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I Manna - One of the best experts on this subject based on the ideXlab platform.
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structure property correlation in laser surface treated aisi H13 Tool Steel for improved mechanical properties
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2014Co-Authors: G Padmanabham, G. Telasang, Dutta J Majumda, I MannaAbstract:Abstract The present study concerns laser surface hardening (LSH) and melting (LSM) of AISI H13 Tool Steel using a high power continuous wave diode laser. Depth of surface hardened or melted layer increases with increase in incident laser energy density. Surface melting occurs at a higher laser energy density (>75 J/mm 2 ) and leads to the formation of inhomogeneous microstructure comprising non-uniform distribution of retained austenite, carbides (along inter-dendritic boundary) and martensite with their respective volume fractions varying with depth. Application of intermediate laser energy density (50–75 J/mm 2 ) yields a hardened layer with dispersion of ultrafine mixed carbides (M 23 C 6 , M 7 C 3 , MC or M 2 C). Laser treatment with a very low laser energy density ( 2 ) leads to formation of an over-tempered microstructure consisting of low carbon martensite and coarse carbide precipitates. Micro-tensile studies with specially machined samples from the surface melted zone following LSM with a laser energy density of 100 J/mm 2 records a high yield strength of 1310 MPa along with poor ductility, marked by brittle failure. On the other hand, a similar sample from laser surface hardened zone treated with a laser energy density of 62.5 J/mm 2 yielded even higher yield strength of 1460 MPa with a maximum elongation of 3.6%. Though both LSH and LSM produced higher yield strength compared to hardened and tempered AISI H13 Tool Steel, LSH yielded a combination of higher elongation (3.6%), than that after LSM (0.97%), with high yield strength and hence was considered a better option.
Andre Paulo Tschiptschi - One of the best experts on this subject based on the ideXlab platform.
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structural and mechanical characterization of duplex multilayer coatings deposited onto H13 Tool Steel
Journal of materials research and technology, 2012Co-Authors: Abel Andre Cândido Recco, Andre Paulo TschiptschiAbstract:Quenched and tempered H13 Tool Steel was plasma nitrided and Physical Vapour Deposition (PVD) coated in a hybrid reactor aiming to obtain a TiN/TiC multilayer coating deposited on a plasma nitrided substrate, with a more gentle transition of elastic-plastic properties between the outermost layer of the coating and the substrate. Duplex treatment (plasma nitriding and PVD coating) was carried out in a hybrid reactor. Plasma nitriding preceded the DC triode magnetron sputtering PVD process, conducted inside the same chamber, using CH 4 and N 2 as reactive gases. Multilayer TiN/TiC coatings deposited on a nitrided H13 substrate were obtained. The multilayer coating was composed by a first Ti interlayer to grant adhesion, followed by a second 18.4 at% C TiC layer with a cF8 NaCl type unit cell, then a 41.9 at% N TiN layer and finally an outermost 32.3 at% C TiC layer with the same cF8 NaCl type unit cell. The multilayer coating showed a gentle transition of elastic-plastic properties assessed by the H/E * and the H 3 /E *2 ratios and the elastic recovery as a function of the distance from the surface of the specimen. The adhesion of the multilayered coating to the substrate was greater in the case of the duplex coated specimen as compared to the non duplex treated H13 Steel.
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adhesion of reactive magnetron sputtered tinx and ticy coatings to aisi H13 Tool Steel
Surface & Coatings Technology, 2007Co-Authors: Abel Andre Cândido Recco, I C Oliveira, M Massi, Homero Santiago Maciel, Andre Paulo TschiptschiAbstract:Reactive Magnetron Sputtered TiN and TiC films were deposited on AISI H13 Tool Steel and silicon (111) substrates, under nitrogen and argon or methane and argon reactive plasma. Depth sensing techniques were used to assess the mechanical properties of the films, namely hardness and Young modulus using a load of 7.0 mN. TiN and TiC were deposited using a magnetron sputtering technique, the amount of nitrogen in the sputtering gas being changed from 3 to 38 vol.% and the amount of methane from 2 vol.% to 27 vol.%. The H/E ratio (Hardness/Young Modulus) of TiN films increases continuously when the amount of nitrogen in the sputtering gas is increased from 3 to 38 vol.%. For TiC films the ratio H/E reached a maximum for a methane content of 12 vol.% in the sputter gas. The film to substrate adhesion was measured using Rockwell C tests. The adhesion of the film to the substrate was greater when the H/E ratio of the film and of the substrate were similar. © 2007 Elsevier B.V. All rights reserved.
T Ngoc - One of the best experts on this subject based on the ideXlab platform.
