Influence of plasma electrolytic hardening modes on the structure and properties of 65G steel

This work presented a study of the structure, hardness and wear resistance of 65G steel treated with electrolyte-plasma hardening under different conditions. The electrolyte-plasma hardening technology and a laboratory installation for the realisation of electrolyte-plasma hardening are also described. After electrolyte-plasma hardening, we have established that a modified layer consists of the a-phase (martensite) and M3C cementite. The study results showed that electrolyte-plasma hardening makes it possible to obtain layers on the 65G steel surface that provides an increase in microhardness by 2.6 times, wear resistance by two times, resistance to abrasive wear by 1.7 times compared to the original samples. In addition, local hardening ensures the achievement of technical and economic effects due to the absence of the need to isolate an unwanted site of parts, processing only the areas requiring hardening.

IMPROVING THE SURFACE STRUCTURE OF MASSIVE PARTS BY THE PLASMA METHOD

An increase in the reliability of the operation of large-sized and massive parts by plasma hardening of their surfaces is substantiated. It has been established that the formation of several structural zones of different microhardness is observed in detail along the depth of hardening, indicating the formation of a gradient-layered structure. It has been proved that at ultrafast heating rates, which occur during surface plasma hardening, phase and structural changes move to the high temperature region, changing the kinetics of the appearance and growth of new phase nuclei. In this case, fine-grained austenite is formed, which is transformed into a highly dispersed martensitic structure, which increases the strength and reliability of the surfaces of the parts.

The technology of thermal cyclic electrolytic plasma hardening of steels

This work describes the technology of thermal cyclic electrolytic plasma hardening, as well as describes the design features of the electrolytic plasma heater. There are presented the results of the research of medium-carbon steel hardness treated by thermal cyclic electrolytic plasma hardening under different conditions. An industrial installation for thermal cyclic electrolytic plasma hardening of materials was developed to carry out thermal cyclic electrolytic plasma hardening of steels in an automated mode. Tempered layers were obtained on the surface of the samples with average thickness values from 0.5 to 10 mm and hardness up to 750 HV. Experimentally that the alternation of switching on the electric potential at a voltage of U1 = 320 V and U2 = 200 V provides heating of the product surface to a depth of 10 mm. In this case, the maximum hardness of the surface layer (750 HV) practically does not depend on the thickness of the hardened layer. The hardness of the hardened layer of the product gradually decreases from the maximum (750 HV) to the hardness of the base (280-300 HV). The developed installation allows to vary the electrophysical parameters within a wide range: to set the voltage, the duration of processing, the time of switching on and off the voltage.

Research of the fracture of "75ХМ" steel during plasma hardening

The reasons for the abnormal destruction of steel 75ХМ during plasma hardening are studied. The results of microstudies and recommendations for the prevention of these destructions are presented. Keywords: steel, plasma hardening, microstructure, microhardness. trekinHYPERLINK, [email protected]

Renovation features of powder high-speed steels broaches with plazma hardening

The comparative studies results of the durability of cutting properties of new and restored by regrinding and repeated plasma hardening with the application of multi-layer Si—O—C—N nanocoating system (PECVD by cold atmospheric plasma) powder high — speed steels broaches teeth for the processing of hard-to-process materials profilecomposite gas-turbine engines components are presented.