scholarly journals WES 2808 for brittle fracture assessment of steel components under seismic conditions Part III: Change in CTOD fracture toughness of structural steels by pre-strain and dynamic loading

2016 ◽  
Vol 2 ◽  
pp. 1601-1609 ◽  
Author(s):  
Satoshi Igi ◽  
Yusuke Shimada ◽  
Masao Kinefuchi ◽  
Fumiyoshi Minami
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Dynamic Loading ◽  
Structural Steels ◽  
Fracture Assessment

Fracture Assessment of Welded Joint With Geometrical Discontinuity Using the Weibull Stress

2006 ◽  
Author(s):  
Satoshi Igi ◽  
Takahiro Kubo ◽  
Masayoshi Kurihara ◽  
Fumiyoshi Minami
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Welded Joint ◽  
Fracture Toughness Test ◽  
Geometrical Condition ◽  
Stress Criterion ◽  
Toughness Test ◽  
Fracture Assessment ◽  
Geometrical Discontinuity ◽  
Weibull Stress

Recently the Weibull stress is used as a fracture driving force parameter in fracture assessment. The Weibull stress is derived from a statistical analysis of local instability of micro cracks leading to brittle fracture initiation. The critical Weibull stress is expected to be a critical parameter independent of the geometrical condition of specimens. Fracture toughness test using 3-point bending and tensile tests of welded joint specimens with geometrical discontinuity were conducted in order to study the applicability of fracture assessment procedure based on Weibull stress criterion. Steel plates prepared for this study had tensile strength of 490 MPa for structural use. Two kinds of welded joint specimens, “one-bead welded joint” and “multi-pass welded joint” were prepared for fracture toughness test by using gas metal are welding. In tensile test specimen, corner flaws were introduced at the geometrical discontinuity part at where stress concentration is existed. Three dimensional elastoplastic finite element analyses were also carried out using the welded joint specimen models in order to calculate the Weibull stress. The critical loads for brittle fracture predicted by the Weibull stress criterion from CTOD test results of one-bead and multi-pass welded joint specimens show fairly good agreement with experimental results of welded joint specimens with geometrical discontinuity.

Notch-Ductility Transition of Structural Steels of Various Yield Strengths

1972 ◽  
Vol 94 (1) ◽  
pp. 299-305 ◽  
Author(s):  
A. K. Shoemaker
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Fracture Behavior ◽  
Shear Fracture ◽  
Dynamic Fracture Toughness ◽  
Structural Steels ◽  
Published Data ◽  
Specimen Thickness ◽  
Plastic Energy ◽  
Lateral Contraction

The notch-ductility transition of six structural steels, A36, ABS-Class C, A302-Grade B, HY-80, A517-Grade F, and HY-130, ranging in yield strength from 36 to 137 ksi, was studied with the use of 5/8 and 1 in. dynamic-tear (DT) test specimens. The results were compared with previously published data for V-notch and fatigue-cracked Charpy tests and dynamic fracture-toughness (KID) tests. Energy, lateral-contraction, and fracture-toughness values were compared. The results of this study showed that the full-shear upper energy shelves in the Charpy V-notch and DT specimens are the products of constant average plastic energy densities for each steel and the plastic volume estimates for the fracture of the different specimens. The transition from ductile to brittle fracture behavior is essentially the same in the fatigue-cracked Charpy and DT specimens since, for each steel, the same lateral contraction was measured in each specimen broken at a given temperature. This lateral contraction increased exponentially with temperature until a full-thickness shear fracture developed. However, the maximum lateral contraction increased with increased test-specimen thickness, suggesting that the Kc values corresponding to full-shear fracture should also increase with thickness. Using the proportionality found between the lateral contraction and the values of KID2/σYDE for the brittle-fracture behavior of these steels, the Kc values are estimated to be as much as 4.5 times greater than the KIc values at the same temperatures. In general, the notch-ductility transition can best be quantitatively characterized by the lateral contraction through KID and Kc values, whereas upper shelf energies are related by constant plastic energy densities and plastic volumes which develop during fracture.

