Papers by P. R. Sreenivasan
Fracture properties of different microstructural regions of the heat affected zone (HAZ) of modif... more Fracture properties of different microstructural regions of the heat affected zone (HAZ) of modified 9Cr-1Mo steel (tempered base metal, intercritical, fine grained, coarse grained with and without δ-ferrite) have been studied by Charpy impact test. Simulation technique is used to reproduce HAZ microstructures. The fine-grained region shows highest toughness and the coarse grained with δ-ferrite shows the lowest. The results have been analysed in terms of tensile properties and microstructural features. The inter particle distance seems to affect the energy absorbed up to fracture both in the tensile tests and Charpy impact test. The highest toughness is obtained for an optimum inter-particle spacing.
A correlation of reference temperature, T 0 with T 0Sch dy had been proposed by the authors earli... more A correlation of reference temperature, T 0 with T 0Sch dy had been proposed by the authors earlier, where T 0Sch dy is the reference temperature corresponding to a median K Id = 100 MPa√m evaluated by the ASTM E1921 procedure applied to K Id vs T data, and K Id has been calculated from instrumented CVN impact test data using modified Schindler relations. This paper applies the above method to some new results from the literature. In addition, a new correlation has been obtained that relates the micro-cleavage fracture stress, σ f , to the static Master Curve (MC) and T 0 based on a knowledge of variation of dynamic yield stress,σ yd , with temperature, both of which are obtainable from instrumented CVN impact tests. This new methodology has been applied to four steels and the prediction of T 0 and MC are satisfactory when compared to other correlations. The methods seem to be promising and need validation based on more extensive and complete data set.
International Journal of Fracture - INT J FRACTURE, 2000
In this paper, instrumented impact test results obtained using V-notch and precracked Charpy spec... more In this paper, instrumented impact test results obtained using V-notch and precracked Charpy specimens of AISI 308 weld and AISI 316 stainless steels are analysed for determining the plastic ?-factor for three-point bend specimens used in J-integral evaluation. Tested 316 stainless steel specimens were in various thermal aging/cold-work conditions whereas 308 weld specimens were in the as-welded condition. The results are analysed using the various procedures proposed in the literature and compared with experimental and finite element results reported in the literature. Based on our analysis, two polynomial expressions of a/W for ?pl are presented: one gives a sort of upper-bound in the a/W range 0.05–1.0 while the other gives conservative values (i.e., use of this results in J-R curves and J sufficiently conservative for engineering purposes). Both provide a smooth variation of ?pl over the entire a/W range unlike some of the expressions given in the literature which show a discont...
Materials Characterization, 2002
The toughness of the weld heat-affected zone microstructures of a 9Cr-1Mo steel has been studied ... more The toughness of the weld heat-affected zone microstructures of a 9Cr-1Mo steel has been studied with simulated samples. From the Charpy impact test results, the highest toughness in terms of the highest uppershelf energy and the lowest ductile-to-brittle transition temperature have been observed in the intercritical region. The lowest toughness was observed in the coarse prior-austenitic grained martensite region adjacent to the fusion line. The microstructural effect on the toughness has also been discussed.
Journal of Testing and Evaluation, 2001
An empirical expression for computing the dynamic yield stress, σ yd , from the general yield loa... more An empirical expression for computing the dynamic yield stress, σ yd , from the general yield load, P GY , of dynamic tear (DT) specimens has been derived by comparing the results from instrumented drop-weight/impact tests of DT and Charpy V-notch (CVN) specimens of ...
Journal of Nuclear Materials, 1996
Dynamic fracture toughness and Charpy impact properties of a normalised and tempered AISI 403 mar... more Dynamic fracture toughness and Charpy impact properties of a normalised and tempered AISI 403 martensitic stainless steel obtained from instrumented impact tests are presented. Procedures for estimating dynamic fracture toughness (Kid) from the load-time traces obtained in instrumented tests of unprecracked Charpy V-notch (CVN) specimens are considered. The estimated Kid values show reasonable agreement with those obtained from instrumented drop-weight and precracked Charpy tests. Also, except in the upper transition and uppershelf regions, the ASME KIR curve is generally conservative (i.e. gives lower Kid values) when compared to the above Kid estimates. The conservatism of the ASME KIR at the upper transition and uppershelf temperatures needs verification/validation. The lowest Kid values estimated at the lower shelf temperatures for the above steel, namely, 33-42 MPa~/m are in good agreement with the reported values of 35-50 MPa~/m for the same steel in the literature.
Journal of Nuclear Materials, 1987
78 Journal of Nuclear Materials 150(1987) 78 -84 North-Holland. Amsterdam EVALUATION OF AGEING-IN... more 78 Journal of Nuclear Materials 150(1987) 78 -84 North-Holland. Amsterdam EVALUATION OF AGEING-INDUCED EMBRITTLEMENT IN AN AUSTENITIC STAINLESS STEEL BY INSTRUMENTED IMPACT TESTING KG SAMUEL, PR SREENIVASAN, SK RAY and P. RODRIGUEZ ...
