Investigation of dynamic strain aging in SA106 Gr.C piping steel

Tensile and J-R tests were carried out under various temperatures and strain rates to understand the characteristics of dynamic strain aging (DSA) in SA106 Gr.C piping steel and to estimate the effect of DSA on the material properties for leak-before-break (LBB) analysis. The manifestations of DSA were clearly observed in the tensile properties. However, the magnitude of serration and strength increase by DSA was relatively small compared to similar grade carbon steels. This may be due to high manganese content in the material. The variation in strain rate did not have a significant effect on the σys at the nuclear reactor operating temperature which falls in DSA region. Ramberg-Osgood parameter n decreased in the region of DSA, and increased with increasing strain rate near the plant operating temperature. The influence of DSA manifested in Ramberg-Osgood parameter α was similar to that in σys. But, it was less clear than that on σys and parameter n. Crack initiation resistance, Ji, and crack growth resistance, dJda, in DSA region were about 30–40% lower than those at RT, and showed the negative loading rate dependence.

[1]  B Mukherjee.  Observations on the effect of post-weld heat treatment on J-resistance curves of sa-106b seamless piping welds , 1989 .

[2]  A. Cottrell,et al.  LXXXVI. A note on the Portevin-Le Chatelier effect , 1953 .

[3]  S. S. Kang,et al.  Dynamic strain aging in SA508-class 3 pressure vessel steel , 1995 .

[4]  B. J. Brindley,et al.  The effect of dynamic strain-ageing on the ductile fracture process in mild steel , 1970 .

[5]  Wa Van Der Sluys,et al.  Effects of Strain Aging in the Unloading Compliance J Test , 1985 .

[6]  C. C. Li,et al.  Effects of dynamic strain aging on the subsequent mechanical properties of carbon steels , 1978 .

[7]  Gery Wilkowski,et al.  Effect of dynamic strain aging on the strength and toughness of nuclear ferritic piping at LWR temperatures , 1994 .

[8]  M. L. Vanderglas.  Experiences using three-dimensional finite element analysis for leak-before-break assessment , 1990 .

[9]  J. D. Baird.  The effects of strain-ageing due to interstitial solutes on the mechanical properties of metals , 1971 .

[10]  Pc McKeighan,et al.  Determining the Potential Drop Calibration of a Fatigue Crack Growth Specimen Subject to Limited Experimental Observations , 1994 .

[11]  K. R. Narendrnath,et al.  A personal computer based system to evaluate J-integral by a single specimen unloading compliance method—part II: Results on A533B class I steel and corona-5 , 1988 .

[12]  Winfried Dahl,et al.  Investigations on strength and ductility of base metals and welded joints of steels for power plants at elevated temperatures , 1992 .

[13]  W. Ramberg,et al.  Description of Stress-Strain Curves by Three Parameters , 1943 .

[14]  B. Russell,et al.  Repeated yielding in tin bronze alloys , 1963 .

[15]  O. E. Lepik,et al.  Ductile fracture properties for assessing leak-before-break issues in ferritic weldments , 1990 .

[16]  B. F. Beaudoin,et al.  Leak-before-break application in US light water reactor balance-of-plant piping , 1990 .

[17]  Derek O. Northwood,et al.  Effect of strain aging on the strength coefficient and strain-hardening exponent of construction-grade steels , 1994 .

[18]  Ss Kang Sung Sik Kang,et al.  Dynamic Strain-Aging Effect on Fracture Toughness of Vessel Steels , 1992 .

[19]  J. K. Chakravartty,et al.  Dynamic strain-ageing of A203D nuclear structural steel , 1983 .