An Assessment of the Applicability of Austempered Ductile Iron Containing Mo and Ni for Mining Machines Parts

Abstract

The research described in this article is a fragment in the series of published works trying to determine the applicability of new materials for parts of the mining machinery. Tests were carried out on the -very popular in mining applications -36HMN steel and three types of the austempered ductile iron, using special stand for the controlled abrasion testing of samples subjected to the effect of loose abrasive. Tests carried out with the use of corundum showed the competitive properties of cast iron as compared with the examined steel. Microscopic evaluation, hardness measurements and magnetic tests showed that the surface layer of austempered ductile iron undergoes a strong work hardening, resulting in abrasion wear indices superior to those of the steel for heavy-duty use.Keywords: austempered ductile iron, wear resistance, microstructural transformactions Badania przestawione w artykule wpisują się w cykl publikacji określających przydatność nowych materiałów na części maszyn górniczych. Testy przeprowadzono dla popularnej w zastosowaniach górniczych -stali 36HMN i trzech rodzajów żeliwa sferoidalnego ausferrytycznego, na specjalnym stanowisku do kontrolowanego ścierania próbek suchym ścierniwem. Badania zrealizowane z użyciem korundu wykazały konkurencyjne właściwości żeliwa w stosunku do badanej stali. Ocena mikroskopowa oraz pomiary twardości i magnetyczne wykazały, że w warstwie wierzchniej żeliwa sferoidalnego ausferrytycznego zachodzi silne umocnienie spowodowane zgniotem, co skutkuje lepszymi niż dla stali wskaźnikami zużycia dla dużych obciążeń.

Abrasive Wear Properties of Fe-Based Alloys Designed for Mining Applications

“…The reason of a high wear resistance is most likely the transition of austenite into martensite occurring in the surface layer under a load. The authors analysed the problem of the phase transitions occurring in cast irons containing Ni and Cu in their earlier study [9]. They found, inter alia, a distinct correlation between the content of metastable austenite and an increase in the surface hardness.…”

“…A number of authors, including Schissler et al [5], Owhadi et al [6], Hayrynen et al [7,8], Myszka and Wieczorek [9,10] confirmed a beneficial influence of the strain-induced transition on the wear properties of ADIs.…”

Comparative Studies on the Wear of ADI Alloy Cast Irons as Well as Selected Steels and Surface-Hardened Alloy Cast Steels in the Presence of Abrasive

“…They substantiated this fact by a low resistance of graphite to microcutting and by propagation of microcracks from spots formed after the destruction of the graphite nodules. Myszka and Wieczorek [11] performed wear tests for 34CrNiMo6 hardened steel and three types of austempered ductile iron containing Mo and Ni. Wear tests showed that the cast iron had properties comparable to those of the steel tested and that the wear resistance of ADI was increasing along with an increase in the nominal load.…”

“…Schissler et al [15] and Owhadi et al [16] found that a low content of martensite in the microstructure (at a level of 0.1%), which had been formed as a result of the austenite transformation, had a positive impact on wear properties of cast irons. Myszka and Wieczorek [17] after having performed wear tests of three types of nodular cast iron with addition of Cu and Ni in corundum abrasive have found that the hardest cast iron has the best wear resistance, but strengthening of the surface apparently occurs in the material with the lowest hardness and best ductility that contained the highest amount of retained austenite.…”

“…After the machining, the chain wheels made of nodular cast iron were subjected to isothermal treatment. The parameters of the austempering and isothermal quenching processes were selected on the basis of previously conducted studies [11,17,20]. The list of the process parameters is shown in Table 4, while mechanical properties in Table 5.…”