Zr+ ION BEAM SURFACE IRRADIATION FOR IMPROVING FATIGUE DURABILITY OF 12Cr1MoV AND 30CrMnSiNi2 STRUCTURAL STEELS

Abstract

A cyclic tension and alternating bending tests of 12Cr1MoV and 30CrMnSiNi2 steels specimens in as-supplied state and after surface nanostructuring by Zr+ ion beam have been carried out. Distinctions in formation of strain induced relief, as well as the cracking pattern of modified surface layer are illustrated by methods of optical microscopy and interferential profilometry. Changes to occur in subsurface layer are characterized by means of nanoindentation and fractography (scanning electron microscopy) of fracture surfaces. The description of differences of deformation behavior is carried out with use of the multilevel approach.

Structural Aspects of Zr⁺ Ion-Beam Surface Modification and Mechanical Properties of 12CrMoV Steel

“…Thus, the observed effects of mechanical properties changing under static and cyclic loading should be interpreted in terms of considering the loaded specimens as a multi-level systems: Zr ion-alloyed subsurface layer (with thickness of several µm) and temperature induced "softened" layer (up to 100-120 µm) -strengthened due to thermal cyclic of the bulk material. The behavior of this multilevel system should illustrate the benefit under cyclic loading, as was found in our previous studies [4,12].…”

“…Recently the technique for metal ions irradiation to modify subsurface layer of structural materials that is accompanied by certain heating during the processing and formation of new chemical Zr-based phases were developed in ISPMS SB RAS. The formation of the modified surface layer gives rise to decreasing its hardness, but substantial increases of the fatigue durability [4]. The purpose of this work is to analyze the structure and estimate the changes of mechanical properties of structural 12CrMoV steel after the treatment.…”