FRACTURE MECHANICS 1

[IMV]

i am looking for articles and papers on CTOA (Crack Tip Opening Angle) and use of Charpy testing on high grade steels used in Pipelines.

would be good if someone can provide it to me.

thanks

 

[kslee1000]

Try post on "Material Engineering Other Topic" may bring you a few responses. Not many people here have that type of training.

 

[rb1957]

a quick yahoo for "charpy testing of high strength steels" found ...
Applied Mechanics and Materials Vols. 3-4 (2005) pp 369-376
online at

http://www.scientific.net

© (2005) Trans Tech Publications, Switzerland
Online available since 2006/Aug/15

Measurement and Analysis of Impact Test Data for X100 Pipeline Steel
1S. H. Hashemi1,a, I. C. Howard2,b , J. R. Yates2,c and R. M. Andrews3,d
1The University of Birjand, Department of Mechanical Engineering, Birjand, Iran
2The University of Sheffield, Department of Mechanical Engineering, Sheffield, UK
3Advantica, Loughborough, UK
ashhashemi@birjand.ac.ir, bi.howard@shef.ac.uk, cj.yates@shef.ac.uk,
dbob.andrews@advantica.biz
Keywords: strain gauge load-cell, instrumented Charpy machine, ductile fracture, pipeline steel.
Abstract. Charpy upper shelf energy is widely used as a fracture controlling parameter to estimate
the crack arrest/propagation performance of gas transportation pipeline steels. The measurement of
this fracture criterion particularly for modern steels and its apportion into different components, i.e.
fracture and non-related fracture energy, are of great importance for pipeline engineers.
This paper presents the results of instrumented Charpy impact experiments on high-grade pipeline
steel of grade X100. First, the instrumentation technique including the design and implementation
of a strain gauge load-cell and the details of the data-recording scheme are reviewed. Next, the
experimental data obtained from the Charpy impact machine so instrumented are presented and
discussed. These include the test data from full and sub-sized Charpy V-notched specimens. The
instrumented Charpy machine was able to capture the load history in full during the fracture process
of the test specimens resulting in a smooth load-time response. This eliminated the need for filtering
used in similar test techniques. From the recorded test data the hammer displacement, impact
velocity and fracture energy were numerically calculated.
The results showed that there was a significant drop in hammer velocity during the impact event.
This resulted in a change in the fracture mode from dynamic to quasi-static which was more
appreciable for full-size Charpy test samples. As a result, sub-sized specimens might be preferable
for impact testing of this steel in order to guarantee the conditions of dynamic crack propagation in
the specimen ligament. Accurate analysis of the instrumented impact test data showed that the ratio
of crack initiation energy to propagation energy was around 30% for the X100 steel. It can be
concluded that in impact testing of high-grade pipeline steel a significant portion of overall fracture
energy is consumed in non-related fracture processes. This high fracture initiation energy should be
accounted for if the current failure models are going to be used for toughness assessment of highstrength
low-alloy gas pipeline steels.
Introduction
Charpy upper shelf energy is widely used to estimate the ductile fracture toughness of gas
transmission pipelines [1-3]. The resistance of the pipeline to ductile propagating fracture is
typically measured in terms of Charpy energy on standard V-notched specimens. These are hit at
their mid-span by a heavy swinging pendulum. The fracture energy absorbed by the specimen is
read from a dial indicator. This energy is correlated then to the pipe ductile tearing resistance
through semi-empirical formulae. These formulae relate the pipe geometry and loading conditions
to its Charpy fracture energy. Such equations are the results of calibration schemes using test data
from laboratory scale impact specimens and failure information from full-scale burst experiments.
Copy,Edit and Printing deactivated. Original document has 8 pages
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http://www.scientific.net/requestpaper/36636

Applied Mechanics and Materials Vols. 3-4 (2005) pp 369-376

would you like us to read it for you too ?

 

[kslee1000]

rb:

I am tuning my receiver in

 

[IMV]

thanks kslee1000's

 

[kslee1000]

You welcome, and good luck. Too bad, I don't see an Engineering Mechanics Forum around.