| 1. |
- Esmaily, Mohsen, 1987, et al.
(författare)
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Effect of Rheocasting on Corrosion of AM50 Mg Alloy
- 2015
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 162:3, s. C85-C95
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Tidskriftsartikel (refereegranskat)abstract
- The corrosion behavior of magnesium-aluminum (Mg-Al) alloy AM50 produced by a rheocasting (RC) technique was examined in the presence and absence of CO2 at three temperatures -4, 4 and 22 degrees C. The slurry preparation in the RC material was performed with the newly developed RheoMetal process. For reference, 99.97% Mg was included in the corrosion exposures. The influence of the microstructure on the atmospheric corrosion of alloy AM50 produced by RC and high pressure die casting (HPDC) was investigated. The RC AM50 alloy showed better corrosion resistance than HPDC AM50 in all the exposure environments studied. For both materials, there was a strong positive correlation between temperature and the atmospheric corrosion rate. The superior atmospheric corrosion behavior of RC AM50 compared to HPDC AM50 is carefully discussed in relation to differences in the as-cast microstructure. This study demonstrates that producing the alloy AM50 by this type of RC technique opens the door to Mg-Al alloys as a promising candidate for various applications where corrosion resistance is of importance.
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| 2. |
- Esmaily, Mohsen, 1987, et al.
(författare)
-
Influence of temperature on the atmospheric corrosion of the Mg–Al alloy AM50
- 2015
-
Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X. ; 90, s. 420-433
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of temperature on the NaCl-induced atmospheric corrosion of the Mg–Al alloy AM50 has been investigated in the laboratory. The corroded samples were analyzed gravimetrically and by SEM, EDX, XRD, and FTIR. The atmospheric corrosion of 99.97% Mg was also studied for reference. While the NaCl-induced atmospheric corrosion of AM50 is strongly reduced with decreasing temperature, 99.97% Mg does not exhibit such a trend. The temperature dependence of the atmospheric corrosion of alloy AM50 is attributed to the aluminum content in the alloy. Several crystalline magnesium hydroxy carbonates formed at 4 and 22 °C but were absent at −4 °C.
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| 3. |
- Esmaily, Mohsen, 1987, et al.
(författare)
-
Influence of temperature on the atmospheric corrosion of the MgAl alloy AM50 produced by semi-solid cast and high pressure die cast technique
- 2013
-
Ingår i: Proceedings of the International Congress on Light Materials-Science and Technology (LightMAT 2013), Bremen, Germany, In: Characterisation, Simulation, In: Corrosion, Editor: A. Lohmüller.
-
Konferensbidrag (refereegranskat)abstract
- The effect of temperature on the atmospheric corrosion of the MgAl alloy AM50 was investigated in the laboratory. The alloy was investigated in both semi-solid cast and high pressure die cast form. Polished samples were exposed to air containing 400ppm CO2 for up to 4 weeks at 22ºC, 4ºC and -4oC at 95% relative humidity (RH). The rate of corrosion was determined by mass gain and metal loss measurements. The corrosion products were analyzed by SEM/EDX. Analysis by XRD showed that the composition of the crystalline corrosion product depended on the exposure temperature. Both materials exhibited a strong positive correlation between temperature and the rate of NaCl-induced atmospheric corrosion. It is suggested that the temperature dependence of corrosion is related to the dissolution of alumina in the passive film. The semi-solid cast material exhibited lower average corrosion rates at all three temperatures.
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| 4. |
- Frisk, Karin, et al.
(författare)
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Characterisation of EBM-built shelled samples of Ti6Al4V compacted by HIP
- 2016
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Ingår i: World PM 2016 Congress and Exhibition. - : European Powder Metallurgy Association (EPMA). - 9781899072484
-
Konferensbidrag (refereegranskat)abstract
- Compaction of additively manufactured Ti6Al4V components by Hot Isostatic Pressing (HIP) is often applied to eliminate porosity, producing fully dense material. In the present work shelled samples produced by Electron Beam Melting with the Arcam process (EBM) were compacted by HIP to produce fully dense samples. Cylindrical samples were studied. The walls of the cylinders were built with EBM, and the powder from the process was left uncompacted inside the cylinders. Samples with different wall thicknesses were produced. The samples were thereafter subjected to a HIP compaction. The critical wall thicknesses needed for compaction were evaluated, and the microstructures characterized. The results show that fully dense samples, with very fine microstructures, are possible.
