Microstructural Characterisation of 1.2080 Steel Modified With

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Journal of the University of Chemical Technology and Metallurgy, 47, 3, 2012, 327-332 MICROSTRUCTURAL CHARACTERISATION OF 1.2080 STEEL MODIFIED WITH NANO-DISPERSED Si 3 N 4 PARTICLES AFTER VARIOUS HEAT TREATMENTS B. Yordanov University of Chemical Technology and Metallurgy 8 Kl. Ohridski, 1756 Sofia, Bulgaria E-mail: [email protected] ABSTRACT Results from a metallographic study of the microstructure of 1.2080 tool steel with and without modifying additions of silicon nitride (Si 3 N 4 ), after various applied heat treatments are obtained. Distribution of the phases (ledebur eutectic, alloyed martensite, retained austenite and dispersed carbides) and hardness in samples from 1.2080 steel after applied 35% plastic deformation and modifying with silicon nitride have been observed. Keywords: 1.2080 steel, metallographic microstructure, modifying, silicon nitride, heat treatment. Received 12 March 2012 Accepted 12 May 2012 INTRODUCTION The modern industry has an increasing need for large amounts of complicated tools with various dimensions, shapes and applications. Steels with an appropriate composition and properties must be used in order to increase the in-service life of these tools. The requirements for the tool steels, such as 1.2080 steel, are quite high and extensive knowledge is needed either for the development or for their application in an attempt to completely satisfy the requirements for the tools with specific application [1]. Depending on their application the tool steels are classified as follows: - steels for cutting tools; - steels for measuring tools; - steels for dies. The most important technological properties of the tool steels are: - reduced sensitivity to overheating, reduced distortion and cracks formation during quenching; - low decarburatization rate and good sanding ability; - increased strength and high fracture toughness. The 1.2080-type steels are used mainly for pro- duction of stamping dies. By stamping the desired shape of the manufactured products is achieved without cutting and only by plastic deformation of the metal inside the stamping die. The stamping could be made at low or elevated temperatures. The efficiency of the stamping processes is quite high and the stamped details have quite good accuracy in their dimensions. The savings in metal waste are considerable and the economical effectiveness of the mass production processes is increased. The 1.2080- type tool steels are mainly used for cold stamping dies, drawing plates, rollers, cutters, trimming stamps, etc. Such tools must have higher hardness, strength and ductility in comparison to the shaped metal. Because of the high friction forces, high wear resistance is also required in order to maintain the correct geometry of the tool. For dies working on impact, the fracture toughness is a very important characteristic [2-4]. The final properties of the tools are formed by heat treatment which assures the formation of micro- structures capable to withstand the high loading condi- tions during the exploitation of the tool [5, 6]. The aim of this paper is to present some results from the metallographic study of the microstructure of 1.2080 tool steel with and without modifying additions of silicon nitride (Si 3 N 4 ) after various applied heat treatments. EXPERIMENTAL The material chosen for the experiments was a standard tool steel 1.2080 [7], with or without modifying addition of nano-dispersed Si 3 N 4 . The chemical com-

Transcript of Microstructural Characterisation of 1.2080 Steel Modified With

  • B. Yordanov

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    Journal of the University of Chemical Technology and Metallurgy, 47, 3, 2012, 327-332

    MICROSTRUCTURAL CHARACTERISATION OF 1.2080 STEEL MODIFIED WITHNANO-DISPERSED Si3N4 PARTICLES AFTER VARIOUS HEAT TREATMENTS

    B. Yordanov

    University of Chemical Technology and Metallurgy8 Kl. Ohridski, 1756 Sofia, BulgariaE-mail: [email protected]

    ABSTRACT

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    Received 12 March 2012Accepted 12 May 2012

    INTRODUCTION

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    RESULTS AND DISCUSSION

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    Fig. 1. Shape and dimensions of the cast ingots.

    Fig. 2. Shape and dimensions of the cut samples.

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    Fig. 3. Heat treatment of 1.2080 steel.

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    Fig. 4. As-cast microstructure of sample 1: Primary dendritesfrom transformed alloyed austenite (white zones) andledeburite eutectic are (dark zones). Optical micrograph ofan etched sample, at magnification 100x.

    Fig. 5. As-cast microstructure of sample 2. Optical micrographof an etched sample, at magnification 100x.

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    Fig. 6. Microstructure of sample 3 without addition of Si3N4 after 35 % deformation and annealing at 870C for 180 min.Optical micrograph of an etched sample at magnification 160x (a) and 800x (b).

    Fig. 7. Microstructure of sample 4 with Si3N4 addition after 35 % plastic deformation and annealing at 870C for 180 min.Optical micrograph of an etched sample at magnification of 160x (a) and 400x (b).

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