Effect of Fracture Speed on Ductile Fracture Resistance: Part 2—Results and Application

2010 ◽  
Author(s):  
Da-Ming Duan ◽  
Joe Zhou ◽  
Do-Jun Shim ◽  
Gery Wilkowski
Keyword(s):  
Fracture Toughness ◽  
Steady State ◽  
Ductile Fracture ◽  
High Speed ◽  
Material Selection ◽  
Basic Material ◽  
Pipe Material ◽  
High Grade ◽  
Control Plan ◽  
Material Fracture

One of the many aspects of natural gas pipeline design and material selection is the consideration of propagation and arrest of high-speed axial ductile fracture in the line pipes. Understanding the material ductile fracture behavior is essential for establishing an integrated fracture control plan. This is particularly important for pipelines of high design pressures utilizing large-diameter and high-grade line pipes. The procedure of Battelle Two-Curve Method (TCM) has been most commonly used in ductile fracture analysis in the prediction of fracture speed and minimum arrest toughness for axially running cracks. In the past decades, discussions and research have been in that the TCM approach, among with others, could not accurately predict either fracture speed or minimum arrest fracture toughness for high-grade pipes, and with pipe grade increasing the prediction errors are getting larger. Recent research work at TransCanada indicates that for a better prediction of pipeline ductile fracture, understanding the basic material mechanical behavior and its fundamental fracture mechanism is essential. One of the important findings of the work is that pipe material fracture toughness is not a constant as being commonly treated, rather the fracture toughness, in terms of both steady-state CTOA and steady-state DWTT fracture energy is fracture speed dependent, being decreasing with increasing fracture speed. Corresponding modifications have been made to the traditional TCM by introducing speed-dependent fracture toughness. The improved model gives much better predictions in both fracture speed and toughness for high grade pipes. This paper presents recent work at TransCanada, together with its industry partner Engineering Mechanics Corporation of Columbus (EMCC), on high-speed pipe-material fracture testing technique (using the modified back-slot DWTT specimen) and high-grade material testing data. The test data supports the predictions of early published work on speed-dependent fracture toughness. The fracture speeds obtained from the modified back-slot DWTT specimens were very close to actual full-scale pipeline ductile fracture speeds and this in turn enhanced the applicability of the modified TCM model.

An Updated Fracture Resistance Dataset of Pipeline Ductile Fracture Propagation Based on High Speed DWTT Tests

2014 ◽  
Author(s):  
Da-Ming Duan ◽  
James Ferguson ◽  
Joe Zhou ◽  
Mohammed Uddin ◽  
Do-Jun Shim
Keyword(s):  
Fracture Toughness ◽  
Steady State ◽  
Ductile Fracture ◽  
High Speed ◽  
Fracture Propagation ◽  
Gas Pipeline ◽  
Charpy Specimen ◽  
Low Grade ◽  
Speed Dependence ◽  
Fracture Control

One of the major research topics in the area of gas pipeline fracture control is the suitability of using Charpy energy for ductile fracture control for modern and/or high strength line pipes. A common understanding is that, for pipe body crack self-arresting, the deviation of the actual required Charpy energy from those predicted using the traditional procedure of Battelle Two-Curve Method (TCM) is getting larger with higher strength pipes. DWTT is being paid more attention to because of its larger and full thickness specimen that can better capture the fracture process than a Charpy specimen does. Previous work at TransCanada indicated that various fracture speeds can be achieved in DWTT specimens and it is the steady-state fracture speed that is representative to the actual fracture propagation in a gas pipeline. It has also been found that the steady-state fracture toughness, in terms of either fracture energy or CTOA, is fracture speed dependent with lower fracture toughness for higher fracture speeds. Previous analysis also indicated by considering the speed dependent toughness, better predictions can be obtained for both self-arresting fracture toughness requirement and the fracture propagation speed. Previous DWTT fracture toughness data published by the authors exhibited a strong speed dependence and it was demonstrated that if the actual speed dependence is plugged into the modified TCM, both the fracture toughness and fracture speed would be over predicted. The assumption was that the original TCM was calibrated using pipe fracture data that also had speed dependent fracture toughness but the speed dependence was less strong than those for the modern pipes. This paper presents an updated DWTT fracture dataset that expands the previously published data by adding high speed DWTT test results of modern line pipe steels with a range of grades X70-X100 and three old vintage pipe materials that is representative to the pipes that were used for the original TCM testing and calibration. The toughness data for the low grade pipes also shows speed dependence which purports the previous assumption.