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| 5. |
- Leicht, Alexander, 1987, et al.
(författare)
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As-HIP microstructure of EBM fabricated shell components
- 2016
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Ingår i: World PM 2016 Congress and Exhibition. - : European Powder Metallurgy Association (EPMA). - 9781899072484
-
Konferensbidrag (refereegranskat)abstract
- Electron Beam Melting (EBM) was used to build Ti-6Al-4V cylindrical shell samples with different wall thickness filled with powder. Built shell samples were HIPed and the difference in microstructure between the EBM-built walls and densified powder inside the shell components was studied as well as the cohesion between these two regions. Components characterization utilizing LOM and SEM+EBSD indicates that columnar grain growth was consistent before and after HIP in the EBM-built part of the components (walls), whereas the densified material in the center of the component had a fine isotropic microstructure, characteristic for HIPed material. The combination of EBM and HIP is shown to be an attractive way of manufacturing complex-shape full density components for high performance applications, involving shortening of built time in the EBM-processing and lead time in capsule fabrication for HIP.
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| 6. |
- Leicht, Alexander, 1987, et al.
(författare)
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Characterization of virgin and recycled 316L powder used in additive manufacturing
- 2016
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Ingår i: SPS16, Lund, Sweden 2016.
-
Konferensbidrag (refereegranskat)abstract
- Gas atomized 316L powder used in electron beam melting was investigated in virgin and recycled stateto indicate the influence of recycling on the powder properties. A cross sectional investigation of thepowder microstructure was performed by means of light optical microscopy and the phase compositionwas determined by means of X-ray diffraction analysis. The powder surface characterization was doneby using X-ray photoelectron spectroscopy and high resolution scanning electron microscopy equippedwith an energy dispersive X-ray analyser. Results showed that evenly distributed oxide particles in thesubmicron range can be observed on the surface of both virgin and recycled powder. The size of theseoxide features on the surface of recycled powder is on average around 200 nm which is four times largerin comparison to virgin powder which is around 50 nm. The EDX analysis indicated enrichment of Si,Cr and Mn in the oxides. According to XPS, both powders are covered by homogenous Fe-oxide layerwith particulate oxide features rich in Cr and Mn. Significantly higher amount of Cr oxide was detectedon the surface of recycled powder compared to the surface of the virgin powder. The recycled powderalso had lower Mn content on the surface. The reason for this is proposed to be the sublimation of Mn,which drives the decomposition of Mn-oxide. The powder cross-section showed that the microstructureof the recycled powder had a tendency to change towards cellular structure, while the microstructure ofvirgin powder is fully dendritic.
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| 7. |
- Lundin, Per, 1971, et al.
(författare)
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A study of the surface integrity after machining by means of non-destructive testing methods
- 2013
-
Ingår i: Proceedings of the International Conference on Advanced Manufacturing Engineering and Technologies Vol. 2. - Stockholm. - 9789175018935 ; , s. 283-292
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Konferensbidrag (refereegranskat)abstract
- During metal machining, depending on the cutting conditions, surface and subsurface microstructure alteration are occasionally observed. These alternations are normally referred as “white” and “dark” layers. Due to their different mechanical properties in comparison to the unaffected material, they will have an impact on the finished part. Controlling the quality of the machined parts regarding the surface microstructure alteration by means of non-destructive testing (NDT) methods would be beneficial from production point of view. In this study, the surface integrity of AISI 52100 steel machined at different cutting conditions resulting in white and dark layers with different characteristics were studied. Surface topography, microstructure and residual stresses were examined by using light scattering, optical microscopy and x-ray diffraction (XRD) techniques. Whilst surface characterization was emphasized, one NDT method – magnetic Barkhausen noise (BN) technique – is not well defined for this purpose. The correlation between all the applied techniques was therefore investigated and a preliminary model was developed for the influence of surface roughness, stress conditions and white and dark layer thicknesses on BN signal.
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| 8. |
- Mallipeddi, Dinesh, 1987, et al.
