Influence of Thermomechanical Treatment Modes on Wear Resistance of Mining Equipment Material

Abstract

This work presents results of experimental researches of influence of various high-temperature thermomechanical treatment (HTMT) modes in 35KhGSA steel – material applied in rock-destroying cutters – on hardness and wear rate for the most common abrasive rock in mining operations – sandstone. It has been found out that HTMT leads to increase of steel hardness and reduction of wear rate compared to heat treatment applied at manufacture of cutters. The maximal increase of hardness (by 23%) and reduction of wear rate (by 38%) corresponds to the mode of distortion accumulation of ~1,5 at 900 °С at water quenching and tempering at 230 °C. A conclusion that thermomechanical treatment is an effective way to increase the wear resistance of steels applied in the conditions of abrasion wear has been drawn.

Study of the Geo-Ecological State of Groundwater of Metropolitan Areas under the Conditions of Intensive Contamination Thereof

“…The pH varies from 7 to 7.5; however, in the areas of swamps frequently does not exceed 6.8. It is worth noting that within the developed part of the district, due to intensive contamination, the mineralization value can reach 3 g/dm 3 . Moreover, active contamination by organic compounds results to the formation of reducing conditions (Eh<0 mV), which facilitate the migration of heavy metals, as well as the accumulation of toxic substances [6,18].…”

“…The pH value varies from 7 to 7.6; in the areas of swamp deposits it does not exceed 6.7. Due to the intensity of contamination, the value of mineralization can increase to 3.5 g/dm 3 .…”

“…The underground water of site 1 also contains an increased amount of sulfates, reaching 468.3-560.5 mg/dm 3 , the presence of which in some cases may be associated with the discharge of industrial wastewater and household waste into the Okhta river, flowing 125-130 m from the construction site. The groundwater of site 2 also contains a significant content of chlorine ion, the values of which vary from 215.6 to 244.7 mg/dm 3 . Infiltration of sulfates and chlorides can take place due to constant leaks from the old sewage system, the replacement of which, within the district territory, is supposed to be implemented before 2025.…”

“…It should be understood that studying the hydro-chemical mode of groundwater allows assessing the changes in the intensity of the manmade impact and in the composition of the introduced components [3,17]. The groundwater horizon, to a greater extent, serves as an indicator of specific features and pattern of the territory contamination due to the absence of an overlapping water confining stratum and to the presence of a direct connection with precipitation, leaks, surface watercourses and water bodies [9,13].…”

New Opportunities for the Digital Economy: the Implementation of an Effective State Innovation Policy

“…According to the Rosstat, only a few percent of those employed in the economy, worked in the profession related to information and communication technologies, 36% of which are under the age of 30. For example, in Germany, about 10% of the population is employed in high-tech industries (10)(11)(12)(13)(14)(15)(16). Nevertheless, the share of the digital economy in the country's GDP in recent years grew to 1.8 trillion rubles and reached 2.22%.…”