Steel Authority of India

About: Steel Authority of India is a based out in . It is known for research contribution in the topics: Microstructure & Ultimate tensile strength. The organization has 797 authors who have published 661 publications receiving 9958 citations. The organization is also known as: SAIL.

Effect of fatigue damage on the dynamic fracture toughness of En-8-grade steel

Abstract: Machine components normally experience fatigue cycling during operation. Failure of these components is mostly due to fatigue. So, it is important to know the fatigue damage behavior and fatigue life of the material before selecting these steels for making different machine components. The En-8-grade (equivalent to SAE/AISI 1040) steel is generally used as a machine component in the annealed or hardened-and-tempered condition. The fatigue life (fatigue/endurance limit) is also dependent upon the tensile properties of any material. By suitable heat treatment, one can manipulate the tensile properties of any steel. The present work reports the effect of fatigue damage in En-8-grade heattreated steel (annealed and hardened and tempered), under different cyclic loading conditions at room temperature (25 °C), on the impact and dynamic fracture-toughness properties. The results indicate higher fracture toughness and impact toughness in hardened-and-tempered steel than in annealed steel. Cyclic hardening and softening occurs in both the hardened-and-tempered as well as the annealed steel. With the increase of peak stress and number of fatigue cycles, the KID and CVN values decrease in hardened-and-tempered steels. The results are discussed in terms of dislocations, slip bands, and their density, microstructure, and fracture morphology.

Microstructure and Oxidation Characteristics of Laser and GTAW Weldments in Austenitic Stainless Steels

Abstract: The present investigation reports microstructure and high-temperature oxidation behavior of GTAW and laser weldments of 316L stainless steel. The microstructure and oxidation behavior of composite laser weldment are found to be influenced by the welding speed. In GTAW weldment, weld metal shows higher oxidation rate as compared to base metal of same weldment. Furthermore, the inoculation of Ce in GTAW weld influences the microstructure and oxidation characteristics. The scale morphologies, scale adherence, and spallation have been characterized by SEM and EDAX.

Effectiveness of Faradic and Russian currents on plantar flexor muscle spasticity, ankle motor recovery, and functional gait in stroke patients.

Abstract: BACKGROUND AND PURPOSE Spasticity is a major disabling symptom in patients post stroke. Though studies have demonstrated that electrical stimulation (ES) can reduce spasticity and improve passive ankle range of motion (ROM), not many studies have evaluated the effectiveness of ES on active ankle ROM. The purpose of this study was to determine the effectiveness of Faradic and Russian currents in the reduction of ankle plantar-flexor spasticity and improving motor recovery in patients post stroke. METHODS Eighty-three patients (29 females and 54 males; mean age of 57.12 years) were randomly assigned to Group 1 (task-oriented exercises), Group 2 (Faradic current for 10 min and task-oriented exercises), and Group 3 (Russian current for 10 min and task-oriented exercises) for a period of 5 sessions per week for 6 weeks. All patients were assessed for soleus and gastrocnemius muscles spasticity measured by modified modified Ashworth scale; active and passive range ROM measured by goniometer; and functional ambulation measured by modified Emory Functional Ambulation Profile at the time of recruitment to study and after 6 weeks. RESULTS Both the types of stimulation and exercises were not associated with improvements in modified Emory Functional Ambulation Profile (p > 0.05). The results showed that all the groups are effective in improving passive ankle ROM (p < 0.05) and reducing soleus and gastrocnemius muscles spasticity (p < 0.05). Though all the groups were effective in improving active ankle ROM, no group was found to be superior to another after treatment CONCLUSION: Adding ES to exercises are associated with low to medium effect sizes (<0.5) in reducing spasticity and improving ankle ROM.

A new Burg method based approach to MCSA for broken rotor bar detection

Abstract: This paper presents a new approach to Motor Current Spectral Analysis (MCSA) for broken rotor bar detection. Said approach consists of applying the Discrete Fast Fourier Transform on stator current data of a three-phase induction motor, and analyzing the amplitude spectrum obtained for characteristic broken rotor bar sidebands. The difference from traditional techniques is borne out by the very short time window over which the stator current is sampled, which enables early detection of broken bars. This short-time current data is extrapolated to a longer time window using signal modeling and prediction via the Burg method, thus mitigating the shortcomings of the DFFT over short data windows. The spectrum of the extrapolated signal shows adequate frequency resolution for effective fault detection.

Uniaxial Ratcheting Behavior of a Weather-Resistant Rail Steel: Effect of Mean Stress and Stress Amplitude

Abstract: Uniaxial ratcheting behavior of a weather-resistant rail steel belonging to 60 kg/m 90-UTS variety was studied in true stress control mode with varying mean stress (σm) and stress amplitude (σa) at constant σa and σm, respectively. In all the loading conditions, the ratcheting strain (er) increased almost monotonically and accumulation of ratcheting strain was found to increase at higher magnitude of σm or σa, perhaps due to the increase in remnant dislocation density in the substructure of the investigated steel. After the initial sharp fall in ratcheting strain rate with elapsed cycles in all the cases, a constant ratcheting rate was attained very soon; thereafter, the ratcheting strain kept on accumulating in the specimen at this constant rate till the failure of the specimen occurred. It was quite interesting to see that on increasing the mean stress level at a fixed stress amplitude, after the initial decrease, fatigue life of the steel improved marginally owing to the effect of mean stress-induced hardening. In absolute contrast, under the influence of stress amplitude at a fixed mean stress, fatigue life of the rail steel deteriorated gradually but to a significant extent. Finally, stress amplitude was found to have more severe effect than that offered by the mean stress in terms of` ratcheting strain accumulation and fatigue life of the investigated rail steel.