An analytical review of the effect of high-temperature thermomechanical treatment on the structure and properties of steels as a possible effective method of strengthening the teeth of excavator buckets. It is shown that the application of this method can have a positive effect not only on the hardness, but also on the entire complex of their mechanical characteristics, such as plasticity, impact toughness and fatigue resistance. In relation to Hadfield steel as the most frequently used material of the bucket teeth, it is noted that with increasing deformation grade of billets from 1 to 5, tensile strength of steel increases from 570 to 1030 MPa, yield strength – from 480 to 790 MPa, relative elongation – from 14.3 to 17.9 %, relative contraction – from 17.2 to 20.1 %, impact strength KCU – from 1.51 to 2.14 MJ/m2. This article presents the results of metallographic analysis and comparative tests for abrasive wear of Hadfield steel samples after typical heat treatment practiced at bucket teeth manufacturers and thermomechanical treatment. It is established that high-temperature plastic deformation of steel samples before quenching increases their wear resistance by 1.7 times. The authors attribute the detected increase in wear resistance to the formation of fine martensite in the surface layers of steel with a needle size of 3-10 nm, which increases its hardness by 47%. It is concluded that the presence of fine martensite in the structure of Hadfield steel can increase the service life of excavator bucket teeth made of this material. The results of this study are planned to be used in the development of an improved technological process for manufacturing bucket teeth of excavators.

Based on the literature review, the authors arrive at the conclusion that abrasivity of rocks is not only governed by their strength, but also by the structure and parameters of mineral inclusions, such as shape, size and amount. In terms of the Khibiny’s apatite–nepheline ore of various kinds with different strength and mineralogical composition, it has experimentally been estimated using the modified Baron–Kuznetsov procedure how the strength of rocks affects the wear rate of specimens made of steel 110G13L that is most often used for manufacturing rapidly wearing parts of mining equipment. It is found that for all ore kinds tested, the steel wear rates are approximately the same irrespective of the ore strength. It has been supposed that on abrasion of steel on hard rock (f ~ 10) composed of grains of hard tabular nepheline with thin partings of relatively soft fine-grain apatite, nepheline grains disengage slowly, the contact surface becomes smooth and steel wear rate is reduced consequently. On the other hand, on abrasion on weak rock (f ~ 0.5) composed mostly of apatite, fast failure of this type rock causes continuous exposure of rough-surface apatite grains, which accelerates steel wear resistance. On stee

The extraction of oceanic ores will make it possible to extract a complex of strategic metals: manganese, nickel, copper, cobalt, molybdenum, zinc. The following materials are considered as cost-effective mineral raw in the ocean: manganese nodules – MN (Mn, Ni, Cu, Co), cobalt-rich manganese crusts – CMC (Co, Mn, Ni), deep-sea polymetallic sulfides – DPS (Cu, Zn, Au, Ag). As an example, the Indian concept of deepwater development is described, which proposes to use the pipeline as a transport of minerals from the bottom. The calculation of the pipeline transportation system with the indication of shortcomings is given. As an alternative, it is proposed to use a lift of a self-propelled device for minerals on a cable made of special material. The article presents a device for deep-sea mining of MN with pressure drop chambers. The method of application of this device for collecting CMC is replacing the pressure drop chambers with the clamshell type device. The grab must be made of strong and at the same time light material and can be equipped with a hydraulic hammer for preliminary destruction. Elements of the shock system of the hydraulic hammer must also be adapted to the conditions of deep-sea mining by using special metal alloys for manufacturing. The destroyed mass is temporarily stored in a hopper mounted on a collector, which can be made of nylon mesh stretched between plates of titanium alloys. The calculation of the performance of the device for deep-sea mining from is presented.