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T R G Kutty - One of the best experts on this subject based on the ideXlab platform.

  • Hot Hardness behaviour of ultrafine grained ferritic oxide dispersion strengthened alloys prepared by mechanical alloying and spark plasma sintering
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2012
    Co-Authors: Karthikeyan Rajan, T R G Kutty, Subramanya V Sarma, B S Murty
    Abstract:

    Abstract The microstructure, Hot Hardness, and indentation creep of ultrafine grained (ufg) 9Cr–1Mo and 9Cr–1W based ferritic oxide dispersion strengthened (ODS) alloys prepared by mechanical alloying and spark plasma sintering are investigated. Studies on Hot Hardness revealed that the Hardness of Mo-containing alloys is higher than that of W-containing alloys. This is attributed to the complete dissolution of Mo while W did not dissolve completely during mechanical alloying. Hardness of Ti containing alloys is higher compared to the base and Y 2 O 3 containing alloys and this is attributed to the presence of Ti–Y–O based nanoprecipitates. Study of Hot Hardness behaviour of ufg ferritic ODS alloys revealed a sharp transition at around 700–800 K. This is possibly due to the enhanced grain boundary mediated plasticity and pronounced reduction in Hall–Petch coefficient with increase in temperature.

  • Effect of temperature on Hardness of binary U–15%Pu alloy and T91 cladding
    Journal of Nuclear Materials, 2012
    Co-Authors: T R G Kutty, K Ravi, Santu Kaity, S.k. Swarnkar, Arun Kumar
    Abstract:

    Abstract The high temperature Hardness behaviour of U–15%Pu and T91 cladding was studied with the help of a Hot Hardness tester. The Hardness versus temperature plot for the T91 alloy consists of two straight lines with different slopes intersecting at 778 K. The Hot Hardness data of orthorhombic α phase of U–15%Pu showed a transition at around 408 K. The appearance of the tetragonal β-phase showed a sudden increase in the Hardness above 828 K. γ-Phase of U–15%Pu was found to very soft. Since U–15%Pu fuel is softer than the T91 cladding above 473 K, the probability of the clad damage by the fuel due to its interaction with the cladding is very less.

  • Hot Hardness and indentation creep study on al 5 mg alloy matrix b4c particle reinforced composites
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006
    Co-Authors: Kirity Bhusan Khan, T R G Kutty, M K Surappa
    Abstract:

    Abstract Al–5% Mg matrix composites reinforced with 10 and 20% B 4 C were prepared by stir casting method. MicroHardness of unreinforced alloy and composites were measured using a Nikon Hot Hardness tester. It was observed that Hardness values decrease gradually with increase in temperature. Transition temperature increases marginally from 262 to 274 °C due to addition of 20% B 4 C. Stress exponent for all the materials varies from 4.3 to 4.5 at temperatures in the range 310 and 370 °C. Apparent activation energy for creep increases with increase in B 4 C content. At temperatures below transition temperature, deformation is attributed to the increased interatomic spacing due to increase in temperature and the unpinning of attractive junction between glide and forest dislocations. At temperatures above the transition temperature, deformation is diffusion assisted phenomenon such as dislocation glide and dislocation climb.

  • Hot Hardness and indentation creep study on Al–5% Mg alloy matrix–B4C particle reinforced composites
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006
    Co-Authors: Kirity Bhusan Khan, T R G Kutty, M K Surappa
    Abstract:

    Abstract Al–5% Mg matrix composites reinforced with 10 and 20% B 4 C were prepared by stir casting method. MicroHardness of unreinforced alloy and composites were measured using a Nikon Hot Hardness tester. It was observed that Hardness values decrease gradually with increase in temperature. Transition temperature increases marginally from 262 to 274 °C due to addition of 20% B 4 C. Stress exponent for all the materials varies from 4.3 to 4.5 at temperatures in the range 310 and 370 °C. Apparent activation energy for creep increases with increase in B 4 C content. At temperatures below transition temperature, deformation is attributed to the increased interatomic spacing due to increase in temperature and the unpinning of attractive junction between glide and forest dislocations. At temperatures above the transition temperature, deformation is diffusion assisted phenomenon such as dislocation glide and dislocation climb.