(författare)
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Surface integrity of machined electron beam melted Ti6Al4V alloy manufactured with different contour settings and heat treatment
- 2020
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Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 87:20, s. 327-332
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Konferensbidrag (refereegranskat)abstract
- The powder-bed-fusion-based Electron Beam Melting (EBM) is rapidly gaining interest as a feasible process in the manufacturing industry for producing intricate Ti6Al4V components. However, there is still a challenge of reducing production time and optimizing surface roughness. One way to improve surface roughness is to optimize the melting strategy, i.e. contour setting. This not only influences the obtained surface topographical features, but also the production time. Most industrial applications require subtractive post processing (machining) to obtain a desired functional surface. This paper is concerned with analysing surface and subsurface in turning of Ti6Al4V alloy, manufactured by EBM using different contour settings. Also, the effect of subsequent heat treatment, i.e. Hot Isostatic Pressing (HIP) is studied. The results indicate that avoiding of contours require a machining allowance of 1 mm to obtain surface roughness of about 0.5 µm (Sa). In case of three and five contours the machining allowance can be reduced to 0.25 mm. Microstructural differences originating from the subsequent HIP operation show no effect on machinability. Tensile residual stresses are generated when reaching down to the heat effected zone of contour settings.
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| 9. |
- Mellin, P., et al.
(författare)
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Bonding EBM-built blocks of 316L steel, using hot isostatic pressing
- 2017
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Ingår i: Proceedings Euro PM 2017: International Powder Metallurgy Congress and Exhibition. - : European Powder Metallurgy Association (EPMA).
-
Konferensbidrag (refereegranskat)abstract
- To enable production of the First Wall Beam in the ITER fusion reactor; we attempt to join EBM-built blocks of 316L, by Hot Isostatic Pressing (HIP). For highly critical components, EBM-built material is usually HIPed anyway to heal defects such as pores and cracks. Using HIP to simultaneously bond several print-jobs together into a larger component saves time and reduces manufacturing complexity. We found by carrying out this research, that fine surface roughness is an important enabler for a complete bond. The raw printed surfaces that are obtained straight from the Arcam machine (Ra = 19.2 μm) do not enable a good bond. Instead, traditional machining, which in this paper reached Ra = 2.0 μm, enabled a good bond. HIP parameters are also important. The best bond in this study was achieved after increasing holding time from 1 h to 2 h.
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| 10. |
- Nayyar, Varun, 1981, et al.
(författare)
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An Experimental Investigation of Machinability of Graphitic Cast Iron Grades; Flake, Compacted and Spheroidal Graphite Iron in Continuous Machining Operations
- 2012
-
Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 1:1, s. 488-493
-
Konferensbidrag (refereegranskat)abstract
- In this study the machinability of different grades of cast iron has been studied in terms of cutting temperatures, cutting forces, tool life, deformed chip thickness and contact length in different continuous machining operations. The tests performed were: external turning, boring and face turning. Pearlitic Flake Graphite Iron (FGI), Compacted Graphite Iron (CGI) and Spheroidal Graphite Iron (SGI) materials were selected for making the experiments. Later the machinability was also compared with ferritic SGI material. The cutting temperature has been measured with the help of thermocouple insisted inserts. These inserts were having 2 junctions; 0.55 and 1.2 mm away from the cutting edge on the clearance face. It has been seen that the cutting temperature on the clearance face has not shown any significant difference for different grades of cast irons. However, the tool life and the cutting forces have shown significant differences. The face turning tests were performed in both dry and wet conditions to see the importance of cutting fluids for different grades of cast iron. It has been seen that the CGI and SGI requires cutting fluid in a continuous machining operation. It has been seen that CGI and SGI require cutting fluid in a continuous machining operation. Later the wear mechanisms of different grades were also studied for dry and wet conditions in a boring operation. Both CGI and SGI have shown adhesion as a wear mechanism under dry conditions as compared to abrasive wear in wet conditions with a cutting speed of 300 m/min. The results can be input to designing a suitable insert for CGI and SGI and highlights the importance of using cutting fluids while machining CGI and SGI in a continuous turning operation.
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| 11. |
- Nayyar, Varun, 1981, et al.
