Influence of Prior Deformation on Creep Crack Growth Behaviour of 316H Austenitic Steels

2012 ◽  
Author(s):  
Hamed Yazdani Nezhad ◽  
Noel P. O’Dowd ◽  
Catrin M. Davies ◽  
Ali N. Mehmanparast ◽  
Kamran M. Nikbin
Keyword(s):  
Crack Growth ◽  
Creep Crack Growth ◽  
Compact Tension ◽  
Fe Analysis ◽  
Austenitic Steels ◽  
Creep Data ◽  
Growth Behaviour ◽  
Crack Growth Behaviour ◽  
Creep Crack ◽  
Good Agreement

The influence of pre-strain and pre-stress on creep crack growth behaviour of 316H austenitic steels is studied experimentally and numerically in this paper. Compact tension, C(T), specimens (25mm thickness) have been extracted from two steam headers, one as-received and one uniformly compressed to the strain value of 8%. The C(T) specimen extracted from the as-received header was compressed, introducing a non-uniform strain field. Creep crack growth (CCG) tests were performed at 550°C. Comparisons have been provided with the results from as-received C(T) specimens. Finite element (FE) analysis has been carried out to simulate the CCG behaviour of the C(T) specimens. By choosing the problem parameters appropriately, good agreement may be achieved between the FE predictions and the creep data.

Compressive Pre-Strain Effects on the Creep and Crack Growth Behaviour of 316H Stainless Steel

2010 ◽  
Author(s):  
C. M. Davies ◽  
David W. Dean ◽  
A. N. Mehmanparast ◽  
K. M. Nikbin
Keyword(s):  
Stainless Steel ◽  
Crack Growth ◽  
Creep Crack Growth ◽  
Compact Tension ◽  
Growth Behaviour ◽  
Creep Ductility ◽  
Data Set ◽  
Crack Growth Behaviour ◽  
Constraint Effects

The effects of compressive plastic pre-strain on the creep deformation and crack growth behaviour of Type 316H stainless steel have been examined. Creep crack growth (CCG) tests have been performed on compact tension specimens of material which had been uniformly pre-strained by 4% and 8% in compression at room temperature. The CCG behaviour of the pre-compressed material has been interpreted in terms of the creep fracture mechanics parameter C* and compared with that of a significant data set of as-received (un-compressed) specimens and with CCG models. All creep testing has been performed at a temperature of 550 °C. High CCG rates, for a given value of C* have been observed for the pre-compressed material, compared with those of as-received material and these data follow the same trends as the long-term CCG data for as-received material. These observations are explained in terms of specimen constraint effects and variations in creep ductility.

The Influence of Specimen Geometry and Test Times on High Temperature Crack Growth Behaviour in Parent and Welded 316H Stainless Steel

2008 ◽  
Author(s):  
Catrin M. Davies ◽  
Robert C. Wimpory ◽  
Masaakai Tabuchi ◽  
David W. Dean ◽  
Kamran M. Nikbin
Keyword(s):  
Crack Growth ◽  
Large Fraction ◽  
Creep Crack Growth ◽  
Compact Tension ◽  
Parent Material ◽  
Test Duration ◽  
Crack Growth Behaviour ◽  
Creep Crack ◽  
Order Of Magnitude ◽  
Fracture Specimens

Experimental crack growth testing has been performed at 550 °C on a range of fracture specimens including sections taken from a 316 steel weldment. These specimens include the compact tension, C(T), and circumferentially cracked notched bar, CCB, geometries of various sizes. Results are presented from two creep crack growth (CCG) tests on a large and a small CCB weldment specimen. The creep crack initiation (CCI) and growth (CCG) behavior of the CCB weldments has been compared to that of homogeneous parent material (PM) CCB and C(T) specimens and to C(T) weldment specimen data. The data has been analyzed in terms of the C* parameter. The initiation period is found to occupy a large fraction of the test duration for weldments. The CCG rates in the larger CCB weldment test is on the order of six times faster, for a given value of C*, compared to the smaller specimen, indicating a specimen size effect. The CCI times are around an order of magnitude greater for the CCB weldment specimens compared to C(T) weldment data and are higher than that of the PM CCB data. It is recommended that further testing on weldment specimens is performed to affirm the apparent trends.

Sign in / Sign up

Export Citation Format

Share Document