| 1. |
- Basu, A., et al.
(författare)
-
Laser surface hardening of austempered (bainitic) ball bearing steel
- 2007
-
Ingår i: Scripta Materialia. - 1359-6462 .- 1872-8456. ; 56:10, s. 887-890
-
Tidskriftsartikel (refereegranskat)abstract
- This study concerns laser surface hardening (LSH) of austempered SAE 52100 steel to enhance hardness and wear resistance. Following LSH with selected laser parameters, surface microstructure and mechanical properties were evaluated by optical/scanning electron microscopy, X-ray diffraction, hardness measurement and wear studies, and thermal profile modeling. The results suggest that LSH could develop residual compressive stress and high hardness and wear resistance in this steel without affecting the bainitic core. © 2007 Acta Materialia Inc.
|
|
| 2. |
|
|
| 3. |
- Bhardwaj, Sanjay, et al.
(författare)
-
Technology commercialization in advanced materials sector : Indian context
- 2017
-
Ingår i: Journal of Intellectual Property Rights. - 0971-7544 .- 0975-1076. ; 22:3, s. 154-167
-
Tidskriftsartikel (refereegranskat)abstract
- This study is aimed at developing insights into the Technology Value Chain (TVC) of advanced materials-based technologies using a scenario in which technology has been transferred by a Research and Technology Organization (RTO) to a Small and Medium Enterprise (SME) in the Indian context. A Conceptual Theoretical Model (CTM) using constructs from existing TVC models is used as a basis for the case study described in this paper. This model is refined using actual evidence from an Indian RTO - the International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad. The TVC of ARCI’s proprietary Detonation Spray Coating (DSC) technology is used to expand upon the CTM as well as to provide new insights wherever possible. The TVC adopted for DSC includes technology incubation and proof of concept in advance of transferring the technology. These strategies, aided by government funding of the technology recipient companies, were observed to play an important role in successful commercialization. © 2017, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.
|
|
| 4. |
- Shariff, S. M., et al.
(författare)
-
Comparative Study on Dry Sliding Wear Behavior of Various Railroad Steels
- 2011
-
Ingår i: Journal of tribology. - 0742-4787 .- 1528-8897. ; 133:2, s. 9-
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding the wear behavior of various railroad steels used in different components such as rails, wheels, crossings, and curves has a direct impact on the performance of the rail-wheel system in railroad technology. In the present investigation, the wear behavior of steels having varying microstructures (pearlite, ferrite-pearlite, austenite, and bainite) and different chemical compositions has been studied, utilizing a ball-on-disk sliding tribometer under prototypic load and dry conditions. Results indicate that the wear performance of the steel and the mechanism responsible for its wear are significantly governed by the microstructure as well as changes that occur in the contact region during sliding. The formation of tribo-particles comprising oxides of Fe and their possible smearing resulted in high wear resistance in pearlitic steels with considerable plastic deformation of ferrite lamellae compared with austenitic and bainitic steels. In the case of bainitic steel, the absence of any significant smearing of oxide debris, combined with the presence of some distributed tungsten from the ball, contributed to severe wear. On the other hand, in the case of austenitic steel, third-body abrasion by debris particles, comprising a mix of hard metallic and oxide particles, contributed to severe wear despite its high work-hardening ability. On the whole, the pearlitic steel exhibited superior wear resistance with a lower friction coefficient compared with the bainitic and austenitic steels. [DOI:10.1115/1.4003485]
|
|
| 5. |
- Shariff, S. M., et al.
(författare)
-
Influence of chemical composition and prior microstructure on diode laser hardening of railroad steels
- 2013
-
Ingår i: Surface & Coatings Technology. - 0257-8972 .- 1879-3347. ; 228, s. 14-26
-
Tidskriftsartikel (refereegranskat)abstract
- Diode laser surface treatment of three different railroad steels, namely pearlitic railroad-rail steel (PRS), ferritic-pearlitic railroad-wheel steel (FPRS) and bainitic railroad-rail steel (BRS), has been investigated. Power-ramping experiments, with in-situ surface temperature measurement, were initially carried out to assess surface temperature effects on treated layers. Influence of laser energy on characteristics of treated layers like surface topology, case-depth, microstructure and micro-hardness was comprehensively analyzed. Results revealed that the hardened layer depth is governed by both the process parameters as well as the nature of the substrate steel. With melting, significant reduction in hardness was noted owing to an increase in residual austenite and coarsening of martensitic microstructure. Unlubricated dry-sliding wear tests performed under close to real rail/wheel conditions revealed substantial improvement in wear resistance of hardened/melted rail steels compared to the parent substrates. The observed differences in characteristics of the laser-treated layers and their tribological behavior have been correlated with the chemistry and prior microstructure of the parent substrates. (C) 2013 Elsevier B.V. All rights reserved.
|
|
| 6. |
- Shariff, S. M., et al.
(författare)
-
Sliding wear behaviour of laser surface modified pearlitic rail steel
- 2010
-
Ingår i: Surface Engineering. - 0267-0844 .- 1743-2944. ; 26:3, s. 199-208
-
Tidskriftsartikel (refereegranskat)abstract
- Improving wear resistance of rails has a direct impact on the performance of rail-wheel system in railroad technology. Enhancement of sliding wear resistance at curved track, where factors such as adhesion, high slip ratios and contact fatigue act at contact patch of rail-wheel system, is particularly desirable. In the present investigation, influence of laser surface modification on sliding wear performance of a pearlitic rail steel (used in Indian railways) under two different conditions, namely, laser hardening (without any melting involved) and laser melting (with thin surface layer melting), has been studied under laboratory conditions. Before sliding wear testing, the effect of laser scanning speed on the treated layer depth has been optimised, utilising a 9 kW CO2 laser system. Sliding wear tests were carried out using a pin-on-disc device, with laser treated and untreated pearlitic rail steel discs and sliding pins made of wheel steel material, tungsten carbide (WC) and high speed steel (HSS). The tests were performed under normal prototypic loads and unlubricated conditions. Microhardness in the laser melted layer was in the range of 830-900 HV as against 890-1070 HV in the hardened layer, and was found to depend on the laser scanning speed. Sliding wear resistance of both hardened and melted layers was found to be significantly improved compared to untreated rail steel. The coefficient of friction was also marginally reduced in the laser surface melted layers.
|
|