Ductile Fracture Resistance Measurements in High Grade Steels

2006 ◽  
Author(s):  
L. N. Pussegoda ◽  
A. Fredj ◽  
A. Fonzo ◽  
G. Demofonti ◽  
G. Mannucci ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Steady State ◽  
Ductile Fracture ◽  
Fracture Resistance ◽  
Process Zone ◽  
Fracture Propagation ◽  
Crack Tip ◽  
Opening Angle ◽  
Displacement Curve ◽  
High Grade

Recent developments in ductile fracture resistance measures in high grade steels in the pipeline industry include the crack tip opening angle (CTOA) and “steady state” fracture propagation energy, using 3-point bend specimens. The CTOA has been found to be a function of specimen ligament size. With the availability of instrumented hammers, it became possible to resolve propagation energy using the load-displacement curve using a single specimen. This paper focuses on refining the steady state fracture propagation energy, using back-slotted Drop Weight Tear Test (DWTT) specimens. The study included numerical simulation of the dynamic response of back-slotted specimens. The significance of the back-slot in altering the stress/strain field ahead of the propagation crack is discussed. The numerical simulation was also used to determine the strain rate in the “process zone” of the crack tip during steady state fracture propagation.

Ductile Fracture Resistance Modeling Approach in Two High Grade Steels

2006 ◽  
Author(s):  
L. N. Pussegoda ◽  
A. Fredj ◽  
A. Dinovitzer ◽  
D. Horsley ◽  
D. Carlson
Keyword(s):  
Steady State ◽  
Crack Propagation ◽  
Ductile Fracture ◽  
Fracture Resistance ◽  
Fracture Propagation ◽  
Tension Test ◽  
Model Parameters ◽  
High Grade ◽  
Damage Mechanisms ◽  
Point Bend

Recent developments in ductile fracture resistance measures in high grade steels in the pipeline industry include the crack tip opening angle (CTOA) and “steady state” fracture propagation energy, using 3-point bend specimens. The CTOA has been found to be a function of specimen ligament size. Alternatives would be “steady state” fracture propagation energy, critical fracture strain and adoption of damage mechanisms. This paper focuses on modeling approaches for crack propagation using damage mechanisms. The tension test is used to “calibrate” the damage model parameters and applied to the crack propagation in a 3-point bend specimen in candidate high grade steels. The effects of using parameters developed from tension test and extending to a 3-point bend crack propagation scenario is discussed.

BELMALLOY

Alloy Digest ◽  
1954 ◽  
Vol 3 (2) ◽  
Keyword(s):  
Fracture Toughness ◽  
Shear Strength ◽  
Physical Properties ◽  
Tensile Properties ◽  
Heat Treating ◽  
High Grade ◽  
Malleable Iron ◽  
Shock Resistance ◽  
High Torque

Abstract BELMALLOY is a high grade pearlitic malleable iron providing rigidity and shock resistance to high torque loads. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength as well as fracture toughness. It also includes information on heat treating, machining, and joining. Filing Code: CI-6. Producer or source: Belle City Malleable Iron Company.