Evaluation of Prestraining and Dynamic Loading Effects on the Fracture Toughness of Structural Steels by the Local Approach

2001 ◽  
Vol 123 (3) ◽  
pp. 362-372 ◽  
Author(s):  
Fumiyoshi Minami ◽  
Kazushige Arimochi
Keyword(s):  
Fracture Toughness ◽  
Dynamic Loading ◽  
Temperature Shift ◽  
Steel Structures ◽  
Structural Steels ◽  
Unstable Fracture ◽  
Virgin Material ◽  
Local Approach ◽  
Loading Effects ◽  
Weibull Stress

On the occasion of recent great earthquakes, great concern is focused on the prevention of unstable fracture of steel structures against the seismic loading. This paper employs the local approach for the evaluation of prestraining and dynamic loading effects, experienced during an earthquake, on the fracture toughness of structural steels. The prestraining and dynamic loading lead to a similar result: increasing the yield stress and tensile strength and decreasing the fracture toughness. It is shown, however, that the combined effects of prestraining and dynamic loading is not equivalent to the sum of each individual effect. The analysis using the local approach demonstrates that the critical Weibull stress at brittle fracture initiation is independent of prestraining and dynamic loading. Based on the Weibull stress fracture criterion, the prestraining and dynamic loading effects on the fracture toughness can be predicted from static toughness results of the virgin material. As an engineering application, a simplified method is proposed for the estimation of fracture toughness under the seismic condition. This method uses a reference temperature concept: the dynamic fracture toughness at the service temperature T with prestrain is displaced by the static toughness of the virgin material at a lower temperature T−ΔTPD, where ΔTPD is a temperature shift of the fracture toughness caused by prestraining and dynamic loading. The temperature shift ΔTPD is provided as a function of the flow stress elevation in the seismic condition.

Heat-Affected Zone Fracture Toughness of 420–500-MPa Yield Strength Steels: Effects of Chemical Composition and Welding Conditions

1993 ◽  
Vol 115 (1) ◽  
pp. 66-75 ◽  
Author(s):  
J. P. Tronskar
Keyword(s):  
Fracture Toughness ◽  
Chemical Composition ◽  
Brittle Fracture ◽  
Yield Strength ◽  
Heat Affected Zone ◽  
Welding Process ◽  
Offshore Structures ◽  
Structural Steels ◽  
Coarse Grained ◽  
Experimental Investigations

During the last five years, high-strength steels with yield strengths in the range 420 to 500 MPa have attracted considerable interest within the offshore industry, primarily due to the potential for weight saving and reduction in volume of weld metal through the use of reduced section thicknesses. With respect to chemical composition these steels are developed following much the same philosophoy as for the modern normalized structural steels. Due to the increased stress level in these higher strength steels, it is anticipated that brittle fracture initiation occurring in the coarse-gained HAZ will be more critical for these steels than for the lower strength normalized grades. The objective of this paper is to present the results from several experimental investigations carried out at VERITEC during the last five years to study the factors affecting the crack tip opening displacement (CTOD) fracture toughness of the heat-affected zone (HAZ) in structural steels in the yield strength range 420–500 MPa. Typical CTOD fracture toughnesses of the HAZ in normalized 350-MPa yield strength steels used in offshore structures are also presented for comparison. The results of the investigations confirm that the same chemical compositional factors which are known to influence the HAZ fracture toughness of normalized steels are also important for the 420–500-MPa yield strength steels. It is demonstrated that the width of the HAZ is important for the initiation of brittle fracture of pop-in and that this width must exceed a certain minimum value for such events to occur. For different welding conditions, i.e., welding currents/travel speeds, the width of the coarse-grained HAZ changes considerably along the periphery of the weld bead. Thus, one may obtain widely differing results depending on the exact fatigue pre-crack placement. In addition to the weld cooling time between 800 and 500° C, Δt8/5 and the retention time above 1000° C during the weld thermal cycle, RT1000, the welding process and consumables also exert a strong influence on the CTOD values of the coarse-grained HAZ.

2 1/4% NICKEL STEEL

Alloy Digest ◽  
1980 ◽  
Vol 29 (11) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Brittle Fracture ◽  
Physical Properties ◽  
Heat Treating ◽  
Pressure Vessels ◽  
Nickel Steel ◽  
Subzero Temperatures ◽  
Steel Mills ◽  
Resistance To Brittle Fracture

Abstract The 21/4% Nickel Steel possesses a combination of moderate strength and superior resistance to brittle fracture at subzero temperatures. It is one of the most economical materials for the construction of equipment to operate at temperatures as low as -90 F. It is intended primarily for welded pressure vessels. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SA-378. Producer or source: Alloy steel mills and foundries.

Effect of desulphurization on the fracture toughness of structural steels at climatic temperatures

1990 ◽  
Vol 22 (11) ◽  
pp. 1569-1577
Author(s):  
A. Yu. Shul'te ◽  
A. V. Prokopenko ◽  
Yu. M. Tomkin ◽  
V. M. Stepkov
Keyword(s):  
Fracture Toughness ◽  
Structural Steels
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