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Doostmohammadi, HamidORCID iD iconorcid.org/0000-0003-1779-8728
Publications (8 of 8) Show all publications
Adineh, M. & Doostmohammadi, H. (2019). Microstructure, mechanical properties and machinability of Cu-Zn-Mg and Cu-Zn-Sb brass alloys. Materials Science and Technology, 35(12), 1504-1514
Open this publication in new window or tab >>Microstructure, mechanical properties and machinability of Cu-Zn-Mg and Cu-Zn-Sb brass alloys
2019 (English)In: Materials Science and Technology, ISSN 0267-0836, E-ISSN 1743-2847, Vol. 35, no 12, p. 1504-1514Article in journal (Refereed) Published
Abstract [en]

Lead-free alloys have attracted great attentions recently due to the toxic nature of lead for the human body. In this study, low amounts of Mg and Sb were added to the Cu65-Zn35 brass and microstructure, mechanical properties and machinability of samples were compared to Cu65-Zn35 brass. Both Mg and Sb led to the promotion of beta ' phase as well as the formation of new ternary copper rich intermetallic particles. It was found that these particles had a significant role in the reduction of the ultimate tensile strength, toughness, work hardening and elongation while increasing the hardness of samples. Results of machinability evaluation of samples showed that the cutting forces were decreased significantly and morphology of chips were improved compared to Cu65-Zn35 brass sample.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2019
Keywords
Microstructure characterisation, lead-free brass, magnesium, antimony, mechanical properties, machinability, cutting forces, intermetallic particles
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-255182 (URN)10.1080/02670836.2019.1630089 (DOI)000472361400001 ()2-s2.0-85067619916 (Scopus ID)
Note

QC 20190904

Available from: 2019-09-04 Created: 2019-09-04 Last updated: 2019-09-04Bibliographically approved
Yousefi, M. & Doostmohammadi, H. (2019). Spatial and microstructural dependence of mechanical properties and wear performance of functionally graded Al-TiAl3 in situ composite. SN APPLIED SCIENCES, 1(10), Article ID UNSP 1190.
Open this publication in new window or tab >>Spatial and microstructural dependence of mechanical properties and wear performance of functionally graded Al-TiAl3 in situ composite
2019 (English)In: SN APPLIED SCIENCES, ISSN 2523-3963, Vol. 1, no 10, article id UNSP 1190Article in journal (Refereed) Published
Abstract [en]

Effect of morphology and spatial distribution ofTiAl(3) particles on the hardness, the tensile behavior and the wear performance of functionally graded Al-TiAl3 in situ composite (FGC) was investigated. Initially, FGC was produced by interaction between solid Ti and liquid Al. Based on the spatial distribution and morphology of TiAl3 particles in the microstructure of FGC, three distinctive regions including blocky-particle region, mixed-particle region (blocky and short plate particles) and lengthy plate-particle region were studied. Results of this study showed that the blocky-particle region had promoted tensile strength as well as highly improved wear resistance. In addition, this region with higher density of blocky particles and low interparticle spacing showed a brittle fracture. The mixed-particle region with a lower density of blocky particles had a ductile fracture mechanism while the plate-particle region showed cleavage fracture.The dominant wear mechanism for regions including blocky particles was determined to be mild oxidation while it was delamination wear for regions containing plate particles. Finally, correlation between mechanical properties, wear resistance and microstructure of FGC was discussed.

Place, publisher, year, edition, pages
SPRINGER INTERNATIONAL PUBLISHING AG, 2019
Keywords
Microstructure, Mechanical properties, Wear resistance, Functionally graded Al-TiAl3 in situ composite, Particle spatial distribution, Morphology
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-262955 (URN)10.1007/s42452-019-1217-6 (DOI)000489305900001 ()
Note

QC 20191203

Available from: 2019-12-03 Created: 2019-12-03 Last updated: 2019-12-03Bibliographically approved
Doostmohammadi, H., Karasev, A. & Jönsson, P. G. (2010). A Comparison of a Two-Dimensional and a Three-Dimensional Method for Inclusion Determinations in Tool Steel. STEEL RES INT, 81(5), 398-406
Open this publication in new window or tab >>A Comparison of a Two-Dimensional and a Three-Dimensional Method for Inclusion Determinations in Tool Steel
2010 (English)In: STEEL RES INT, ISSN 1611-3683, Vol. 81, no 5, p. 398-406Article in journal (Refereed) Published
Abstract [en]

To produce clean commercial tool steel the non-metallic inclusions characteristics have to be known, since they influence the mechanical properties of steel. In this work, inclusion characteristics in steel samples from plant trials were studied. The samples were collected in the steel plant according the two following methods: (a) 2D investigations of inclusions by a cross sectional method and (b) 3D investigations of inclusions collected on a film filter after electrolytic extraction. More specifically, the chemical composition, morphology, number and size distribution of inclusions in tool steel samples taken from ladle during melt treatment were determined by both methods. In both methods SEM equipped with EDS was used for compositional analysis of inclusions. In addition, in the cross sectional method an automated detection program called 'INCAFeature' was used to collect more statistics of non-metallic inclusions. The composition of inclusions larger than 5 mu m was found to contain 49% CaO based on the results from both methods. However, for smaller inclusions it was found that the accuracy of the 2D method was less than that of the 3D method due to the influence of the metal matrix on the results. In addition, it was found that a critical inclusion size of 4 mu m could be defined for the 3D method, above which the standard deviation in composition determination was very low.

