Effect of Filter Coating on the Quasi‐Static and Cyclic Mechanical Properties of a G42CrMo4 Casting

Abstract

In this paper, the effect of a mullite coating on a carbon-bonded alumina filter used in steel melt filtration on the mechanical properties of the cast steel G42CrMo4 (1.7231) at both quasi-static and cyclic loading is presented. The investigations cover quasi-static tensile tests at different temperatures. Additionally, cyclic tests in high-cycle fatigue (HCF) and very high-cycle fatigue (VHCF) regimes were performed. Fracture surfaces as well as cross-sections are examined by scanning electron microscopy and light microscopy to determine the non-metallic inclusions responsible for failure. In comparison to the uncoated filter, a mullite coating on the filter leads to a deterioration of deformation characteristics and fatigue lifetime of the cast steel. This effect is attributed to a higher amount of large non-metallic inclusions, which were not retained by the coated metal melt filter.

Microstructure of Non‐Metallic Inclusions Identified in Cast Steel 42CrMo4 after Metal Melt Filtration by Novel Foam Filters

“…These small endogenous inclusions tend to form clusters. According to ref., two inclusions with a distance ≤30 μm belongs to the same cluster. These clusters of small endogenous inclusions were the reason for the fatigue failure in the VHCF regime …”

“…Details of the manufacturing process of these different filter variants and their functionality are given in ref . In order to investigate the impact of the entrapment capability of the novel developed metal melt filters, the mechanical behavior of specimens prepared out of the as‐cast material after application of several filter variants was investigated, too . In particular, the fatigue lifetime is very sensitive to the occurrence of non‐metallic inclusions within the tested specimen volume.…”

Influence of the Chemistry of Surface Functionalized Ceramic Foam Filters on the Filtration of Alumina Inclusions in Steel Melts

“…With regard to the mechanical properties of the filtered steel, Henschel et al [22] have certified the current filtration results concerning mullite coated as well as uncoated Al 2 O 3 -C filters. It is assumed that due to a mixed crystal system in case of mullite, the filtration of alumina inclusions is decreased, although it exhibits a higher amount of Al 2 O 3 compared to the Al 2 O 3 -C filter system.…”

Modelling of Crack Initiation in a G42CrMo4 Steel With Non‐Metallic Inclusions

“…Preliminary tests revealed no anisotropy effects. Some of the data have been published previously, and methodical aspects are also described in that paper. Additionally, the true stress–strain curves were described by the approximations and in order to obtain input data for modeling of the toughness behavior (see Table ).…”