  • Hot Hardness and indentation creep studies of a Fe–28Al–3Cr–0.2C alloy
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2000
    Co-Authors: Garima Sharma, T R G Kutty, Raju V. Ramanujan, G.p Tiwari
    Abstract:

    The Hot Hardness behaviour of a Fe‐28Al‐3Cr‐0.2C (at.%) alloy was evaluated from room temperature to 1273 K. Indentation creep measurements were also carried out in the temperature range of 843‐963 K. The Hardness‐temperature plot of this alloy showed five distinct regions. The mechanism of deformation operating in each of these regions has been suggested. Indentation creep measurements showed that the stress exponent (n) obtained from the Hardness‐time plots was weakly temperature dependent. The activation energy for high temperature creep was found to be in good agreement with that for self-diffusion of pure iron and in excellent agreement with previous studies. These values of n and activation energy were found to be consistent with dislocation climb as the rate controlling creep mechanism. © 2000 Elsevier Science S.A. All rights reserved.

M. Varga - One of the best experts on this subject based on the ideXlab platform.

  • High temperature abrasion resistance of differently welded structural steels
    Tribology International, 2017
    Co-Authors: H. Rojacz, H. Pahr, S Baumgartner, M. Varga
    Abstract:

    Abstract Structural steels provide a broad spectrum of heat, creep and wear resistance at different microstructures and Hardness levels. Two different steel grades were chosen for investigation and simulated repair welds with different parameters were performed, aiming on the influence of heat input during welding and the resulting microstructure on the high temperature abrasion resistance. The impact on the wear resistance and its temperature dependence was evaluated within a high temperature three-body abrasion test and a Hot Hardness test rig. Results indicate a strong dependence of present microstructural phases and Hardness on the wear resistance entailed by different welding parameters. Optimised parameters and low energy input during welding leads to stable Hot Hardness progress and wear conditions for the investigated materials.

  • Welding Parameters and their Influence on the Abrasion Resistance of Structural Steels at Elevated Temperatures
    Key Engineering Materials, 2016
    Co-Authors: H. Rojacz, H. Pahr, S Baumgartner, Karl Adam, M. Varga
    Abstract:

    In several industrial applications wear resistance of structural steels is required. Also enhanced temperature can occur when handling Hot materials, e.g. in steel industry. Within this study a low alloyed structural steel (carbon steel S355) and a high temperature (HT) 9 % Cr steel ASTM A332 P92 were chosen for investigation. Repair welds with flux cored wires which are often required in applications were investigated, aiming on the role of interpass temperatures, the resulting effect of cooling conditions on the microstructure and their HT abrasion resistance. The influence of different microstructural parameters such as phase content, processing and the resulting temperature-Hardness coherence on the wear resistance are evaluated within a high temperature abrasion test and a Hot Hardness test rig. Results indicate a strong influence of interpass temperature and heat input on the Hot Hardness and wear behaviour of welded structural steels.

  • Disquisition on material parameters and their influence on wear rates at high temperatures
    2011
    Co-Authors: H. Winkelmann, M. Varga, E. Badisch
    Abstract:

    The aim of this work is to find correlations of hard phase content and matrix type with Hot Hardness and wear rates in the cyclic impact abrasion test at high testing temperatures. Several materials with different matrix types and varying hard phase content have been investigated regarding their wear behaviour as well as their Hot Hardness up to 800°C. The Hot Hardness and hard phase content then was correlated to the wear rates using statistical methods. Materials with comparable matrix properties and higher hard phase content always have higher Hot Hardness and these parameters are statistically dependent so correlation of wear rate with Hot Hardness is statistically sufficient. It was found, that within the same material the wear rate is correlated to the Hot Hardness as long as there is no significant change in the wear mechanism. When the matrix of the material changes the Hot Hardness can not be directly correlated to the wear rate any more. It was also found that among all materials tested those with an austenitic matrix generally have higher wear resistance even if they have the same Hot Hardness.

  • Impact of microstructure on high temperature wear resistance
    Procedia Engineering, 2011
    Co-Authors: M. Varga, H. Winkelmann, Ewald Badisch
    Abstract:

    Abstract In many industrial applications wear at different temperature levels causes a loss of operational reliability. In this view the wear behaviour of two different hard facings used as wear protection were investigated at ambient and elevated temperatures: a Ni-based alloy with tungsten carbide reinforcement and a carbide rich Fe-based complex alloy. The wear resistance at room temperature and elevated temperatures of 300 °C and 550 °C was investigated in impacting and abrasive environment in specially developed test equipment. Additionally the Hot Hardness was measured in a newly developed Hot Hardness Test (HHT) at different temperature levels up to 700 °C and correlated to the wear behaviour. Wear analyses were conducted by means of calculation of volume loss, optical microscopy (OM) and scanning electron microscopy (SEM) of the wear tracks, respectively. Results show, that wear rates and mechanisms at high temperature can not be directly correlated to wear at ambient temperature, also the material's microstructure has crucial influence on the wear behaviour. Hence the more expensive Ni-based alloy with tungsten carbide reinforcement does not necessarily shows better wear resistance in all environments investigated.