(författare)
-
An experimental investigation of temperature and machinability in turning of compacted graphite irons
- 2012
-
Ingår i: International Journal of Materials and Product Technology. - 0268-1900. ; 43:1-4, s. 102-121
-
Tidskriftsartikel (refereegranskat)abstract
- The life and the performance of an insert in metal cutting are mainlydependent on the heat that is generated in the contact zones on the tool rakeface with chips and on the flank face with the transient and machined surfaces.According to tool life standard, the wear on the flank face is usually taken as adecision for tool life. This occurs because of contact stresses, temperature andfriction between tool workpiece contacts. Hence, knowledge of temperature onthe flank face becomes important. The temperature on the flank face hasbeen measured in this work for different CGI materials having differentmicrostructure and physical properties in a turning operation. It has been seenthat there is no significant difference of flank temperature, while machiningdifferent CGI materials having hardness from (140 to 236 HBW). Fortemperature measurement, special inserts integrated with gold-platinumthermocouple on the flank face were used. It has been noticed that the materialshaving 31% resultant cutting force difference and six to eight times tool lifedifference have almost same temperature on the flank face measured atdifferent distances from the edge line of the insert.
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| 12. |
- Nayyar, Varun, 1981, et al.
(författare)
-
An experimental investigation of temperature and machinability in turning of compacted graphite irons
- 2011
-
Ingår i: Int. J. Machining and Machinability of Materials.
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The life and the performance of an insert in metal cutting are mainlydependent on the heat that is generated in the contact zones on the tool rakeface with chips and on the flank face with the transient and machined surfaces.According to tool life standard, the wear on the flank face is usually taken as adecision for tool life. This occurs because of contact stresses, temperature andfriction between tool workpiece contacts. Hence, knowledge of temperature onthe flank face becomes important. The temperature on the flank face hasbeen measured in this work for different CGI materials having differentmicrostructure and physical properties in a turning operation. It has been seenthat there is no significant difference of flank temperature, while machiningdifferent CGI materials having hardness from (140 to 236 HBW). Fortemperature measurement, special inserts integrated with gold-platinumthermocouple on the flank face were used. It has been noticed that the materialshaving 31% resultant cutting force difference and six to eight times tool lifedifference have almost same temperature on the flank face measured atdifferent distances from the edge line of the insert.
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| 13. |
- Nayyar, Varun, 1981, et al.
(författare)
-
An Experimental Investigation of the Influence of Cutting Edge Geometry on the Machinability of Compacted Graphite Iron
- 2013
-
Ingår i: International Journal of Manufacturing, Materials, and Mechanical Engineering. - : IGI Global. - 2156-1680 .- 2156-1672. ; 3:1, s. 1-25
-
Tidskriftsartikel (refereegranskat)abstract
- Compacted graphite iron (CGI) is considered as the potential replacement of flake graphite iron (FGI) for the manufacturing of new generation high power diesel engines. Use of CGI, that have higher strength and stiffness as compared to FGI, allows engine to perform at higher peak pressure with higher fuel efficiency and lower emission rate. However, not only for its potential, CGI is of an area of interest in metal cutting research because of its poor machinability as compared to that of FGI. The higher strength of CGI causes a faster tool wear rate in continuous machining operation even in low cutting speed as compared to that for FGI. This study investigated the influence of cutting edge geometry at different cutting parameters on the machinability of CGI in terms of tool life, cutting force and surface roughness and integrity in internal turning operation under wet condition. It has been seen that the cutting edge radius has significant effect on tool life and cutting forces. The results can be used to select optimum cutting tool geometry for continuous machining of CGI.
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| 14. |
- Nayyar, Varun, 1981, et al.
(författare)
-
Machinability of Compacted Graphite Iron (CGI), a Microstructural and Mechanical Properties Comparison Approach
- 2009
-
Ingår i: Swedish Production Symposium 09.
-
Konferensbidrag (refereegranskat)abstract
- Compacted Graphite Iron (CGI) has an important role in manufacturing of new generation engines. Better strength of CGI allows engines to perform at higher pressure and also to have better efficiency with lower emission rate. The machinability of CGI is an area that needs to be studied in a better way to cut the production cost of the engine. It is a well know fact that the as-cast engine block has varying microstructure and mechanical properties due to different cooling rates at different locations of such a geometrically complex component. This has highlighted the need for studying machinability as a function of microstructural and mechanical properties so that the machining process could be optimized. For this reason, machinability of 18 different types of CGI materials along with two Gray Cast Iron (GCI) materials has been studied in turning operation. A model for relating tool life to the mechanical properties of CGI has been developed and the machinability of the different CGIs has also been compared with grey cast iron (GCI) for reference. The criteria used for comparison of machinability are tool life and cutting forces. When machining CGI, the tool life is found to decrease drastically with increase in hardness, ultimate tensile strength and pearlite content. The highest tool life is almost 6 times of the least tool life noticed out for the 18 different types of CGI. The best tool life given by CGI is still almost half of that for the GCI reference material, although the force value measured for GCI was comparatively higher than for some of the CGI materials.
