Modification of Cr-Mo low alloyed steels by addition of Mn via mechanical milling

• Autorzy: Sicre-Artalejo J. , Campos M. , Torralba J. M.
• Języki publikacji: EN

Abstrakty

EN

Purpose: The PM industry is in continuous development due to the necessity to increase its potential and competitiveness. This fact and the demand for substituting certain alloying elements used so far, require the addition of new alloying elements and new processes leading to and optimization of costs, strength and tolerances. A different method for introducing Mn into the alloying system is proposed in the present work. Mechanically-blending and mechanically alloying Mn containing master alloys are generated and based on three different steels grades, ASC100.29 (plain iron), Astaloy CrL and Astaloy Mo (pre-alloyed systems). Design/methodology/approach: To profit Mn sublimation effects, small Mn particles, in order to increase the specific surface available to sublimate, must be homogenously added. Different milling times are considered in order to attain the desired master alloys containing 50% of Mn which is diluted in each base powder by normal mixing. New alloying systems were then pressed to a green density of 7.1 g/cm3 and sintered at 1120 ° C in 90N2-10H2 atmosphere. STA showed Mn diffusion during sintering and a densification enhancement. Findings: The sublimation of Mn during sintering provides some specific phenomena which facilitate the sintering of alloying elements with high oxygen affinity. The resulting mechanical properties and the microstructures must be discussed considering the high energy stored in the master alloy which favours the mass transport mechanism during sintering. Research limitations/implications: Research is being continued with the optimisation of the mechanical properties and the application of heat treatments taking the profit of the increase of the hardenability induced by Mn. Originality/value: Mn seems a viable substitute for alloy elements used so far in PM, such as Ni and Mo. Following European regulations Ni cannot be used in its elemental powder form because of its effects on health and Mo has increased its price in the last years.

Słowa kluczowe

EN

powder metallurgy; mn addition; master alloys

PL

metalurgia proszków; domieszka manganu

• Wydawca: International OCSCO World Press
• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2008
• Tom: Vol. 28, nr 2
• Strony: 199--202
• Opis fizyczny: Bibliogr. 15 poz., wykr.

Twórcy

autor

Sicre-Artalejo J.

autor

Campos M.

autor

Torralba J. M.

• Department of Materials Science and Engineering, Universidad Carlos III, Avda. Universidad 30 28911 Leganés-Madrid, Spain,

Bibliografia

• [1] A. Salak, Sintered manganese steels 1: Effect of structure of initial iron upon mechanical properties, Powder Metallurgy International 12 (1980) 72-75.
• [2] A. Salak, Manganese vapor-protection of premixed manganese steels against oxidation during sintering, Powder Metallurgy International 18 (1986) 266-270.
• [3] H. Danninger, Secondary porosity in Sintered steels and its effects on product quality and consistency, Powder Metallurgy 30 (1987) 103-109.
• [4] H. Danninger, Sintering of Mo Alloyed P/M Structural-steels, Powder Metallurgy International 20 (1988) 7-11.
• [5] M. Campos, S. Kremel, T. Marcu Puscas, Y. Yu, D. Sánchez, J. M. Torralba, Effect of heat treatments on Cr-Mo steels based on Astaloy CrM powder grade with Mn additions, Matererials Science Forum 416-418 (2003) 82-88.
• [6] H. Danninger, R. Pottschacher, S. Bradac, A. Salak, J. Seyrkammer, Comparison of Mn, Cr adn Mo alloyed sintered steels prepared from elemental powders, Powder Metallurgy 48 (2005) 23-32.
• [7] H. Danninger, D. Spoljaric, B. Weiss, Microstructural features limiting the performance of P/M Steels, International Journal of Powder Metallurgy 33/4 (1997) 43-47.
• [8] F. S. LePera, Improved etching technique to emphasize martensite and bainite in high strength dual phase steels, Journal of Metals 32 (1980) 38-39.
• [9] H. Danninger, Sintering of Mo Alloyed P/M Steels Prepared from Elemental Powders 2, Mo homogenization and Dimensional Behaviour, Powder Metallurgy International 24 (1992) 163-168.
• [10] A. Cias, S. C. Mitchell, K. Pilch, H. Cias, M. Sulowski, A. S. Wronski, Tensile properties of Fe-3Mn-0.6/0.7C steels sintered in semiclosed containers in dry hydrogen, nitrogen and mixtures thereof, Powder Metallurgy 46 (2003) 165-170.
• [11] C. Suryanarayana, Bibliography on mechanical alloying and milling. Cambridge International Science Publishing, Cambridge, 1995.
• [12] H. Danninger, C. Gierl, Processes in PM steels compacts during the initial stages of sintering, Materials Chemistry and Physics 67 (2001) 49-55.
• [13] E. Dudrova, M. Kabatova, R. Bidulsky, A. S. Wronsky, Industrial processing, microstructures and mechanical properties of Fe-(2-4)Mn(-0.85Mo)-(0.3-0.7)C sintered steels, Powder Metallurgy 47 (2004) 181-190.
• [14] H. K. D. H. Bhadeshia, E. Kaen, L. Karlsson, H. O. Andren, Coalesced Bainite, Transactions of the Indian Institute of Metals 59 (2006) 689-694.
• [15] S. Chatterjee, H. K. D. H. Bhadeshia, Transformation induced plasticity assisted steels: stress or strain affected martensitic transformation?, Materials Science and Technology 23 (2007) 1101-1104.