C. Ganguly - One of the best experts on this subject based on the ideXlab platform.

  • Hot Hardness and indentation creep studies on Zr1Nb1Sn0.1Fe alloy
    Journal of Nuclear Materials, 1997
    Co-Authors: T R G Kutty, T. Jarvis, C. Ganguly
    Abstract:

    The Hot Hardness behaviour the Zr-1Nb-1Sn-0.1Fe alloy was evaluated from room temperature to 1173 K at 100 K intervals. The Hardness versus temperature data for this alloy can be represented by the relationship H =Κexp( -BT). The indentation creep measurements of the above mentioned alloy were carried out using a load of 300 g at 573, 673, 773, 873 and 973 K. The stress exponent obtained from Hardness-time plots was found to be temperature dependent and decreases from a value of nearly 42 at 573 K to ~5 at 973 K. The activation energy for creep was also found to be temperature dependant for this alloy. At least four different domains of creep were observed in the temperature range of 573-973 K. The mechanism in the temperature regime of 573-673 K was found to be athermal

  • Evaluation of Hot Hardness and creep of a 350 grade commercial maraging steel
    Journal of Materials Science, 1996
    Co-Authors: U. K. Viswanathan, T R G Kutty, R. Keswani, C. Ganguly
    Abstract:

    The hardening response and the indentation creep of a 350 grade commercial maraging steel were evaluated using a Hot Hardness tester. The Hardness versus temperature plot exhibited three distinct regions. Hardness response was noted between 500–800 K. The unusually high values of activation energy and stress exponent obtained during the creep experiment could be rationalized by a novel concept of introducing a back stress term in the indentation creep relation. The corrected value of the activation energy was found to be reasonably in agreement with the activation energy for diffusion of Ni in iron. Results are supplemented with microstructural observation.

  • Indentation technique for evaluation of Hot Hardness and creep of SS 316 end-plug welds of nuclear, fuel pins
    Journal of Materials Science, 1992
    Co-Authors: T R G Kutty, C. Ganguly
    Abstract:

    The high-temperature mechanical properties of SS 316 end-plug welds of nuclear fuel pins were studied using a Hot Hardness tester. The Hardness was measured as a function of temperature on the base metal, weld pool and heat-affected zone from ambient temperature to 1273 K. Hardness was also measured as a function of dwell time from 873 to 1173 K to evaluate the activation energy for creep. The activation energy of the weld pool was found to be higher than that of the base metal. The indentation technique is very suitable for the evaluation of creep properties of very small components.

H. Rojacz - One of the best experts on this subject based on the ideXlab platform.

  • High temperature abrasion resistance of differently welded structural steels
    Tribology International, 2017
    Co-Authors: H. Rojacz, H. Pahr, S Baumgartner, M. Varga
    Abstract:

    Abstract Structural steels provide a broad spectrum of heat, creep and wear resistance at different microstructures and Hardness levels. Two different steel grades were chosen for investigation and simulated repair welds with different parameters were performed, aiming on the influence of heat input during welding and the resulting microstructure on the high temperature abrasion resistance. The impact on the wear resistance and its temperature dependence was evaluated within a high temperature three-body abrasion test and a Hot Hardness test rig. Results indicate a strong dependence of present microstructural phases and Hardness on the wear resistance entailed by different welding parameters. Optimised parameters and low energy input during welding leads to stable Hot Hardness progress and wear conditions for the investigated materials.

  • Welding Parameters and their Influence on the Abrasion Resistance of Structural Steels at Elevated Temperatures
    Key Engineering Materials, 2016
    Co-Authors: H. Rojacz, H. Pahr, S Baumgartner, Karl Adam, M. Varga
    Abstract:

    In several industrial applications wear resistance of structural steels is required. Also enhanced temperature can occur when handling Hot materials, e.g. in steel industry. Within this study a low alloyed structural steel (carbon steel S355) and a high temperature (HT) 9 % Cr steel ASTM A332 P92 were chosen for investigation. Repair welds with flux cored wires which are often required in applications were investigated, aiming on the role of interpass temperatures, the resulting effect of cooling conditions on the microstructure and their HT abrasion resistance. The influence of different microstructural parameters such as phase content, processing and the resulting temperature-Hardness coherence on the wear resistance are evaluated within a high temperature abrasion test and a Hot Hardness test rig. Results indicate a strong influence of interpass temperature and heat input on the Hot Hardness and wear behaviour of welded structural steels.

Min-hsiung Hon - One of the best experts on this subject based on the ideXlab platform.