Hardenability of steels for oil industry

• Autorzy: Gojic, M. , Kosec, B. , Anzel, I. , Kosec, L. , Preloscan, A.
• Języki publikacji: EN

Abstrakty

EN

Purpose: Alloying elements in steels are used for a various reasons. One of the most important is the achievement of higher strength in required shapes and sizes. Often in very large sections of steels are used for production of the oil country tubular goods (OCTG). Therefore the hardenability of steels is an important property aim for the appropriate concentration of alloying elements needed to harden the section of steel for oil industry. In this study the hardenability, the cooling rates and microstructures of low alloy Cr-Mo and Mn-Mo steels were investigated. Design/methodology/approach: The cooling rate determines the amount of martensite structure. Hardenability test was carried out by Jominy method. During Jominy testing the temperature changes were monitored by means of CrNi-Ni thermocouples which are connected to eight-channel digital/analogues converter. Microstructure was determined using a scanning electron microscopy (SEM). Findings: The cooling rates in the temperature range between 1133 and 973 K at different distances from the quenched end of low alloy Cr-Mo and Mn-Mo steels were found. Also the hardness and microstructures against the distances from quenched end are determined. Research limitations/implications: It is known that carbon has a marked the effect on hardenability of steel, but its use at higher levels is limited because lower toughness and increased probability of distortion and cracking during heat treatment and welding. Addition of manganese at low alloy steels is very useful for improvement of their hardenability. Practical implications: Chemical composition of low alloy steels for oil industry is usually complex and defined in most cases by standard which give range of concentration of the important alloying elements (Cr, Mo, Mn, etc.) as well as the upper limits of impurity elements (S and P). Alloying elements increase the cost of the steel and from these reason it is important to select only steels which required to ensure compliance with specifications. The economical way of increasing the hardenability of steels (at constant carbon content) is to increase the manganese content. Originality/value: Originality and high value of our research work based on development and application of a new grade of low alloy Mn-Mo steel for oil country tubular goods.

Słowa kluczowe

PL

stal; hartowność; próba Jominy'ego; szybkość chłodzenia

EN

steel; hardenability; Jominy test; cooling rate

• Czasopismo: Journal of Achievements in Materials and Manufacturing Engineering
• Rocznik: 2007
• Tom: Vol. 23, nr 2
• Strony: 23-26
• Opis fizyczny: Bibliogr. 17 poz., fot., rys., tab.

Twórcy

autor

Gojic, M.

autor

Kosec, B.

autor

Anzel, I.

autor

Kosec, L.

autor

Preloscan, A.

• Faculty of Metallurgy, University of Zagreb, Aleja Narodnih Heroja 3, 44-103 Sisak, Croatia,

Bibliografia

• [1] B. Liscic, H.M. Tensi, W. Luty, Theory and technology of quenching, Springer-Verlag, Berlin, 1991.
• [2] G. Kraus, Steels heat treatment and processing principles, ASM International, New York, 1990.
• [3] E.K. Thelning, Steel and its Heat Treatment, Butterworths. London, 1984.
• [4] G.E. Totten, M.A.H. Howes, Steel Heat Treatment, Marcel Dekker, New York, 1997.
• [5] M. Gojic, A. Preloscan, M. Malina., Hardenability testing of low-alloy chromium steels modified with molibdenium and niobium, Metallurgy 30/4 (1991) 161-165 (in Croatian).
• [6] J.V. Tuma, J. Kranjc, The temperature distribution in the superheater tube, forschung in ingenieurwessen, Engineering Research 66/4 (2001) 153-156.
• [7] B. Smoljan, An analysing of heat treatment process planning, Journal of Achievements in Materials and Manufacturing Engineering 20 (2007) 563-566.
• [8] B. Smoljan, N. Tomasic, D. Iljkic, I. Felde, T. Reti, Application of JM®-test in 3D simulation of quenching, Journal of Achievements in Materials and Manufacturing Engineering 17 (2006) 281-284.
• [9] L.A. Dobrzanski, W. Sitek, Designing of the chemical composition of constructional alloy steels, Journal of Materials Processing Technology 89/90 (1999) 467-472.
• [10] J. Trzaska, L.A. Dobrzanski, Application of neural networks for selection of steel with the assumed hardness after cooling from the austenitising temperature, Journal of Achievements in Materials and Manufacturing Engineering 16 (2006) 145-150.
• [11] J. Trzaska, W. Sitek, L.A. Dobrzanski, Selection method of steel grade with required hardenability, Journal of Achievements in Materials and Manufacturing Engineering 20 (2007) 471-474.
• [12] B. Smoljan, An analysis of combined cyclic heat treatment performance, Journal of Materials Processing Technology 155/11 (2004) 1704-1707.
• [13] ASTM A255-99, ASTM. Pittsburgh, 1999.
• [14] Methods of determining hardenability of steels, SAE J406, SAE Handbook. Vol. 1, Society of Automative Engineers, Warrendale 1995.
• [15] F. Pavlin. B. Kosec. M. Bizjak. M.C. Ferfolja, Temperature profile measurements on wellman type annealing furnace, RMZ - Materials and Geoenvironment 46/1 (1999) 83-87.
• [16] B. Kosec, M. Bizjak, Upgrade of the system for the hardenability testing of steels with the system for the temperature measurements, Euroteh 3/3 (2004) 28 (in Slovene).
• [17] M Gojic, L. Lazic, B. Kosec, M. Bizjak, Application of mathematical modelling to hardenability testing of low alloyed Mn-Mo steel, Strojarstvo 47/3-4 (2005) 101-108.