The paper presents the results of comparative tests of the fatigue properties conducted on two non-ferrous alloys designated as Al 6082 and

Al 7075 which, due to the satisfactory functional characteristics, are widely used as engineering materials. The fatigue tests were carried

out using a proprietary, modified low cycle test (MLCF). Particular attention was paid to the fatigue strength exponent b and fatigue

ductility exponent c. Based on the tests carried out, the results comprised within the range defined by the literature were obtained. These

results prove a satisfactory sensitivity of the method applied, its efficiency, the possibility of conducting tests in a fully economical way

and above all the reliability of the obtained results of the measurements. Thus, the thesis has been justified that the modified low cycle

fatigue test (MLCF) can be recommended as a tool used in the development of alloy characteristics within the range of low-cycle variable

loads

In this study, the mechanical tests were carried out on ductile iron of EN-GJS-600-3 grade and on grey cast iron of EN-GJL-250 grade. The fatigue life was evaluated in a modified low-cycle fatigue test (MLCF), which enables the determination of parameters resulting from the Manson-Coffin-Morrow relationship. The qualitative and quantitative metallographic studies conducted by light microscopy on selected samples of ductile iron with spheroidal graphite and grey cast iron with lamellar graphite (showing only small variations in mechanical properties,) confirmed also small variations in the geometrical parameters of graphite related with its content and morphological features.

One of the techniques commonly applied today for deep foundation construction is based on self-drilling injection micropiles. Micropiles are structural elements intended primarily for reinforcing foundations and buildings, particularly under difficult terrain conditions. The goal of the tests presented herein is to inspect the fatigue resistance, strength and ductility of injection micropiles formed from 28Mn6 steel at loads significantly exceeding the values defined for the fatigue test in the requirements of the relevant European Assessment Document (EAD). The test results and the micropile bar strain model εM presented in this paper are primarily of interest to designers for the purposes of determining the fatigue resistance of steel micropiles, which find particular application in land degraded by mining activity that is characterised by frequent terrain vibration and mining-induced tremors. None of the R25N injection micropile bars failed during the fatigue resistance testing at 2·10⁶ cycles at a load F_u = 0.7·F_Re0.2 (under the yield strength of the 28Mn6 steel) as well as at F_u = 1.0·F_Re0.2 and F_u = 1.2·F_Re0.2, where the bars operated at the limit of and significantly above the load F_Re0.2 which results in stress at the yield point of the 28Mn6 steel. Furthermore, the bar tests conducted at static and cyclic loading demonstrated the high strength and good ductility of the 28Mn6 steel.