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LISKA, J., FILIPEK, J.: The resistance of ledeburitic tool steels against the abrasive wear. Acta univ. agric. et silvic. Mendel. Brun., 2012, LX, No. 6, pp. 231–242 The ledeburitic tool steels which used to be used mainly for cutting and shaping tools nowadays are frequently used for a manufacture of injection moulds, moulds for pressure castings of aluminium alloys and for moulds for ceramics processing. The article deals with fi ndings of ledeburitic tool steels resistance against abrasive wear. For the tests there were prepared the test samples of ledeburitic tool steels 19 436 and 19 573 (both according to CSN). Moreover there were prepared the samples from structural abrasion resistant material Hardox 450 and from unalloyed structural steel 11 373 (according to CSN). A wear resistance was examined by means of a laboratory test with an abrasive cloth and the Bond’s device. Herea er the article deals with a possibility of utilisation of ledeburitic alloyed steels for a manufacture of tools for a land processing. For the examination of a resistance against wear in land there was made a plough test in which the tested samples were mounted on plough blades. By means of both the laboratory and operational tests there was found multiple higher resistance against wear of ledeburitic tool steels rather than of structural steels. During a land processing there was found unsuitability of steels processed for a maximum hardness, which came out as fractures of several samples. abrasion, ledeburite, tool steel, test The enormous sum of money is invested into the repairs of abraded and worn parts every year. For example land contains a silica sand with the hardness 900-1280HV with strong abrasive eff ect (Suchanek et al., 2007). Discovering of right materials and their heat treatment for shelf life of parts in abrasive land environment is more and more important. For example the resistance against wear of low alloyed steel with a carbon content 0.55 %, so ly annealed and toughened rises 1.5 times and using quench hardening even 2.5 times (Filipek, Cerný, 2002). It is no less important to speak about an ecological benefi t of parts with higher abrasive resistance, longer lifetime and lower cutting resistance with regard to ecologically thinking times. It is known that blunt parts of a plough increase the energetic diffi culty during ploughing about 19% (Sedlak, Bauer, 1998). High alloyed ledeburitic tool steels are used for making of cutting instruments, moulding tools, compression moulds. These steels are also used for making of high pressure foundry moulds for aluminium castings and hammers and jaws for crushers. MATERIALS AND METHODS Test bodies For abrasive wearing test there were prepared test bodies. These bodies, with defi ned dimensions consisting (Fig. 1) of two tool materials 19 436 (according to CSN) or X210Cr12 (according to EN) and 19 573 (according to CSN) or X153CrMoV12 (according to EN), were prepared for the wear test. The other test bodies were made of the abrasiveresistance material Hardox 400 and for comparing they were made of the unalloyed structural steel 11 373 (according to CSN) or S235JRG1 (according to EN) with diff erent heat treatment (Tab. I). The samples were manufactured from the fl at steel 232 J. Liska, J. Filipek profi le with a grinding allowance a er the heat treatment. Heat treatment of ledeburitic steels The sample 19 436 – hardening machine Coderre. Heating in the protective atmosphere of a methanol and a nitrogen with carbon potential 0,8. The inclination and soak time are 60 minutes, only soak time 30 minutes at the temperature 940 °C. Cooling down in the oil at 80 °C. Tempering to the hardness 61 HRC, temperature 170 °C, soak time 45 minutes. The sample 19 573 – vacuum hardening machine Schmetz. The heating in the vacuum with three-degree inclination 650–850–1 060 °C, inclination and a soak time are 4 hours 30 minutes altogether (samples were quenched or tempered with big parts of moulds, the length of a soak time has to provide the heating of big parts. The sample was treated by nitrogen stream with the pressure 6 bar and the temperature of nitrogen 20 °C. Then the samples were tempered three times at temperatures 510, 530 and 480 °C. Test device The samples were tested on an abrasive cloth, in the Bond’s device and at an operational ploughing test. Wear test on the abrasive cloth according to CSN 01 5084 The instrument consists of a disc with new abrasive cloth for each test, abrasive material – corundum with granularity 120 and a clamping head. The test body is fastened in it and is pressed on 1: Test bodies for operational and laboratory tests I: Marking, heat treatment, hardness and chemical composition of test bodies Material according to CSN Heat treatment Average hardness [HV] Chemical composition (%)