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| 15. |
- Nayyar, Varun, 1981, et al.
(författare)
-
Machinability of Compacted Graphite Iron (CGI) and Flake Graphite Iron (FGI) with coated carbide
- 2013
-
Ingår i: International Journal of Machining and Machinability of Materials. - 1748-5711 .- 1748-572X. ; 13:1, s. 67-90
-
Tidskriftsartikel (refereegranskat)abstract
- Compacted Graphite Iron (CGI) has an important role in manufacturing of new generation engines. Better strength of CGI, as compared to flake graphite iron (FGI), allows CGI engine to perform at higher peak pressure. This can give higher fuel efficiency and lower emission rate. However, the machinability of CGI is poor as compared to FGI. The machinability of CGI is an area that needs to be studied in a better way to cut the production cost of the engine. It is a well known fact that the as-cast engine block has varying microstructure and mechanical properties due to different cooling rates at different locations of such a geometrically complex component. This has highlighted the need for studying machinability as a function of microstructural and mechanical properties so that the machining process could be optimized. For this reason, machinability of 18 different types of CGI materials along with two FGI materials has been studied in turning operation. The criteria used for comparison of machinability were tool life and cutting forces. A model for relating tool life to the mechanical properties of CGI has been developed and the machinability of the different CGIs has also been compared with flake graphite iron (FGI). A model for resultant cutting force as a function of mechanical properties and cutting parameters has been developed. It has been seen that, while machining CGI and FGI, the tool life is found to decrease drastically with increase in hardness, ultimate tensile strength and pearlite content. The highest tool life is almost 6 times of the least tool life noticed out for the 18 different types of CGI. The best tool life given by CGI is still almost half of that for the FGI materials used for comparison, although the force value measured for FGI was comparatively higher than from the ferritic CGI materials.
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| 16. |
- Nayyar, Varun, 1981, et al.
(författare)
-
Temperature in Turning of Compacted Graphite Iron Materials having different Physical properties and Microstructure
- 2011
-
Ingår i: Swedish Production Symposium.
-
Konferensbidrag (refereegranskat)abstract
- The life and the performance of an insert in metal cutting are mainly dependent on theheat that is generated in the contact zone on the tool rake and on the flank face with thetransient and machined surfaces. According to tool life standard the wear on the flankface is usually taken as a decision for tool life. Hence knowledge of temperature on theflank face becomes important. The temperature on the flank face has been measured inthis work for different CGI materials having different microstructure and physical propertiesin a turning operation. It has been seen that there is no significant difference of tooltemperature noticed while machining different CGI materials having hardness from (140-236 HBW). For temperature measurement, special inserts assisted with gold-platinumthermocouple on the flank face were used. It has been noticed that the materials having31% resultant force difference and 8-6 times tool life difference have almost sametemperature on the flank face measured at different distances from the edge line of theinsert.
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| 17. |
- Shahabi Navid, Mehrdad, 1986, et al.
(författare)
-
NaCl-induced atmospheric corrosion of MgAl alloy AM50 in semi-solid cast and high pressure die cast form; relation between alloy microstructure and corrosion
- 2013
-
Ingår i: Proceedings of the International Congress on Light Materials-Science and Technology (LightMAT 2013), Bremen, Germany, In: Characterisation, Simulation, In: Corrosion, Editor: A. Lohmüller.
-
Konferensbidrag (refereegranskat)abstract
- The atmospheric corrosion behavior of the MgAl alloy AM50 has been investigated in the laboratory, in the presence of 0, 14 and 70µg/cm2 NaCl. The alloy was investigated both as high pressure die cast and in semi-solid cast (rheocast) form. Polished samples were exposed for 1-672h in air at constant temperature (22.00oC) and constant relative humidity (95%). The concentration of CO2 was 0 or 400ppm. Corrosion rate was determined by measuring mass gain and metal loss. The microstructure of the two materials was examined through optical microscopy and SEM/EDX analyses. Cross sections were prepared through the corroded samples using focused ion beam (FIB) milling. The corrosion products were characterized by SEM/EDX and X-ray diffraction. The rheocast material was observed to exhibit better corrosion resistance than the high pressure die cast alloy. The relation between alloy microstructure and corrosion attack for the two materials is reported and discussed.
