specimen geometry and the shift in the transition temperature was characterized by the associated reference temperature.

Download or read book Development of Small Punch Tests for Ductile Brittle Transition Temperature Measurement of Temper Embrittled Ni Cr Steels written by J-M Baik and published by . This book was released on 1986 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Small punch tests were developed to determine the ductile-brittle transition temperature of nickel-chromium (Ni-Cr) steels having various degrees of temper embrittlement and various microstructures. It was found that the small punch test clearly shows the ductile-brittle transition behavior of the temper-embrittled steels. The measured values were compared with those obtained from Charpy impact and uniaxial tensile tests. The effects of punch tip shape, a notch, and the strain rate on the ductile-brittle transition behavior were examined. It was found that the combined use of a notch, high strain rates, and a small punch tip strongly affects the ductile-brittle transition behavior. Considerable variations in the data were observed when the small punch tests were performed on coarse-grained steels. Several factors controlling embrittlement measurements of steels are discussed in terms of brittle fracture mechanisms.

Download or read book Estimation Uncertainty in the Determinatin of the Master Curve Reference Temperature written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Master Curve Reference Temperature, T0, characterizes the fracture performance of structural steels in the ductile-to-brittle transition region. For a given material, this reference temperature is estimated via fracture toughness testing. A methodology is presented to compute the standard error of an estimated T0 value from a finite sample of toughness data, in a unified manner for both constant temperature and multiple temperature test methods. Using the asymptotic properties of maximum likelihood estimators, closed-form expressions for the standard error of the estimate of T0 are presented for both test methods. This methodology includes statistically rigorous treatment of censored data, which represents an advance over the current ASTM E1921 methodology. Through Monte Carlo simulations of realistic constant temperature and multiple temperature test plans, the recommended likelihood-based procedure is shown to provide better statistical performance than the methods in the ASTM E1920 standards.