The Influence of Corrosion Attack on Grey Cast Iron Brittle-Fracture Behaviour and its Impact on the Material Life Cycle

Abstract

The paper is concerned with brittle-fracture behaviour of grey cast iron attacked by corrosion and its impact on the life cycle of a spare part made of grey cast iron. In a corrosion chamber, outdoor climatic conditions (temperature and relative air humidity) were simulated in which degradation processes, induced by material corrosion, degrading mechanical properties of a material and possibly leading to irreversible damage of a machine component, occur in the material of maintenance vehicles that are out of operation for the period of one year. The corrosion degradation of grey cast iron, which the spare parts constituting functional parts of an engine are made of grey cast iron, is described with regard to brittle-fracture behaviour of the material. For the description of corrosion impact on grey cast iron, an instrumented impact test was employed. A corrosion degradation effect on grey cast iron was identified based on measured values of total energy, macro plastic deformation limit, initiation force of unstable crack propagation and force exerted on unstable crack arrest. In the first part of the experiment, a corrosion test of the material concerned was simulated in a condensation chamber; in the second part of the experiment, research results are provided for the measured quantities describing the material brittle-fracture behaviour; this part is supplemented with a table of results and figures showing the changes in the values of the measured quantities in relation to test temperatures. In the discussion part, the influence of corrosion on the values of unstable crack initiation and arrest forces is interpreted. In the conclusion, an overview of the most significant research findings concerning the impact of corrosion on the life cycle of grey cast iron material is provided.

Simulating the Climatic Impact on Vehicle Engine Function Parts

“…We can assume that corrosion spreads in the bulk of the material and can cause material degradation which may reach to a limit state that leads to irreversible damage in the life cycle of the material causing considerable damage to state property. (1,3) These findings have been demonstrated by the authors publications (10). The samples that have been protected by the MilCorr VpCI Shrink Film throughout the experiment have not been affected by corrosion and it can be said that the film is suitable for outdoor application for 5 years.…”

“…It can be deduced from the graph that the corrosion degradation effect contributes considerably to the occurrence and the course of the examined parameter (KCV) of the machine part, the engine cylinder inserts, thereby reducing the utility of the machine component and resulting in the use of unplanned financial means for repair. The corrosion protection applied on the samples using the MilCorr VpCI 126 White foil is suitable for outdoor storage of the vehicle TATRA 815 6x6 VVN (1), ( 2), (3). The influence of corrosive effects in relation to ambient temperature and simulated 18 cycles in Figure 2, which can be interpreted as the effect of climatic changes (ambient and relative humidity) for about 3 years, can be identified from the temperature of -20 °C, which is possible in the territory of the Czech Republic.…”

“…Samples that have been protected by the MilCorr VpCI Shrink Film over the entire experimental period have not been affected by corrosion and it can be said that the film is suitable for outdoor application for 3 years. (1,3) The test set C (Figure 1c) was tested in the condensation chamber for 27 cycles. The test bodies exhibit visible extensive corrosion attacks characterized by a relatively visible layer of corrosion products and corrosion islands forming a coherent layer with a varying thickness of corrosion products.…”

“…The samples that have been protected by the MilCorr VpCI Shrink Film throughout the experiment have not been affected by corrosion and it can be said that the film is suitable for outdoor application for 5 years. (1,3) ECS Transactions, 105 (1) 531-539 (2021)…”

Failure mechanism in the pearlite structure with lamellar graphite due to temperature

“…In the base phase of fine pearlite there is lamellar graphite, on which it can be assumed that the field of elastic deformations with a high density of deformation energy is concentrated and thus the conditions for brittle fracture are created. Grey cast iron is a very brittle material and may contain many cast defects [5]. Both facts lead to a wide distribution of the mechanical test results that require statistical processing.…”