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deposition of superhard tialsin thin films by cathodic arc plasma deposition
Surface & Coatings Technology, 2005Co-Authors: P V Vinh, T NgocAbstract:Thin films of TiAlSiN were deposited on AISI H13 Tool Steel substrate using Ti and AlSi cathodes by a cathodic arc plasma deposition system. The influence of the nitrogen pressure, AlSi cathode arc current, bias voltage, and deposition temperature on the mechanical and the structural properties of the films were investigated. The hardness of the film decreased with the increase of nitrogen gas pressure. The hardness of the film increased with the increase of AlSi cathode arc current and the bias voltage. The hardness of the film reached 48 GPa at the deposition temperature of 300 °C and decreased with a further increase of the temperature. Wear and scratch tests were performed on thin films deposited in various conditions. The critical load of the films was above 50 N.
G. Telasang - One of the best experts on this subject based on the ideXlab platform.
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microstructure and mechanical properties of laser clad and post cladding tempered aisi H13 Tool Steel
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2015Co-Authors: G. Telasang, G Padmanabham, Jyotsna Dutta Majumda, Niti P Waseka, Indranil MannaAbstract:This study reports a detailed investigation of the microstructure and mechanical properties (wear resistance and tensile strength) of hardened and tempered AISI H13 Tool Steel substrate following laser cladding with AISI H13 Tool Steel powder in as-clad and after post-cladding conventional bulk isothermal tempering [at 823 K (550 °C) for 2 hours] heat treatment. Laser cladding was carried out on AISI H13 Tool Steel substrate using a 6 kW continuous wave diode laser coupled with fiber delivering an energy density of 133 J/mm2 and equipped with a co-axial powder feeding nozzle capable of feeding powder at the rate of 13.3 × 10−3 g/mm2. Laser clad zone comprises martensite, retained austenite, and carbides, and measures an average hardness of 600 to 650 VHN. Subsequent isothermal tempering converted the microstructure into one with tempered martensite and uniform dispersion of carbides with a hardness of 550 to 650 VHN. Interestingly, laser cladding introduced residual compressive stress of 670 ± 15 MPa, which reduces to 580 ± 20 MPa following isothermal tempering. Micro-tensile testing with specimens machined from the clad zone across or transverse to cladding direction showed high strength but failure in brittle mode. On the other hand, similar testing with samples sectioned from the clad zone parallel or longitudinal to the direction of laser cladding prior to and after post-cladding tempering recorded lower strength but ductile failure with 4.7 and 8 pct elongation, respectively. Wear resistance of the laser surface clad and post-cladding tempered samples (evaluated by fretting wear testing) registered superior performance as compared to that of conventional hardened and tempered AISI H13 Tool Steel.
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Effect of laser parameters on microstructure and hardness of laser clad and tempered AISI H13 Tool Steel
Surface & Coatings Technology, 2014Co-Authors: G. Telasang, G Padmanabham, J. Dutta Majumdar, M. Tak, Indranil MannaAbstract:Abstract In the present study, laser cladding of AISI H13 Tool Steel powder has been undertaken on hardened and tempered AISI H13 Tool Steel components using a 6 kW fiber coupled diode laser both in continuous wave and pulsed mode with coaxial powder feeder to explore the possibility of reclamation/refurbishment of large AISI H13 Tool Steel components. Laser parameters in terms of laser power, processing speed and powder feed rate have been optimized to achieve acceptable clad-substrate integrity with optimum deposition height and width without any surface cracks and porosity. A detailed study of the effect of post-cladding heat treatment (both by laser assisted surface heating and conventional tempering at 550 °C) on the microstructure, phase aggregate, crystallite size, micro-strain and residual stress was carried out. Subsequently, the microhardness of the clad zone was evaluated. Pulsed laser cladding (heat input controlled) with 50 Hz frequency and 50% duty cycle with 10 ms ON-time developed a microstructure comprising martensite, retained austenite and mixed carbides. The maximum improvement in hardness (considered as a convenient index of strengthening) by laser cladding reached up to 650 VHN, which is about 45% higher than the hardness of hardened and tempered substrates. Post-cladding tempering at 550 °C for 2 h led to the development of uniform microstructure without fine carbide precipitated along grain boundaries or inter-dendritic regions taking the hardness to 600–650 VHN level. Laser reheating (tempering) of the clad zone with a 1000 W laser power showed a more refined microstructure with maximum hardness up to 680–700 VHN. Residual stress, developed on the surface after laser cladding, was compressive in nature and measured higher in magnitude after pulsed laser cladding. Magnitude of this residual compressive stress marginally decreased after post-cladding tempering either by conventional or laser assisted route. Thus, the novelty of the present study lies in the continuous or pulsed mode laser cladding assisted reclamation of AISI H13 hot working dies with similar composition powder, followed up with conventional or laser assisted tempering, leading to the development of about 45% higher hardness (than as hardened and tempered conditions) and retention of residual compressive stress on the surface after cladding.