International Journal of Pressure Vessels and Piping, 1996
This paper reports the RT NDT and K Id results obtained from instrumented impact and drop-weight ... more This paper reports the RT NDT and K Id results obtained from instrumented impact and drop-weight tests of 9Cr---1Mo welds. RT NDT results for welds prepared using electrodes of diameter 25, 315 and 4 mm agree within 5K, the respective values being 264, 269 and ...
Engineering Fracture Mechanics, 1992
An empirical expression for obtaining the dynamic yield stress, σ yd , from the general yield loa... more An empirical expression for obtaining the dynamic yield stress, σ yd , from the general yield load, p gy , of a Charpy U-notch specimen has been experimentally derived assuming: (i) σ yd is the same for both Charpy U-and V-notch specimens; and (ii) the functional relations ...
International Journal of Pressure Vessels and Piping, 1993
This paper reports the results of analysis of the load-temperature data obtained from instrumente... more This paper reports the results of analysis of the load-temperature data obtained from instrumented impact tests carried out at various temperatures using half-thick Charpy V-notch specimens of a 3·5% Ni (ASTM A 203D) steel. The material was tested after irradiation and after an ...
Transactions of the Indian Institute of Metals
After examining some recent Charpy energyfracture toughness correlations, a mean-2 procedure (M2P... more After examining some recent Charpy energyfracture toughness correlations, a mean-2 procedure (M2P) has been proposed for estimation of reference temperature, T 0 , from CVN tests alone and has been established through a correlative approach. The T 0 estimate from the M2P is referred as, T Q-M2 , and is obtained as the mean value of two different estimates discussed in the text. Simplicity, consistency and assured conservatism of the T QM2 has been demonstrated by comparison with measured T 0 values for some new steels. For the larger conservative estimate, it is suggested to take the larger of the two and this, in most cases happens to be the simple estimate, T Q41b , and is the same as T 41J (the 41 J Charpy energy temperature). The applicability of the M2P for irradiated steels has been demonstrated. A new two-parameter correlation for estimating fracture toughness from Charpy energy has been derived and this gives encouraging results for the steels discussed in this paper.
Materials Science and Technology
Dynamic deformation characteristics such as dynamic yield stress and dynamic strain hardening exp... more Dynamic deformation characteristics such as dynamic yield stress and dynamic strain hardening exponent along with dynamic elastic±plastic fracture toughness for the different microstructural regions of heat affected zone (HAZ) of a nuclear grade 9Cr±1Mo steel have been ...
Materials Science and Technology
The ductilebrittle transition temperature (DBTT) of grade A48P2 steel is characterised based on ... more The ductilebrittle transition temperature (DBTT) of grade A48P2 steel is characterised based on the American Society of Mechanical Engineers (ASME) fracture toughness KIR curve and dynamic master curve approaches. The indexing parameter for the KIR curve, reference ...
Materials Performance and Characterization
International Journal of Materials Research
Further application of the cleavage fracture stress model for estimating the T 0 of highly embrit... more Further application of the cleavage fracture stress model for estimating the T 0 of highly embrittled ferritic steels The semi-empirical cleavage fracture stress model (CFS), based on the microscopic cleavage fracture stress, r f , for estimating the ASTM E1921 reference temperature (T 0)o f ferritic steels from instrumented impact testing of unpre-cracked Charpy V-notch specimens is further confirmed by test results for additional steels, including steels highly embrittled by thermal aging or irradiation. In addition to the ferrite–pearlite, bainitic or tempered martensitic steels (which was examined earlier), acicular or polygonal ferrite, precipitation-strengthened or additional simulated heat affected zone steels are also evaluated. The upper limit for the applicability of the present CFS model seems to be T 41J *160 to 170 8Co rT 0 or T Qcfs (T 0 estimate from the present CFS model) *100 to 120 8C. This is not a clear-cut boundary, but indicative of an area of caution where generation and evaluation of further data are required. However, the present work demonstrates the applicability of the present CFS model even to substantially embrittled steels. The earlier doubts expressed about T Qcfs becoming unduly non-conservative for highly embrittled steels has not been fully substantiated and partly arises from the necessity of modifications in the T 0 evaluation itself at high degrees of embrittlement suggested in the literature.
European Structural Integrity Society, 2002
The present authors had earlier suggested a new (shift) procedure for obtaining the dynamic J R (... more The present authors had earlier suggested a new (shift) procedure for obtaining the dynamic J R (J fracture resistance) curves of ductile alloys from the load-displacement traces of (unprecracked) Charpy V-notch (CVN) specimens (with CVN energy >30 J) and ...
Metallurgical and Materials Transactions A, 2005
CVN tests, using a modified Schindler procedure to evaluate KJd; the result shows close agreement... more CVN tests, using a modified Schindler procedure to evaluate KJd; the result shows close agreement with that obtained from the PCVN tests. The ASME KIR-curve approach proves to be too conserva-tive compared to the obtained trend of the fracture toughness with temperature. ...
Journal of ASTM International, 2012
Uploads
Papers by P. R. Sreenivasan