Keywords
steel cleanness, cross sectional method, electrolytic extraction, INCAFeature, LADLE TREATMENT, DEOXIDATION PRODUCTS, ALLOY, AL, ZR, TI
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-14041 (URN)10.1002/srin.200900149 (DOI)000278292200010 ()2-s2.0-77953921873 (Scopus ID)
Note
QC 20100709Available from: 2010-07-09 Created: 2010-07-09 Last updated: 2011-03-04Bibliographically approved
Doostmohammadi, H., Jönsson, P., Komenda, J. & Hagman, S. (2010). Inclusion Characteristics of Bearing Steel in a Runner after Ingot Casting. STEEL RES INT, 81(2), 142-149
Open this publication in new window or tab >>Inclusion Characteristics of Bearing Steel in a Runner after Ingot Casting
2010 (English)In: STEEL RES INT, ISSN 1611-3683, Vol. 81, no 2, p. 142-149Article in journal (Refereed) Published
Abstract [en]

In the uphill teaming method of ingot casting molten metal from the ladle goes into the runner system, which feeds one or several ingot moulds. This method is still important for production of bearing steel. In order to make clean steel, which has a controlled amount of inclusions, good understanding of inclusions characteristics is necessary In this work non-metallic inclusions of steel left in the runner part of an ingot casting system were studied. Inclusion type, size, and morphology were the main focus of this study A scanning electron microscope (SEM) was used to assess inclusion size and morphology The chemical composition of inclusions was determined by SEM equipped with EDS. An automated program called 'INCAFeature' was used to collect statistics of inclusion characteristics. Based on the statistical analysis of inclusion composition, four types of inclusions including oxides, sulfides, carbonitrides and complex inclusions were defined. The inclusion characteristics in the runner were also compared to literature data of inclusions found in ladle and mould samples.

Keywords
ingot, inclusions, runner, casting, microscopy, steel, CARBON STEEL
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-14044 (URN)10.1002/srin.200900106 (DOI)000275142400007 ()2-s2.0-77949439737 (Scopus ID)
Note
QC 20100709Available from: 2010-07-09 Created: 2010-07-09 Last updated: 2011-01-24Bibliographically approved
Doostmohammadi, H., Andersson, M., Karasev, A. & Jönsson, P. (2010). Use of Computational Thermodynamic Calculations in Studying the Slag/Steel Equilibrium during Vacuum Degassing. STEEL RES INT, 81(1), 31-39
Open this publication in new window or tab >>Use of Computational Thermodynamic Calculations in Studying the Slag/Steel Equilibrium during Vacuum Degassing
2010 (English)In: STEEL RES INT, ISSN 1611-3683, Vol. 81, no 1, p. 31-39Article in journal (Refereed) Published
Abstract [en]

The effectiveness of a ladle refining process for production of tool steel with focus on the top slag is studied using computational thermodynamic calculations. The theoretical assessment was based on compositional data of steel and slag samples collected during trials in a plant equipped with a 65-t EAF, a ladle furnace and a vacuum degasser The calculation of slag-metal equilibrium during ladle treatment was performed for top slag excluding (Case A) and including (Case B) slag carryover and deoxidation products. The predictions showed that slag carryover and deoxidation products in the ladle significantly affect the composition of the top slag. Thus, these conditions must be taken into consideration when predicting the actual top slag composition. It was also found that it is possible to predict the final aluminium and sulphur content in steel based on the same calculation approach.

Keywords
ladle slag, computational thermodynamics, tool steel, ladle refining, synthetic slag, ladle glaze, slag carryover, SULFIDE CAPACITY, SLAG COMPOSITION, STEEL PRODUCTION, MOLTEN STEEL, METAL, DESULFURIZATION
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-14039 (URN)10.1002/srin.200900112 (DOI)000274847200006 ()2-s2.0-77949472636 (Scopus ID)
Note
QC 20100709Available from: 2010-07-09 Created: 2010-07-09 Last updated: 2011-03-04Bibliographically approved
Doostmohammadi, H. (2009). A Study of Slag/Metal Equilibrium and Inclusion Characteristics during Ladle Treatment and after Ingot Casting. (Doctoral dissertation). Stockholm: KTH
Open this publication in new window or tab >>A Study of Slag/Metal Equilibrium and Inclusion Characteristics during Ladle Treatment and after Ingot Casting
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Today, there is a high demand on clean steel for high performance materialproperties. Thus, steel producers try to deliver a steel product with the highestquality and cleanliness to the market. The number of parameters that affect thesteel cleanliness may vary depending on the required material properties of thefinal product. However, the non-metallic inclusion characteristics represent one ofthe most important parameters. More specifically, the composition, size, numberand morphology affect steel cleanliness. In this work, selected parameters affectingthe inclusion characteristics were studied using the following methods: i)thermodynamic calculations (including computational thermodynamiccalculations), ii) inclusion determinations using a cross sectional (CS) method (2Dinvestigations) and iii) inclusion determinations using an electrolytic extraction(EE) method (3D investigations).

