P.K. Singh

Effect of Structural Heterogeneity on In Situ Deformation of Dissimilar Weld Between Ferritic and Austenitic Steel

Abstract Low-alloy steel and 304LN austenitic stainless steel were welded using two types of buttering material, namely 309L stainless steel and IN 182. Weld metals were 308L stainless steel and IN 182, respectively, for two different joints. Cross-sectional microstructure of welded assemblies was investigated. Microhardness profile was determined perpendicular to fusion boundary. In situ tensile test was performed in scanning electron microscope keeping low-alloy steel-buttering material interface at the center of gage length. Adjacent to fusion boundary, low-alloy steel exhibited carbon-depleted region and coarsening of matrix grains. Between coarse grain and base material structure, low-alloy steel contained fine grain ferrite-pearlite aggregate. Adjacent to fusion boundary, buttering material consisted of Type-I and Type-II boundaries. Within buttering material close to fusion boundary, thin cluster of martensite was formed. Fusion boundary between buttering material-weld metal and weld metal-304LN stainless steel revealed unmixed zone. All joints failed within buttering material during in situ tensile testing. The fracture location was different for various joints with respect to fusion boundary, depending on variation in local microstructure. Highest bond strength with adequate ductility was obtained for the joint produced with 309L stainless steel-buttering material. High strength of this weld might be attributed to better extent of solid solution strengthening by alloying elements, diffused from low-alloy steel to buttering material.

Three-Dimensional Thermomechanical Simulation and Experimental Validation on Failure of Dissimilar Material Welds

Dissimilar material weld joints, consisting of low-alloy steel and 304LN austenitic stainless steel (SS), have critical application in boiling water reactors in the nuclear industry. It was predicted that phase transformation adjacent to the fusion boundary and stress distribution across the transition joint play a key role in the structural degeneration of these welds. Quantitatively, to evaluate their contribution, two different joints were considered. One was fabricated with buttering material 309L SS (M/S Mishra Dhatu Nigam Limited, Hyderabad, India), and the other was produced with buttering material IN182 (M/S Mishra Dhatu Nigam Limited, Hyderabad, India). Base materials remained the same for both. Thermomechanical simulation on dissimilar material welds was performed using finite-element modeling to predict the thermal effect and stress prone area. Temperature-dependent thermal and structural properties were considered for simulation. Simulation results were compared with microstructural characteristics, and data were obtained from the in-situ tensile test. Simulation results exhibited that stress was at maximum in the buttering material and made the zone weaker with respect to adjacent areas. During the validation of results, it was observed that failure occurred through buttering material and endorsed the inference. The variation in mechanical properties of the two welds was explained considering the effect of thermal state and stress distribution.

Characterization of GM-CSF-inhibitory factor and Uracil DNA glycosylase encoding genes from camel pseudocowpoxvirus.

The present study describes the PCR amplification of GM-CSF-inhibitory factor (GIF) and Uracil DNA glycosylase (UDG) encoding genes of pseudocowpoxvirus (PCPV) from the Indian Dromedaries (Camelus dromedarius) infected with contagious ecthyma using the primers based on the corresponding gene sequences of human PCPV and reindeer PCPV, respectively. The length of GIF gene of PCPV obtained from camel is 795 bp and due to the addition of one cytosine residue at position 374 and one adenine residue at position 516, the open reading frame (ORF) got altered, resulting in the production of truncated polypeptide. The ORF of UDG encoding gene of camel PCPV is 696 bp encoding a polypeptide of 26.0 kDa. Comparison of amino acid sequence homologies of GIF and UDG of camel PCPV revealed that the camel PCPV is closer to ORFV and PCPV (reference stains of both human and reindeer), respectively.

Water Intensity of Milk Production: A Comparative Analysis from Waterscarce and Water Rich Regions of India

Livestock plays an important role in socio-economic development of the rural population and also contributes significantly to Indias economy. Dairy farming is one of the water intensive livelihood activities in rural area because it consumes lot of embedded water in the form of feed and fodder. The overall objective of the present study was to estimate the irrigation water productivity of milk production in water rich and water scarce regions of India. The study shows that total irrigation water used to produce a litre of milk from buffalo, crossbred cow and indigenous cow is 3.27 m3, 2.18 m3 and 2.30 m3 respectively in Gujarat, whereas, 5.49 m3, 3.01 m3 and 4.86 m3 respectively in Punjab. In case of Kerala, total water used for producing a litre of milk from buffalo, crossbred cow, and indigenous cow is 3.90 m3, 2.51 m3 and 3.45 m3 respectively. India has a vast bovine population dominated by unproductive/low milk yielding animals and these animals are competing with the natural resources i.e. land and water. Further amplification of bovine population in the country would add additional burden on already over-exploited natural resources including water. The gradual replacing a part of water intensive milk producing animal with water efficient milk producing animal, would help not only reduce the population of the unproductive animals but also substantially ease the pressure on our precious irrigation water without compromising on milk production. It is imperative to use available natural grasses which are available in forest/grazing land as a fodder for dairy animals to cut down the irrigation water which is used for fodder production. Further more it is required to cultivate water efficient green fodder crops to cut down the blue water use for milk production.

Erratum to: Intergranular Corrosion Behavior of 304LN Stainless Steel Heat Treated at 623 K (350 °C)

RAGHUVIR SINGH, Principal Scientist, MUKESH KUMAR, Project Staff, MAINAK GHOSH, Senior Scientist, GAUTAM DAS, Sr. Principal Scientist, and I. CHATTORAJ, Chief Scientist, are with the CSIR-National Metallurgical Laboratory, Jamshedpur 831007, India. Contact e-mail: raghujog@yahoo.co.in; rsr@nmlindia.org P. K. SINGH, Scientific Officer G, is with Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai, India. The online version of the original article can be found under doi:10.1007/s11661-012-1519-4. Article published online April 9, 2013

Study on Sensitization Susceptibility and Texture of Cold Rolled AISI 304LN Stainless Steel

Attempt has been made to correlate the cold rolling (CR) texture with the degree of sensitization (DOS) in rolled 304LN after ageing at 500-600oC for various durations. The susceptibility of sensitization is observed to increase with %CR cold rolling from 5-25% and aged at 500-600oC. No one to one correlation between texture and DOS is observed. Brass component, overall, seems better for lower DOS while Goss component led to relatively higher DOS values. It is observed that the ratio of Brass to Copper may have a critical value for lower DOS.