Fracture Mechanics at Elevated Loading Rates in the Ductile to Brittle Transition Region

2017 ◽  
Author(s):  
Uwe Mayer ◽  
Thomas Reichert ◽  
Johannes Tlatlik
Keyword(s):  
Fracture Toughness ◽  
Dynamic Loading ◽  
Dynamic Fracture ◽  
Master Curve ◽  
Crack Arrest ◽  
Dynamic Fracture Toughness ◽  
Fracture Probability ◽  
High Rate ◽  
Loading Rates ◽  
Static Conditions

The rate-dependent reference temperature T0,x characterizes the fracture toughness of ferritic steels at the onset of cleavage. Fracture toughness values KJc,d were determined according to the Annex A1 of ASTM E1921 [1] which refers to the high rate annexes A14 and A17 of ASTM E1820 [2]. Results of extensive dynamic fracture toughness experiments at various loading rates, temperatures, specimen types and sizes revealed shortcomings in the transferability of the shape of the Master Curve under quasi-static conditions to elevated loading rates. In particular, the quasi-static Master Curve predicts lower fracture toughness values towards higher temperatures than experimentally observed under dynamic loading causing a steeper Master Curve shape. Fractographic examinations proved the relevance of local crack arrest under dynamic loading conditions, which is consistent with the view of the parallelism of dynamic fracture probability and probability of arrest.

IAEA Coordinated Research Project on Master Curve Approach to Monitor Fracture Toughness of RPV Steels: Effect of Loading Rate

2007 ◽  
Author(s):  
Hans-Werner Viehrig ◽  
Enrico Lucon
Keyword(s):  
Fracture Toughness ◽  
Master Curve ◽  
Loading Rate ◽  
Crack Arrest ◽  
Dynamic Fracture Toughness ◽  
Current Status ◽  
Research Project ◽  
Topic Area ◽  
Loading Rates ◽  
Data Assessment

In the final evaluation for the application of the Master Curve in the IAEA Coordinated Research Project Phase 5 (CRP-5), one of the areas which was identified as needing further work concerned the effects of loading rate on the reference temperature To up to impact loading conditions. This subject represents one of the three topic areas within the current CRP-8. The effect of loading rate can be broken down into two distinct aspects: 1) the effect of loading rate on the Master Curve To values for loading rates within the specified in ASTM E1921-05 for quasi-static loading (0.1–2 MPa√m/s); 2) the effect of loading rate on To values for higher loading rates, including impact conditions using instrumented precracked Charpy (PCC) specimens. The new CRP includes both aspects, but primarily focuses on the second element of loading rate effects, i.e. loading rates above 2 MPa√m/s. These issues are investigated within the topic area #2 of CRP-8 (Loading Rate Effect). The mandatory portion of this topic area required participation in a round-robin exercise (RRE) to validate the application of the Master Curve approach to PCC specimens tested in the ductile-to-brittle transition region using an instrumented pendulum (10 tests per participant on the JRQ material). The current status of the RRE is presented in [1]. The non-mandatory portion of this topic area consists in providing Master Curve data obtained at different loading rates on various RPV steels, in order to assess the loading rate dependence of To and compare it with an empirical model proposed by Wallin. Moreover, additional topics will be addressed, such as: • comparison of results from unloading compliance and monotonic loading in the quasi-static range; • estimation of fracture toughness from Charpy V-notch data; • assessment of crack arrest properties from instrumented Charpy results; • effect of irradiation on the relationship between static and dynamic fracture toughness.

