Influence of Mean Stress on Ductile Fracture Properties

1981 ◽  
pp. 179-188
Author(s):  
T. Suzuki ◽  
S. Yanagimoto
Keyword(s):  
Ductile Fracture ◽  
Mean Stress ◽  
Fracture Properties

Fracture Toughness of Aged Stainless Steel Primary Piping and Reactor Vessel Materials

1987 ◽  
Vol 109 (4) ◽  
pp. 440-448 ◽  
Author(s):  
W. J. Mills
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Ductile Fracture ◽  
Thermal Aging ◽  
Fracture Resistance ◽  
Reactor Vessel ◽  
Initiation Toughness ◽  
Second Phase ◽  
Premature Failure ◽  
Fracture Properties

The ductile fracture toughness behavior of FFTF primary piping and reactor vessel construction materials was characterized using the multiple-specimen JR-curve technique before and after 10,000-hr thermal aging treatments. The test materials included Types 304 and 316 stainless steel (SS) and Types 308 and 16–8–2 SS welds. In the unaged condition, these alloys exhibited very high Jc initiation toughness and tearing modulus values at elevated temperatures (427–538°C). The fracture resistance for the 316 SS piping was found to be dependent on orientation; Jc values for the axial (C–L) direction were 60 to 70 percent lower than those for the circumferential (L–C) orientation. The lower fracture properties in the C–L orientation resulted from premature failure of stringers aligned in the axial direction. Thermal aging at 427° C caused no degradation in fracture resistance, while 482 and 566° C agings resulted in a modest 10 to 20 percent reduction in Jc for both base and weld metals. Residual toughness levels after aging are adequate for precluding any possibility of nonductile fracture. Hence, conventional stress and strain limits, such as those provided by the ASME Code, are sufficient to guard against ductile fracture for SS components that have accumulated 10,000-hr exposures at or below 566° C. Metallographic and fractographic examinations revealed that the degradation in fracture properties was associated with aging-induced second-phase precipitation.

Effect of Microstructure on Formation of Ductile Fracture Surface in Steel Plate

2011 ◽  
Vol 409 ◽  
pp. 678-683
Author(s):  
Tomoaki Fukahori ◽  
Shinichi Suzuki ◽  
Naoya Yamada ◽  
Masatoshi Aramaki ◽  
Osamu Furukimi
Keyword(s):  
Tensile Strength ◽  
Fracture Surface ◽  
Surface Morphology ◽  
Ductile Fracture ◽  
Fracture Property ◽  
Deformation Energy ◽  
Steel Plates ◽  
Void Coalescence ◽  
Fracture Properties ◽  
Fractured Surface

In recent years, high strength steel plates for building and pipelines have been required to improve ductile fracture properties, assuming ground deformation in earthquake-prone region. The ductile fracture is performed by the result from coalescence of micro-voids followed by the nucleation and growth [1]. Fractured surface morphology reflects the void coalescence process, so it is important to consider the relationship between the fracture surface morphology and the micro-voids formation beneath the fractured surface to consider the ductile fracture properties. The voids nucleate sites are mainly particles such as inclusions or precipitates, and grain boundries. These voids grow and coalesce according to three modes. The first mode is directly coalescence of voids followed by growth [2]. The second one is the coalescence of voids caused by shear deformation followed by internal necking between voids [3]. The third one is the coalescence of voids caused by micro-voids nucleation in shear band between two larger voids [4]. It is expected that these modes influence local elongation property which is one of the indices for ductile fracture property through the formation of fractured surface. In this study, local deformation energy which is measured by load-displacement curve in tensile test is examined by focusing the voids nucleation, growth and coalescence, for high tensile strength plates of TS480-830MPa which is controlled by the microstructure through the cooling rate of heat treatment. The deformation energy is useful to consider the ductile fracture property of steel plates which have a different tensile strength.

Calibration of ductile fracture properties of a cast aluminum alloy

2007 ◽  
Vol 459 (1-2) ◽  
pp. 156-166 ◽  
Author(s):  
H. Mae ◽  
X. Teng ◽  
Y. Bai ◽  
T. Wierzbicki
Keyword(s):  
Aluminum Alloy ◽  
Ductile Fracture ◽  
Cast Aluminum Alloy ◽  
Cast Aluminum ◽  
Fracture Properties

Hydrotest Protocol for Applications Involving Lower-Toughness Steels

2004 ◽  
Author(s):  
B. N. Leis ◽  
R. D. Galliher ◽  
R. L. Sutherby ◽  
R. Sahney
Keyword(s):  
Ductile Fracture ◽  
Effective Means ◽  
Hold Time ◽  
Response Characteristic ◽  
Maximum Pressure ◽  
Fracture Properties ◽  
Transmission Pipeline ◽  
Shear Lip ◽  
Resistance Weld ◽  
Time Required

Hydrotesting has been used by the transmission pipeline industry for decades, and remains the only effective means to control stress-corrosion cracking until in-line inspection is proven. This paper addresses the conditions for effective proof-pressure testing in terms of ductile fracture referenced to peak pressure and hold-time, and then contrasts these to the response in low-toughness situations. Fracture properties typical of an early-vintage electrical-resistance weld (ERW) seam were determined and used as the basis to simulate the response at toughness levels typical of some lower-toughness steels. Fracture properties characterized via Charpy-vee notch (CVN) energy showed low energy to failure, and confined inelastic response characteristic of linear-elastic fracture mechanics. Hydrotest and service breaks associated with cracking in an ERW seam showed a very small shear lip and often showed chevrons pointing back toward the origins — features consistent with the CVN results and characteristic of low fracture ductility. The results indicate hydrotest protocols derived and effective for ductile fracture are not directly applicable when brittle-like fracture controls. Hydrotesting was indicated to be an effective means to expose defects in ERW seams, as rupture is indicated to occur under typical hydrotest conditions. Simulated growth of the scope of defect lengths and depths evident along hydrotest breaks showed virtually no time dependent cracking, which means the hold time at maximum pressure should be reduced to the minimum time required to ensure all pipe in the test section has reached its target pressure.

scholarly journals Effects of Mold Media and Porosity on Ductile Fracture Properties of Cast Aluminum Alloy A356

2008 ◽  
Vol 57 (9) ◽  
pp. 913-920 ◽  
Author(s):  
Hiroyuki MAE ◽  
Xiaoqing TENG ◽  
Yuanli BAI ◽  
Tomasz WIERZBICKI
Keyword(s):  
Aluminum Alloy ◽  
Ductile Fracture ◽  
Cast Aluminum Alloy ◽  
Cast Aluminum ◽  
Fracture Properties
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