The computational thermodynamic calculations of the slag-steel and inclusion-steelequilibriums were carried out using the Thermo-Calc software. With the help ofthese calculations, the influence of the slag carryover on the top slag, aluminumcontent in steel and sulfur distribution ratio as well as predictions of stable phasesof inclusions were studied. In addition, inclusion determinations of tool steel gradesamples collected during various stages of the ladle treatment in a scrap-based steelplant were carried out using both 2D and 3D methods. Furthermore, inclusiondeterminations of bearing steel grade samples from a runner system after ingotcasting were performed using a 2D metallographic method (CS-method). Also, theINCAFeature software was used, when using cross sectional method, in order tocollect more statistics of the inclusion characteristics.

It was found that slag carryover has a large influence on the composition of theactual top slag as well as the aluminum content in the steel as well as the sulfurdistribution ratio. In addition, steel and slag were found to be in “near”-equilibriumconditions, after the completion of the vacuum degassing operation. Furthermore,the composition of small-size inclusions in samples taken from tool steel was foundto be very scattered. Moreover, the composition of the large-size inclusions wasfound to be less scattered. Furthermore, closer to the top slag composition insamples collected after vacuum degassing. Finally, the accuracy of the inclusioncomposition determinations of tool steel samples using the electrolytic extractionmethod was found to be better than for the cross sectional method. The worseaccuracy of the CS-method is due to a considerable effect of matrix elements oninclusion composition.

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. p. x, 57
Keywords
inclusions, thermodynamics, ladle treatment, vacuum, tool steel, bearing steel, slag, equilibrium, slag carryover, oxides, sulfides.
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-11596 (URN)978-91-7415-520-4 (ISBN)
Public defence
2009-12-17, F3, Lindstedtsvägen 26, KTH, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
QC 20100709Available from: 2009-12-03 Created: 2009-11-21 Last updated: 2010-07-09Bibliographically approved
Doostmohammadi, H., Andersson, M. A. T., Steneholm, K. & Jönsson, P. (2009). Effect of EAF Slag Carryover on Slag-metal Equilibrium Calculations for Ladle Degassing Process. In: Howard SM (Ed.), EPD CONGRESS 2009, PROCEEDINGS   . Paper presented at Symposium on Extraction and Processing Division held at the TMS 2009 Annual Meeting and Exhibition, San Francisco, CA, FEB 15-19, 2009 (pp. 695-702).
Open this publication in new window or tab >>Effect of EAF Slag Carryover on Slag-metal Equilibrium Calculations for Ladle Degassing Process
2009 (English)In: EPD CONGRESS 2009, PROCEEDINGS    / [ed] Howard SM, 2009, p. 695-702Conference paper, Published paper (Refereed)
Abstract [en]

During the tapping of liquid steel from Electric Arc Furnace (EAF), some slag is carried over into the ladle. High levels of FeO and MnO in slag carryover increase the oxygen activity in steel melt leading to oxide inclusion formation during the ladle treatment. The demand on cleaner steels requires minimization of carryover slag. In this work, the effect of EAF slag carryover on ladle slag-steel equilibrium calculations for a hot working tool steel was studied. Steel and slag sampling were done in Uddeholm Tooling AB in Sweden. XRF and OES techniques were used to determine chemical composition of samples. The quantity of slag carryover was calculated based on a mass balance followed by thermodynamic calculations on metal-slag equilibrium using Thermo-Calc software. The agreement between predictions and experimentally determined compositions was good. This leads to the development of a prediction method for optimizing the production of other tool steel grades.

Series
EPD CONGRESS, ISSN 1079-7580
Keywords
Slag carryover, Thermodynamic calculations, Tool steel, Vacuum degassing
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-31218 (URN)000264751400082 ()2-s2.0-67449139077 (Scopus ID)978-0-87339-732-2 (ISBN)
Conference
Symposium on Extraction and Processing Division held at the TMS 2009 Annual Meeting and Exhibition, San Francisco, CA, FEB 15-19, 2009
Note
QC 20110324Available from: 2011-03-24 Created: 2011-03-11 Last updated: 2011-03-24Bibliographically approved
Doostmohammadi, H., Andersson, M., Karasev, A. & Jönsson, P. G.Thermodynamic and Experimental Considerations of the Inclusion Characteristics during Vacuum Degassing of Tool Steel.
Open this publication in new window or tab >>Thermodynamic and Experimental Considerations of the Inclusion Characteristics during Vacuum Degassing of Tool Steel
(English)Manuscript (preprint) (Other (popular science, discussion, etc.))
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-14043 (URN)
Note
QC 20100709Available from: 2010-07-09 Created: 2010-07-09 Last updated: 2011-03-04Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1779-8728

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