Forecasting the Corrosion Fatigue Life of Structural Materials in Chemical Engineering
Authors: Vasilyevich Pachurin German , Aleksandrovich Kuzmin Nikolay , Vadimovna Mochalina Mariia , Aleksandrovich Filippov Alexey , Venediktovna Smirnova Zhanna 
Published: August 2024

Introduction:
The most important task in the development of modern chemical engineering
is to improve the quality of metal products and parts made from them, increase their
efficiency, reliability, and fatigue life, bring these indicators to the level of world standards, and
ensure the competitiveness of domestic products in the foreign market. The structural safety of
chemical engineering equipment is largely determined by the operational reliability of its component
elements. The most common and progressive way of their manufacture is cold pressing
methods, the quality and reliability of which are largely defined by the condition of the gauged
bars' surface. At the same time, the performance characteristics of machinery parts and mechanisms
are determined mainly by the properties of the surface layers of metal, since all destruction
processes, especially during cyclic loading, usually start from the surface and depend on its
structure and physical and chemical status. The role of the type of metal surface imperfection
increases greatly with corrosion fatigue, which is determined by the formation of protective barrier
films. In the absence of stress, these films reduce the rate of corrosion, and during cyclic
loading, they are continuously destroyed. In addition, a stress concentration appears that is
caused by surface damage, leading to the formation of corrosive cavities on it. In this paper,
based on theoretical research, a physical parameter is proposed that controls the corrosion fatigue
life of strain-hardened structural materials of chemical engineering, serving as an indicator
of the degree of strain hardening under static tension. An analysis of experimental data has confirmed
that the technological plastic processing of structural materials, leading to a decrease in
the value of this indicator, causes an increase in their resistance to corrosion-fatigue failure.

Purpose:
The purpose of this work was to identify a physical parameter that controls the corrosion
fatigue life of technologically processed structural materials of chemical engineering.

Methods:
The experimental test procedure included mechanical tests under static and cyclic
loading. Structural materials widely used in chemical engineering, prestrained at different degrees,
were selected for the study. Static tension tests of standard samples were carried out on
ZD 10/90 and UME-10TM machines with a strain rate of 2 × 10-3 sec–1. The samples were loaded
at a frequency of 50 Hz using the MIP-8 machine. A widely spread 3% aqueous solution of
sea salt was used for testing in a corrosive environment.

Results:
It has been established that a physical parameter that controls the corrosion fatigue life
of materials is the exponent in the equation of the strain hardening curve under static tension. It
has been shown that the process of plastic treatment of material, leading to a decrease in its size,
causes an increase in its resistance to corrosion-fatigue failure.

Conclusion:
It has been shown that in order to assess the feasibility of a particular process
treatment in order to increase the resistance to corrosion fatigue of structural materials, it is necessary
to trace its impact on the value of the strain hardening index under static tension.