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structure property correlation in laser surface treated aisi H13 Tool Steel for improved mechanical properties
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2014Co-Authors: G Padmanabham, G. Telasang, Dutta J Majumda, I MannaAbstract:Abstract The present study concerns laser surface hardening (LSH) and melting (LSM) of AISI H13 Tool Steel using a high power continuous wave diode laser. Depth of surface hardened or melted layer increases with increase in incident laser energy density. Surface melting occurs at a higher laser energy density (>75 J/mm 2 ) and leads to the formation of inhomogeneous microstructure comprising non-uniform distribution of retained austenite, carbides (along inter-dendritic boundary) and martensite with their respective volume fractions varying with depth. Application of intermediate laser energy density (50–75 J/mm 2 ) yields a hardened layer with dispersion of ultrafine mixed carbides (M 23 C 6 , M 7 C 3 , MC or M 2 C). Laser treatment with a very low laser energy density ( 2 ) leads to formation of an over-tempered microstructure consisting of low carbon martensite and coarse carbide precipitates. Micro-tensile studies with specially machined samples from the surface melted zone following LSM with a laser energy density of 100 J/mm 2 records a high yield strength of 1310 MPa along with poor ductility, marked by brittle failure. On the other hand, a similar sample from laser surface hardened zone treated with a laser energy density of 62.5 J/mm 2 yielded even higher yield strength of 1460 MPa with a maximum elongation of 3.6%. Though both LSH and LSM produced higher yield strength compared to hardened and tempered AISI H13 Tool Steel, LSH yielded a combination of higher elongation (3.6%), than that after LSM (0.97%), with high yield strength and hence was considered a better option.
P. T. Mativenga - One of the best experts on this subject based on the ideXlab platform.
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environmental performance evaluation of different cutting environments when milling H13 Tool Steel
Journal of Cleaner Production, 2015Co-Authors: Ismet Hari Mulyadi, Vince A Alogu, P. T. MativengaAbstract:Abstract Limited availability of natural resources and the negative environmental burden of industrial processes are driving environmental awareness and resource efficiency improvements in manufacturing. Issues of concern in mechanical machining arise from the significant use of electrical energy and oil-based coolants/lubricants. Process innovation through high speed machining has enabled manufacturing cycle times to be reduced and in some cases promoted dry machining or the use of minimum quantity lubrication. However, the environmental assessment of these innovations has hardly been explored. In this study, the environmental benefits of minimum quantity lubrication environments in machining Tool Steel at transition speed regime through electrical energy consumption were evaluated and compared to its competitors. The work then assessed the energy using a customized electrical energy model proposed in this study and hence the environmental performance in the process level. Tool life might be of concern in selecting between MQL, dry machining and flood machining, however, this study found that in respect to total energy requirement and environmental benefits, MQL is more promising than flood machining. The work is fundamentally important in assessing the direct energy consumption and the environmental credentials of machining processes.
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White layer formation and hardening effects in hard turning of H13 Tool Steel with CrTiAlN and CrTiAlN/MoST-coated carbide Tools
The International Journal of Advanced Manufacturing Technology, 2007Co-Authors: A. Aramcharoen, P. T. MativengaAbstract:White layers are hard, brittle and normally associated with a tensile stress and hence the ability to reduce the fatigue life of machined components. Several authors have reported the formation of white layers on components after turning processes by using CBN/PCBN and ceramic cutting Tools. However, there are hardly any studies that have reported on white layer formation for new and low-cost-coated carbides. The study in this paper was conducted to determine the effect of CrTiAlN and CrTiAlN+MoST and high cutting speeds on white layer formation in machining Tool Steel. H13 Tool Steel (57 HRC) was examined after turning at a conventional and high cutting speed. Coated Tools resulted in lower workpiece and Tool temperatures. Hence coated Tools resulted in reduced and also more homogeneous hardening effects compared to the uncoated Tool. In addition, the higher cutting speed produced negligible white layers. Thus, the paper elucidates on the benefits of coatings on surface hardening in conventional and high speed machining.
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white layer formation in hard turning of H13 Tool Steel at high cutting speeds using cbn Tooling
International Journal of Machine Tools & Manufacture, 2006Co-Authors: S S Osheh, P. T. MativengaAbstract:White layers formed during machining have negative effects on surface finish and fatigue strength of products. The white layer is generally a hard phase and leads to the surface becoming brittle causing crack permeation and product failure. This is a major concern with respect to service performance especially in the aerospace and automotive industries. Numerous authors have investigated the formation of white layer under different manufacturing processes. In turning, it was suggested that the white layer structure is a martensitic phase whose formation is correlated to Tool wear. Past studies have tended to concentrate on the formation of white layers at conventional cutting speeds, but never examined the formation at high cutting speeds. This paper reports on an investigation of white layer formation for wide range of cutting speeds in hard turning of 54-56 HRC H13 Tool Steel. The specimens were analysed using a micro hardness tester, SEM with EDAX software and Electron Micro-Probe. In addition Tool wear and workpiece temperature were studied. The machined surface showed an increase in hardness with respect to the bulk material. Compositional gradients were noted for the white layer in terms of depletion of the elements iron and chromium coupled with an enrichment of carbon and oxygen content. The results showed that despite Tool wear increasing with cutting speed, white layer depth and hardness actually reduced. This finding suggests that there may not be a direct relationship between white layer formation and wear, the correlation maybe linked to wear mode.