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| 18. |
- Shahabi Navid, Mehrdad, 1986, et al.
(författare)
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NaCl-Induced Atmospheric Corrosion of the MgAl Alloy AM50-The Influence of CO2
- 2014
-
Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 1945-7111 .- 0013-4651. ; 161:6, s. C277-C287
-
Tidskriftsartikel (refereegranskat)abstract
- The NaCl-induced atmospheric corrosion of the MgAl alloy AM50 has been investigated using 99.97% Mg as reference. Polished samples were exposed up to 672 h in 95.0% RH air with 400 ppm or 0 ppm CO2 at 22.00°C. Samples were analyzed gravimetrically and by SEM/EDX, XRD and XPS. CO2 inhibited atmospheric corrosion with alloy AM50 corroding 6–7 times faster in the absence of CO2. Brucite and meixnerite (Mg6Al2(OH)18 × 4.5H2O) formed in the absence of CO2. In the presence of CO2 and NaCl three magnesium-hydroxy-carbonates, giorgiosite, hydromagnesite and Mg5(CO3)4(OH)2 × 8H2O formed. The influence of CO2 on the electrochemical corrosion process is discussed.
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| 19. |
- Tasdelen, Bulent, 1980, et al.
(författare)
-
An Experimental Study to Understand the Effect of Cooling Media at Metal Cutting
- 2007
-
Ingår i: Maunsrcipt Elsevier- CIRC.
-
Tidskriftsartikel (refereegranskat)abstract
- Dry and Semi-Dry machining has gained interest in the last years because of the new environmental legislations and the possibility to decrease the machining cost. However, the role of cutting media such as emulsion, compressed air and Minimum Quantity Lubrication (MQL) on the chip formation has not been understood yet. The mechanical and thermodynamical conditions in the cutting zone affects the properties of work piece material under cutting and these conditions change with the application of cutting media. In this work a medium alloyed forged steel was machined with assistance of emulsion, MQL and only compressed air and the results are compared to dry machining in terms of chip colour, micro structure, white-etching band and contact area between chip and the insert rake face. It was observed that white-etching band, which is believed to be ferrite, forms both on the chip upper free side and chip back side for all conditions. In emulsion cutting, this band has finest grains and with dry cutting it has largest grains proving a slower cooling with dry cutting. Not a big difference was observed on white-etching band when MQL, compressed air and dry machining are compared. However, it was observed that cooling ability of MQL and compressed air has affected the contact area when the media was applied on rake face.
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| 20. |
- Tasdelen, Bulent, 1980, et al.
(författare)
-
An Experimental Study to Understand the Effect of Cooling Media in Metal Cutting
- 2011
-
Ingår i: International Conference on Materials Science, Metal & Manufacturing (M3 2011).
-
Konferensbidrag (refereegranskat)abstract
- Dry and Semi-Dry machining has gained interest in the last years because of the new environmental legislations and the possibility to decrease the machining cost. However, the role of cutting media such as emulsion, compressed air and Minimum Quantity Lubrication (MQL) on the chip formation has not been understood yet. The mechanical and thermo dynamical conditions in the cutting zone affects the properties of work piece material under cutting and these conditions change with the application of cutting media. In this work medium alloyed forged steel was machined with assistance of emulsion, MQL and only compressed air and the results were compared to dry machining in terms of chip color, micro structure, white-etching band and contact area between chip and the insert rake face. It was observed that white-etching band, which is believed to be ferrite, forms both on the chip upper free side and chip back side for all conditions. In emulsion cutting, this band has finest grains and with dry cutting it has largest grains proving a slower cooling with dry cutting. Not a big difference was observed on white-etching band when MQL, compressed air and dry machining were compared. However, it was observed that thermo-mechanical effect of air in MQL and compressed air supply has affected the contact area when the media was applied on rake face.
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| 21. |
- Alzati, L., et al.