Determination of Dynamic Fracture Toughness Using Strain Measurement

2004 ◽  
Vol 261-263 ◽  
pp. 313-318 ◽  
Author(s):  
Duck Hoi Kim ◽  
Soon Il Moon ◽  
Jae Hoon Kim
Keyword(s):  
Fracture Toughness ◽  
Dynamic Fracture ◽  
Strain Measurement ◽  
Charpy Impact ◽  
Dynamic Fracture Toughness ◽  
High Rate ◽  
Energy Methods ◽  
Inertial Effects ◽  
Optimum Response

By contrast with static fracture toughness determination, the methodology for dynamic fracture toughness characterization is not yet standardized and appropriate approaches must be devised. The accurate determination of the dynamic stress intensity factors must take into account inertial effects. Most methods for dynamic fracture toughness measurement are experimentally complex. However, dynamic fracture toughness determination using strain measurement is extremely attractive in terms of experimental simplicity. In this study, dynamic fracture toughness tests using strain measurement are performed. High rate tension and charpy impact tests are carried out for titanium alloy, maraging steel and Al alloys. In the case of evaluating the dynamic fracture toughness using high rate tension and charpy impact tests, load or energy methods are used commonly. The consideration about inertial effects is essential, because load or energy methods are influenced by inertia. In contrast, if the position for optimum response of strain is provided, dynamic fracture toughness evaluation using strain near crack tip is more accurate. To obtain the position for optimum response of strain, a number of gages were attached at angles of 60°. Reliability for experimental results is evaluated by Weibull analysis. The method presented in this paper is easy to implement in a laboratory and it provides accurate results compared to results from load or energy methods influenced by inertia.

Dynamic Fracture Toughness: Critical Review of Materials and Developments

2013 ◽  
Vol 389 ◽  
pp. 289-297
Author(s):  
Raja Ahsan Javed ◽  
Shi Fan Zhu ◽  
Muhammad Farid
Keyword(s):  
Fracture Toughness ◽  
Dynamic Loading ◽  
Dynamic Fracture ◽  
Critical Review ◽  
Failure Process ◽  
Dynamic Fracture Toughness ◽  
Structure Design ◽  
New Materials ◽  
The Past ◽  
Costly Failure

For design to be more safe, dynamic fracture toughness (DFT) of material needs to be determined. Compared to static loading, dynamic loading procedures are not well established. Calculation of DFT is complicated and costly. Failure process of structures is greatly influenced by dynamic loading. In the past only steel and cast iron were employed for structure design purposes but now many new materials such as (a) composite, (b) alloys (titanium, magnesium), (c) ceramic, (d) concrete, and (e) brittle materials are being used. DFT calculations of materials under dynamic loading have resulted in new theories and experimental techniques. In this paper a critical review of the developments for the calculation of DFT for the materials is presented.

Determination of Dynamic Fracture Toughness at High Loading Rates

2012 ◽  
Author(s):  
Uwe Mayer
Keyword(s):  
Fracture Toughness ◽  
Elastic Waves ◽  
Crack Arrest ◽  
Dynamic Fracture Toughness ◽  
High Loading ◽  
Dynamic Crack ◽  
Testing Time ◽  
Loading Rates ◽  
Propagation Of Elastic Waves

To determine fracture mechanics values at high loading rates from force and displacement signals requires the influences of inertia and the propagation of elastic waves to be taken into account. This paper shows how measurement technique requirements can be fulfilled for determination of key values for a testing time below 100μs for 1T C(T) specimens. Results using this method are given for specimens of 22 NiMoCr 3 7 steel (A 508 C1.2) from a project on correlation between dynamic crack initiation and crack arrest.

Dynamic fracture toughness (JId) behavior of armor-grade Q&T steel weldments: Effect of weld metal composition and microstructure

2009 ◽  
Vol 15 (6) ◽  
pp. 1017-1026 ◽  
Author(s):  
Govindaraj Magudeeswaran ◽  
Visvalingam Balasubramanian ◽  
S. Sathyanarayanan ◽  
Gankidi Madhusudhan Reddy ◽  
A. Moitra ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Weld Metal ◽  
Dynamic Fracture ◽  
Dynamic Fracture Toughness ◽  
Metal Composition ◽  
Weld Metal Composition
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