Author: Stephen M. Graham Publisher: ISBN: 9781423527633 Category : Languages : en Pages : 92
Book Description
Welds in marine structures are typically fabricated such that the yield strength of the weld metal is higher than the base plate (over-matched). Allowing the weld metal yield strength to be less than the base metal (under- matching) can increase productivity and weld metal toughness; however, there is some concern that under-matching increases the crack driving force and decreases the weld metal tearing resistance. This study examined fracture behavior of two HY-100 under-matched welds under dynamic loading. A new test fixture that provided greater control of specimen deflection during impact testing of SE(B) specimens was developed, as was a procedure for applying the Normalization Method to the analysis of dynamic fracture toughness tests. Successful application of Normalization involved using multiple specimens with varying ductile crack growth to establish the correct form for the plasticity function. The accuracy of the measured J(sub Id) was verified by comparing with multi- specimen J(sub Id) values. The results from these tests showed that the proximity of the crack tip to the fusion line had more effect on fracture behavior than mismatch level. Narrower fusion line margins led to lower tearing resistance and a greater propensity for fracture instability.
Author: SM. Graham Publisher: ISBN: Category : Dynamic fracture toughness Languages : en Pages : 19
Book Description
This study examined fracture behavior of two HY-100 under-matched welds under dynamic loading. A new test fixture that provided greater control of specimen deflection during impact testing of SE(B) specimens was developed, as was a procedure for applying the Normalization Method to the analysis of dynamic fracture toughness tests. Successful application of Normalization involved using multiple specimens with varying ductile crack growth to establish the correct form for the plasticity function. The accuracy of the measured JId was verified by comparing with multi-specimen JId values.
Author: Publisher: ISBN: Category : Languages : en Pages : 42
Book Description
Lower bound dynamic fracture toughness parameters for HY-80 and HY- 130 steel and their weld metals are identified. Specific values of the parameters K sub Id and K sub Im obtained from direct measurements are reported together with estimates inferred from the large body of Charpy energy, nil ductility transition temperature and dynamic tear energy measurements. The emphasis is on reasonable lower bound values at 30 F, the lowest anticipated service temperature, for use in elastodynamic analyses of crack growth initiation, propagation, and arrest in ship structures. For these conditions, it has been found that the ratio K sub Id/RHO sub Y is approximately sq root of 1 in. Consequently, HY-80 plate appears to be substantially more resistant to fracture under dynamic loading than are the other three grades examined.
Author: J. R. Hawthorne Publisher: ISBN: Category : Languages : en Pages : 47
Book Description
New fracture control guidelines for welded ship hulls have been proposed as a result of an investigation sponsored by the Ship Structure Committee of the Maritime Transportation Research Board. These guidelines include fracture toughness requirements in terms of the Drop Weight-NDT temperature Dynamic Tear (DT) energy. To aid the implementation of these criteria an exploratory program was undertaken to characterize the dynamic fracture toughness of ordinary-strength shipbuilding steels, namely, ABS Grades A, B, C, D, E, and CS. Test materials (plate) were obtained at random from several shipyards and steel mills in an effort to characterize the products of current steel making practice. Fracture toughness trends were defined by means of Drop Weight-NDT, 1-in. DT and standard Charpy V-notch tests and the observed toughness characteristics were compared with the proposed toughness criteria. (Modified author abstract).
Author: T. Ochiai Publisher: ISBN: Category : Brittle fracture Languages : en Pages : 34
Book Description
Fracture toughness properties of structural steels of 490-MPa strength class and weld metals under dynamic loading are studied in the light of the near crack tip stress fields. The loading rate in toughness tests range from 0.1 to 500 mm/s. The near-tip stress fields are analyzed by 3D-FEM considering the strain rate effect on the flow properties of materials. Temperature rise caused by high-speed plastic deformation is also included in the FE analysis. The critical CTOD at brittle fracture initiation decreases when increasing the loading rate. This is due to the elevation of a local stress near the crack tip. The local approach is applied to the dynamic fracture toughness evaluation. It is shown that the brittle fracture resistance evaluated in terms of the Weibull stress, an integrated stress over a highly stressed region near the crack tip, is a material property independent of the loading rate. Based on the Weibull stress fracture criterion, the dynamic fracture toughness can be predicted from static toughness results. An engineering procedure to estimate the loading rate effect on the fracture toughness is also presented.
Author: R. W Judy (Jr) Publisher: ISBN: Category : Materials Languages : en Pages : 16
Book Description
Representative samples of 5Ni-Cr-Mo-V steel in the product forms of plate and weld metal were investigated with respect to fracture toughness characterization features provided by the Dynamic Tear and Charpy V-notch tests. The intrinsic fracture propagation features were defined by the energy-temperature relationships obtained with the dynamic tear test. (Author).
Author: William N Sharpe (Jr) Publisher: ISBN: Category : Materials Languages : en Pages : 88
Book Description
Quantification of the dynamic fracture toughness of structural materials is essential to a wide range of problems - from nuclear accidents to ordnance applications. However, the difficulties associated with accurate measurements of cracks under dynamic loading are considerable. Thus there are no standardized procedures and few reliable results. This work describes a systematic study of the dynamic fracture toughness of SAE-01 tool steel, 4340 and HY100 steels and a tungsten, using the ISDG (Interferometric Strain/Displacement Gage) system which has very high frequency resolution. The major advantage of the method is that information is obtained very close to the crack tip, so that stress wave loading effects are accounted for. A detailed error analysis gives an uncertainty of -10% to +20% in the determination of fracture toughness, which compares with + or - 20% for published work.
Author: Stephen M. Graham
Author: SM. Graham
Author: Ravinder Chona
Author: 
Author: Welding Institute
Author: J. R. Hawthorne
Author: T. Ochiai
Author: R. W Judy (Jr)
Author: Ping Yong
Author: William N Sharpe (Jr)