COPPER ALLOY No. C94300

Alloy Digest ◽  
1984 ◽  
Vol 33 (1) ◽  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Corrosion Resistance ◽  
Copper Alloy ◽  
High Speed ◽  
Heat Treating ◽  
Lead Alloy ◽  
Good Resistance ◽  
Tin Bronze ◽  
Strength Medium

Abstract Copper Alloy No. C94300 is a cast copper-tin-lead alloy (bronze). It is characterized by low hardness and strength, medium ductility, excellent machinability and good resistance to corrosion. Commercial names formerly used (but not recommended) are (1) Ingot No. 322, (2) Soft Bronze, (3) High-Leaded Tin Bronze and (4) 70-5-25. This alloy is recommended highly for high-speed bearings at light loads. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive strength as well as fracture toughness. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Cu-470. Producer or source: Copper alloy foundries.

CYCLOPS BHT

Alloy Digest ◽  
1965 ◽  
Vol 14 (2) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Elevated Temperature ◽  
High Speed ◽  
High Speed Steel ◽  
High Strength ◽  
Heat Treating ◽  
High Load ◽  
Structural Components ◽  
Temperature Performance

Abstract Cyclops BHT is a low-alloy martensitic high-speed steel of the molybdenum type recommended for high strength, high load structural components designed for elevated temperature service. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SA-173. Producer or source: Cyclops Corporation.

ELECTRITE COBALT

Alloy Digest ◽  
1960 ◽  
Vol 9 (2) ◽  
Keyword(s):  
Fracture Toughness ◽  
Physical Properties ◽  
High Speed ◽  
Cutting Tools ◽  
High Speed Steel ◽  
Heat Treating ◽  
Heavy Duty ◽  
Steel Company

Abstract ELECTRITE COBALT is a 5% cobalt type high-speed steel recommended for heavy duty cutting tools. This datasheet provides information on composition, physical properties, hardness, and elasticity as well as fracture toughness. It also includes information on forming, heat treating, and machining. Filing Code: TS-89. Producer or source: Latrobe Steel Company.

MOTUNG 652

Alloy Digest ◽  
1957 ◽  
Vol 6 (8) ◽  
Keyword(s):  
Fracture Toughness ◽  
Physical Properties ◽  
Tensile Properties ◽  
Sulfur Content ◽  
High Speed ◽  
High Speed Steel ◽  
Heat Treating ◽  
Bend Strength ◽  
Machining Properties

Abstract MOTUNG 652 is an intermediate molybdenum-tungsten type of high-speed steel conforming to the M-2 analysis. It is available with normal sulfur content or with high sulfur for free machining properties. This datasheet provides information on composition, physical properties, hardness, tensile properties, and compressive and bend strength as well as fracture toughness. It also includes information on forming, heat treating, and machining. Filing Code: TS-61. Producer or source: Cyclops Corporation.

EXOCUT

Alloy Digest ◽  
1973 ◽  
Vol 22 (11) ◽  
Keyword(s):  
Fracture Toughness ◽  
Surface Treatment ◽  
Tool Steel ◽  
High Speed ◽  
Heat Treating ◽  
Heat Treated

Abstract EXOCUT is a super high-speed tool steel capable of being heat treated to Rockwell C 70. It is well suited for machining hard and difficult-to-machine materials. This datasheet provides information on composition, hardness, and elasticity as well as fracture toughness. It also includes information on forming, heat treating, machining, and surface treatment. Filing Code: TS-265. Producer or source: Allegheny Ludlum Corporation.

AISI TYPE M2

Alloy Digest ◽  
1972 ◽  
Vol 21 (2) ◽  
Keyword(s):  
Fracture Toughness ◽  
Wear Resistance ◽  
Compressive Strength ◽  
Physical Properties ◽  
High Speed ◽  
High Speed Steel ◽  
Heat Treating ◽  
General Purpose ◽  
Steel Mills ◽  
Aisi Type

Abstract AISI TYPE M2 is a molybdenum-tungsten high-speed steel with a balanced analysis which produces properties applicable to all general-purpose high-speed uses. It has an excellent balance between toughness and wear resistance. This datasheet provides information on composition, physical properties, hardness, and compressive strength as well as fracture toughness. It also includes information on forming, heat treating, machining, and joining. Filing Code: TS-240. Producer or source: Tool steel mills.

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