Własności i struktura infiltrowanych kompozytów stal szybkotnąca-węglik wolframu-miedź, Część 2

• Autorzy: Madej M. , Leżański J.

Warianty tytułu

EN

The properties and structure of infiltrated high speed steel-tungsten carbide-copper composites, Part 2

• Języki publikacji: PL

Abstrakty

PL

Przedstawiono wyniki badań w zakresie badania struktury infiltrowanych kompozytów stal szybkotnąca-węglik wolframu--miedź. Materiał badawczy stanowiły kształtki ze stali szybkotnącej gatunku M3/2 i stali szybkotnącej z dodatkiem 10 i 30 % węglika wolframu WC. Porowate kształtki przeznaczone do infiltracji prasowano pod ciśnieniem 800 MPa, część z nich poddano spiekaniu w piecu próżniowym w temperaturze 1150 stopni Celsjusza przez 60 min. Następnie porowate kształtki spiekane i niespiekane infiltrowano miedzią, metodą nakładkową w piecu próżniowym w temperaturze 1150 stopni Celsjusza przez 15 minut.

EN

High hardness, mechanical strength, heat resistance and wear resistance of M3/2 grade high speed steel (HSS) make it an attractive material for manufacture of valve train components. In this application, the material must exhibit resistance to oxidation, high hot strength and hardness, and superior wear resistance. Metal matrix composites are usually produced by the infiltration technique. Infiltration is a process that has been practiced for many years. It is defined as a process of filling the pores of a sintered or unsintered compact with a metal or alloy of a lower melting point. In the particular case of copper infiltrated iron and steel compacts, the base iron matrix, or skeleton, is heated in contact with the copper alloy to a temperature exceeding the melting point of the copper, normally to between 1095 and 1150 degrees of Celsius. Since technological and economical considerations are equally important, infiltration of high-speed steel based skeleton with liquid cooper has proved to be a suitable technique whereby fully dense material is produced at low cost. The aim of the present study was to produce high speed steel-tungsten carbide-copper composites, which should have acceptable density, wear resistance and good sliding prosperities. Various amounts of WC powder were added to the HSS powder prior to compaction. The following compositions were investigated: 100 % M3/2, M3/2 + 10 % WC and M3/2 + 30 % WC. The mixtures were prepared by mixing for 30 minutes in the 3-D pendulum motion Turbula/R T2C mixer. Then the powders were cold pressed in a rigid cylindrical die at 800 MPa. Both green compacts and pre-sintered compacts (pre-sintering condition: 1150 degrees of Celsius in vacuum for 60 minutes) were infiltrated with copper. The infiltration process was carried out in vacuum better than 10/-3 Pa. Preweighed preforms of copper were carefully placed on top of the rigid skeletons in which porosity were predetermine heated up to 1150 degrees of Celsius, subsequently held at temperature for 15 minutes and cooled down with the furnace to the room temperature. The dilatometer was used to detect some reaction in the sintering. The changes in as pressed, as sintered and as infiltrated structure are discussed in this work. From the microstructural observations (Figs 3 and 4) it may be concluded that the morphologies of capillaries are mainly affected by the manufacturing route and powder characteristics. It can be seen that the microstructure of the M3/2 grade HSS based composites consists of a steel matrix with finely dispersed carbides and islands of copper. Figure 5 shows tungsten carbides located within the grains and on the grain boundaries as well. The qualitative EDX analysis revealed the presence of both MC type vanadium-rich carbides and M6C type tungsten and iron rich carbides. The SEM and EDX analysis performed on the specimens containing 10 and 30 % tungsten carbide have revealed the carbide phase evenly distributed within the copper-rich regions. As it is apparent from Fig. 8, WC reacts with the surrounding HSS matrix and forms a tungsten and iron-rich M6C carbide grain boundary network. From the microstructural observations and obtained results it may be concluded that the infiltration with copper almost completely eliminates porosity.

Słowa kluczowe

PL

stal szybkotnąca; węglik wolframu; miedź; prasowanie; spiekanie; infiltracja; kompozyty; własności

EN

infiltration; high-speed steel; tungsten carbide; copper; pressing; sintering; composites; properties

• Wydawca: Wydawnictwo SIGMA-NOT
• Czasopismo: Rudy i Metale Nieżelazne
• Rocznik: 2008
• Tom: R. 53, nr 9
• Strony: 564--573
• Opis fizyczny: Bibliogr. 9 poz., rys., tab., wykr.

Twórcy

autor

Madej M.

autor

Leżański J.

• Akademia Górniczo-Hutnicza, Wydział Inżynierii Metali i Informatyki Przemysłowej, Katedra Metaloznawstwa i Metalurgii Proszków, Kraków

Bibliografia

• 1. Greetham G.: Mechanically locked sintered valve seat inserts. Metal Powder Report, t. 44, nr 2, s. 34.
• 2. Greetham G.: Development and performance of infiltrated and non-infiltrated valve seat insert materials and their performance. Powder Metallurgy, 1990, t. 33, nr 3, s. 112-124.
• 3. Palma R. H.: Tempering response of copper alloy infiltrated T15 high speed steel. The International Journal of Powder Metallurgy, 2001, t. 37, nr 5, s. 29-35.
• 4. Igharo M., Wood J. V.: Effect on consolidation parameter on properties of sintered high speed steels. Powder Metallurgy, 1990, t. 33 nr 1. s. 70-76.
• 5. Leżański J.: Infiltracja cieczy w porowatych materiałach metalowych. Zesz. Nauk. AGH, Metalurgia i Odlewnictwo, Kraków 1988, nr 118.
• 6. Hoyle: High Speed Steels. Butterworth & Co. Publishers. Cambridge 1998.
• 7. Torralba J. M., Gordo E.: PM high speed steel matrix composites. State of the art. Powder Metallurgy Progress, 2002, t. 2, nr 1, s. 1-9.
• 8. Oliveira M. M.: High-speed steels and high-speed steels based composites. International Journal of Materials and Product Technology, 2000, t. 15, nr 3-5, s. 231-251.
• 9. Lou D., Hellman J., Luhulima D., Liimatainen J., Lindros V. K.: Interactions between tungsten carbide (WC) particulates and metal matrix in WC-reinforced composites. Materials Science and Engineering, 2003, A 340, s. 155-162.