(författare)
-
PM parts sintered state improvement achieved by carbon source selection
- 2013
-
Ingår i: 2013 International Conference on Powder Metallurgy and Particulate Materials, PowderMet 2013. - 9780985339739 ; , s. 516-524
-
Konferensbidrag (refereegranskat)abstract
- In this work primary synthetic graphite, natural graphite and carbon black as carbon sources for PM parts sintering are compared. In order to highlight the different behaviour in demanding applications, special focus is on Cr-alloyed PM steels. Interrupted sintering trials have been run on specimens that were analysed both by advanced techniques (HR SEM, EDX) and Light Optical Microscopy, highlighting how sintering process rate can be positively affected by carbon source selection. Confirmation from tests run on Iron-Copper-Carbon is also presented. Implications for production of different typologies of PM parts is are also discussed. Test results on Key properties like Dimensional Stability (within one lot and lot-to-lot), Mechanical Performance (in terms of macro-Hardness, Tensile Rupture Strength) and solid-state Lubrication are also displayed.
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| 22. |
- Ananthanarayanan, Durga, et al.
(författare)
-
Grain refinement in additively manufactured ferritic stainless steel by in situ inoculation using pre-alloyed powder
- 2021
-
Ingår i: Scripta Materialia. - : Elsevier BV. - 1359-6462 .- 1872-8456. ; 194
-
Tidskriftsartikel (refereegranskat)abstract
- For ferritic stainless steels, TiN has effectively been used as an inoculant to produce equiaxed grain structures in casting and welding. However, it is not established whether TiN would be an effective inoculant in additive manufacturing. In this study, the effectiveness of TiN as an inoculant in a ferritic stainless steel processed by laser powder-bed fusion is studied. An alloy without Ti is fabricated and compared to an alloy designed to form a high amount of TiN early during solidification. The work shows that the presence of TiN provides general grain refinement and that TiN-covered oxide particles are effective in enabling columnar-to-equiaxed transition in certain regions of the meltpool. The applied approach of pre-alloying powders with inoculant-forming elements offers a straightforward route to achieving fine, equiaxed grain structures in additively manufactured metallic materials. It also shows how oxygen present during the process can be utilized to nucleate effective inoculating phases.
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| 23. |
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| 24. |
- Bengtsson, S., et al.
(författare)
-
New Aluminium Alloy Tailored For Powder Bed Fusion - Laser Beam Process
- 2022
-
Ingår i: World PM 2022 Congress Proceedings.
-
Konferensbidrag (refereegranskat)abstract
- The powder bed fusion - laser beam (PBF-LB) process can produce parts with complex geometry. Light weight designs can be created and by using light alloys further weight savings can be achieved. However, minimizing printing defects using standard aluminium alloys, such as 2000, 6000 and 7000 series alloys, have proved to be difficult since they are all prone to solidification cracking. In the present study, two aluminium alloys are addressed: The first alloy is the AlSi10Mg alloy known for easy printing and consistent quality in PBF-LB printing process. The second material is a novel alloy from self-developed Al-Mn-Cr-Zr family of alloys designed to inherently resist solidification cracking, while also providing strong ageing response. The quality of printing and the resulting mechanical properties are compared. The results show that the new material prints in a robust way and that the mechanical properties are superior to those of AlSi10Mg.
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| 25. |
- Bergman, Ola, et al.
(författare)
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Analysis of oxide reduction during sintering of Cr-alloyed steel powder through photoacoustic spectroscopy measurements
- 2009
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Ingår i: Proceedings of the Euro International Powder Metallurgy Congress and Exhibition, Euro PM 2009. - : European Powder Metallurgy Association (EPMA). - 9781899072088 ; 3
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Konferensbidrag (refereegranskat)abstract
- The usage of steel powders prealloyed with chromium in PM components for high performance applications is steadily increasing. Excellent mechanical properties are achieved with these powder grades, provided that the processing into components is accurately done. Photoacoustic spectroscopy (PAS) technique has been used here to study oxide reduction during sintering in 90N2/10H2 atmosphere of test specimens based on 3%Cr-0.5%Mo prealloyed powders with 0.5% C added. Results from performed reduction trials show that Fe oxides on the powder surfaces are removed by H2 reduction early in the heating stage of the process. Carbothermal reduction is the main mechanism for reduction of stable Cr-containing oxides from 900°C and above. Efficient Cr oxide reduction requires a sintering temperature of at least around 1200°C. Therefore, small oxide particles remain in the material after sintering at 1120°C for 30 minutes. However, such oxides have earlier been shown to have no significant influence on mechanical properties.
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