Charpy V-notch energy

The Charpy V-notch energy needed to produce fracture arrest.121... 

Research by Battelle also shows that the Charpy V-notch energy required to prevent ductile fracture propagation can be calculated by the following equation ... 

The Charpy V-notch energy needed to arrest ductile fracture as a function of stress level for API X6G and X70 material in a 30, 36, and 42 in. (760, 915, and 1,065 mm) diameter pipe calculated from this equation is shown graphically in Figure 5.21 (A = 0.1237). The limitation of the Charpy V-notch test is that it is not a full thickness test, whereas the DWTT is. This means in thicknesses more than in., compensation in the form of increased energy absorption requirements is often specified for thick pipe. 

Cy = Charpy V-notch energy K/c = critical stress intensity factor R.A. = reduction in area... 

API Appendix SR 8 covers Charpy V-notch testing on pipe with diameters of 16 in. (405 mm) or greater. The minimum energy acceptance level is specified by the purchaser and... 

Charpy V-notch plateau energy for full size specimen, ft-lbs... 

Select low-temperature steels for fracture-critical structural members designed for tensile stress levels greater than a ksl (40 MPa) and specify a minimum Charpy V notch Impact energy absorption of 20 ft-lb (27 J) for base metal, heat-affected zones (HAZs), and welds when the structures are exposed to low-ambient temperatures. Fracture-critical members are those tension members whose failure would have a significant economic impact. 

For some components, toughness as well as abrasion resistance is required. For example, ditch teeth should have a minimum Charpy V-notch Impact energy of 20 ft-lb (27J) at the design temperature and a minimum hardness of Rockwell C 50-... 

Some specifications require a minimum Charpy v notch impact requirement of 15 ft lb energy absorbed at the minimum expected service temperature. However, this does not mean that a test specimen exhibiting 60 ft lb is four times tougher than the minimum. The main value of notched bar impact testing is as a criterion for acceptance of materials where reliable correlation with service behavior has been obtained. 

Various pressure vessels having shell thicknesses of 3 to 6 inches have failed in a blue-brittle manner at temperatures where the material exhibited 50 or more ft.-lb. Charpy V-notch impact energy. 

Fig. 2. Fe-12Mn. The increase of ductile-brittle transition temperature by martensite embrittling treatment (350 C/2 hr/WQ). CVN Charpy V-notch impact energy (1 ft-lb = 0.735 J).

A = area under the load-clip gauge deflection curve b = uncracked ligament B = specimen thickness Cy = Charpy V-notch E = Young s modulus J = C energy... 

Notch Impact toughness Energy Lateral expansion % shear fracture Dynamic T41J/ Vk, Tq3j, use To,89 mm 7 50% Blunt Charpy V-notch (CVN) impact test e.g., ASTM E 23, EN ISO 148. Obtain curve fit to data vs test temperature, determine various transition temperature indices, e.g., T41J, and upper shelf energy (USE). Initiation and propagation test ... 

In accordance with 10 CFR 50 Appendix G, Paragraph IV A, the reactor vessel beltline materials have minimum upper-shelf energy, as determined from Charpy V-notch tests on unirradiated specimens in accordance with Paragraphs NB-2322.2(a) of the ASME Code, of 75 ft-lbs. Charpy impact tests will be performed on... 

The Charpy V-notch (Cv) upper shelf energy level, in the "weak" (Wr) direction, as obtained per ASTM-A-370 will be no less than 50 ft-lb. A minimum of three Cv specimens will be tested from each plate or forging. 

A 808 High-strenglli low-aUoy steel witJi improved notch toughness V,Nb Hot-rolled plate < 65 mm in thickness Charpy V-notch impact energies of 40-60J (40-60ft Ifb) at-45 C Railway tank cars... 

Test Tensile yield strength atRT Charpy V-notch impact toughness at- 2 C(-80 F) Drop weight tear energy atO C(32 F) ... 

Vacuum induction melted alloy hot worked and annealed for 1 h at 950 C and air cooled. Standard Charpy V-notch impact specimens were machined. The influence of temperature on fracture toughness of 44Ti-49Ni-5Cu-2Fe (wt%). Note that the minimum in the fracture energy occurs just below M, as determined from the corresponding 0.2% yield strength and ultimate tensiie strength measurements. 

Figu re 8.13 Temperature dependence of the Charpy V-notch impact energy (curve A) and percent shear fracture (curve B) for an A283 steel. 

As a typical example, fig. 8 illustrates the effect of rare earth addition on toughness the impact curves are plotted for both longitudinal and transverse Charpy V-notch specimens (Luyckx et al. 1970). In longitudinal specimens, the impact energy at 100% shear, commonly called the shelf energy, is in excess of 5.5 kg m (40 ft lb) in transverse specimens, it is 2kgm (15 ft lb), which is doubled to 4kgm at the Ce/S ratio of 1.5-2.0. 

On the other hand, it is reported that high transverse impact values can be achieved when the R/S ratio is greater than 4 (Waudby 1978). Ackert and Crozier (1973) have shown that the improvement in the Charpy V-notch shelf energy at -18"C occurs at an R/S ratio of 5 to 6 which is much higher than those described above. Ballance and Mintus (1972) have also shown that a marked improvement in the bend performance of steels is obtained at R/S ratios higher than 4. The difference in R/S ratios reported by various... 

Anisotropy of these materials may also be shown by V-notch Charpy impact tests. Since size effects are known to be critical in this type test, standard size specimens were used, thereby eliminating the thin core tank plat( . Charpy V impact energy curves obtained with specimens and notches cut from various orientations from commercial plate and from a plate fabricated l)y the developed procedure are showm in Fig. 5-24 [133]. Differences in both the energy values and transition temperatures are apparent for the arious orientations. These differences are reduced by the developed fabrication procedure. 

Table 5-19 lists selected data on the effects of irradiation on the notch-impact properties of a number of steels. The increase in transition temperature and the percentage of loss of energy absorption are shown as a function of neutron dose. The data were obtained on subsize Izod impact specimens. Limited information on full size Charpy V-notch specimens has indicated that at doses of the order of 5 X 10 fast neutrons/cm, larger transition temperature shifts (by about a factor or two) are observed than with subsize Izod specimens. Thus there may be a size effect to be considered. 

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