Standardization of SENT (or SE(T)) Fracture Toughness Measurement: Results of a Round Robin on a Draft Test Procedure

2016 ◽  
Author(s):  
Sanjay Tiku ◽  
Nick Pussegoda ◽  
Morvarid Ghovanlou ◽  
W. R. Tyson ◽  
Aaron Dinovitzer
Keyword(s):  
Fracture Toughness ◽  
Test Procedure ◽  
Potential Drop ◽  
Round Robin ◽  
Single Specimen ◽  
Test Program ◽  
Round Robin Test ◽  
Fracture Toughness Testing ◽  
Growth Measurement ◽  
Toughness Testing

Fracture toughness of steels is conventionally measured using bend specimens and provides a conservative estimate of toughness when the actual loading is in tension. There has been widespread interest in characterizing the toughness that occurs with reduced constraint to better reflect constraint conditions typical of a relatively shallow girth weld flaw. There is currently a standardized approach to measure fracture toughness in tension loaded specimens, however, it requires testing of multiple specimens to generate a resistance curve. Recent developments in fracture toughness testing and analysis of tension loaded specimens have led to publications by CANMET and Exxon Mobil Upstream Research Company toward development of a single-specimen procedure. As part of an initiative to enhance the state of the art in strain based design and assessment methods, with the intent of providing support for the standardization of appropriate weld testing methods, BMT under a Pipeline research Council International (PRCI) project has combined the two single-specimen approaches and developed a recommended practice for fracture toughness testing using single-edge-notched tension SENT (or SE(T)) samples with fixed grip loading. The procedure has been assessed by means of a round robin test program involving laboratories from around the world. Girth welds were fabricated and base metal, heat affected zone and weld center line specimens were prepared and sent to round robin participants. For the round robin program all the participants used a double clip gauge arrangement for direct CTOD measurement and electric potential drop measurement or unloading compliance method for crack growth measurement. In this paper, the results of the round robin test program including comparison of J and CTOD resistance curves will be presented and discussed.

Fracture Toughness Testing of a Low Alloy Structural Steel Using Non-Standard Bend Specimens and an Exploratory Application to Determine the Reference Temperature, T0

2017 ◽  
Author(s):  
Vitor Scarabeli Barbosa ◽  
Claudio Ruggieri
Keyword(s):  
Fracture Toughness ◽  
Structural Steel ◽  
Cleavage Fracture ◽  
Test Procedure ◽  
Reference Temperature ◽  
Width Ratio ◽  
Fracture Toughness Test ◽  
Fracture Toughness Testing ◽  
Loading Mode ◽  
Toughness Testing

This work addresses an experimental investigation on the cleavage fracture behavior of an ASTM A572 high strength, low alloy structural steel using standard and non-standard SE(B) specimens, including a non-standard PCVN configuration. One purpose of this study is to develop a fracture toughness test procedure applicable to bend geometries with varying specimen span over width ratio (a/W) and loaded under 3-point and 4-point flexural configuration. We provide a new set of plastic η-factors applicable to these non-standard bend geometries which serve to estimate the experimentally measured toughness values in terms of load-displacement records. Another purpose is to investigate the effects of geometry and loading mode in fracture tests using non-standard bend specimens. Fracture toughness testing conducted on various bend specimen geometries extracted from an A572 Grade 50 steel plate provides the cleavage fracture resistance data in terms of the J-integral at cleavage instability, Jc. The experimental results show a potential effect of specimen geometry and loading mode on Jc-values which can help mitigating the effects of constraint loss often observed in smaller fracture specimens. An exploratory application to determine the reference temperature, T0, derived from the Master Curve methodology also provides additional support for using non-standard bend specimens in routine fracture applications.

Low-Constraint Toughness Testing: Results of a Round Robin on a Draft SE(T) Test Procedure

2013 ◽  
Author(s):  
William R. Tyson ◽  
James A. Gianetto
Keyword(s):  
Test Procedure ◽  
Round Robin ◽  
Resistance Curve ◽  
Single Specimen ◽  
Single Edge ◽  
Number Of Factors ◽  
The World ◽  
Toughness Testing ◽  
Low Constraint ◽  
Pipe Geometry

Assessment of the effect of girth weld flaws on pipeline integrity requires knowledge of a number of factors: pipe geometry, applied loads, flaw size, and pipe mechanical properties. Of the latter, strength and toughness are the primary factors. Toughness has conventionally been measured using specimens tested in bending to maximize constraint. While this gives a conservative estimate of toughness, it would be better to use a test that would reveal the toughness in constraint conditions typical of girth weld flaws: namely, relatively shallow flaws loaded in tension. Consequently, there is a trend to evaluate toughness using pre-cracked single-edge-cracked tension (i.e. SE(T)) specimens, and one procedure has already been standardized. However, this procedure requires the use of multiple specimens to generate a resistance curve. With the objective of devising a more economical test, a single-specimen procedure has been developed at CANMET. The viability of this procedure has been assessed by means of a round robin involving test and research laboratories from around the world. In this presentation, the results of the round robin will be presented and discussed.

Sign in / Sign up

Export Citation Format

Share Document