Intermetallic phase kinetic formation and thermal crack development in galvanized DCI

Abstract

A new class of material characterized by mechanical properties close to the traditional low and medium carbon steel is the Ductile Cast Irons (DCIs). High castability and low production costs allow them to be used in many fields, ranging from automotive to piping. In this class of iron-based alloy the content of carbon is mainly localized in the graphite nodules, which are dispersed in a metallic matrix characterized by different phases: ferrite, austenite, pearlite, martensite or their mix, depending on the chemical composition and the heat treatment. Metallic matrix is subjected to the corrosion phenomenon, and, for this reason, the study and the development of traditional and innovative protection techniques are important, mainly in critical applications. Hot dip galvanizing is one of the investigated protections because the zinc is able to protect the iron-based alloys thanks to the reduction potential that is lower than the iron one. In this work, a ferritic-pearlitic DCI (GS500) is galvanized by using a pure Zn bath at 440°C in order to generate a zinc coating at different dipping time. The presence of thermal cracks is observed by means of a Scanning Electron Microscope (SEM).

Intermetallic Compounds Formation during 316L Stainless Steel Reaction with Al-Zn-Si Coating Alloy

“…Moreover, the cracked IMC layers will detach from the substrate and fall down in the coating pot. Such interlayer cracks have also been reported earlier [22]. Ultimately, this event shall also contribute to the bottom dross formation in the coating pot.…”

The Zinc-Rich Corner of the Fe-Si-Sn-Zn Quaternary System at 450 °C

“…Hot dip galvanizing is one of the most versatile anti-corrosion technologies of steel [1][2][3][4][5], for which Zn and its alloys are mainly used amongst various materials. Since the galvanized coating is easily interfered by Si in steels, its anti-corrosion effect is greatly reduced.…”