In the last years the attention to environmental topics leads a new approach solution in classical protection techniques, introducing innovative way oriented to optimize different coating properties. Hot-dip galvanizing is a classical processing to generate coatings on iron-based surfaces, used unchanged since 200 years, but many components used in the bath, for examples Pb, are dangerous for human health. Presence of Pb in the bath is important for fluidizing properties, sometimes replaced by Sn. In this work damage and crack propagation in intermetallic phases of zinc based coatings were investigated in order to evaluate dipping time and chemical influence of Sn and Ti in the bath, comparing not-alloyed zinc bath. Hot dip zinc coated ipersandelin steel specimens were investigated in order to identify the main damaging micromechanisms during bending tests, considering both chemical composition and intermetallic phases distribution influences. Longitudinal sections of bended specimens were observed by means of a LOM (Light Optical Microscope) and main damage micromechanisms were identified as longitudinal and radial cracks. Experimental results obtained with Zn-Sn and Zn-Ti baths were compared with coatings obtained using Zn bath.
Influence of dipping time on cracking during bending galvanized coatings with different Sn and Ti contents
DI COCCO, Vittorio;
2010-01-01
Abstract
In the last years the attention to environmental topics leads a new approach solution in classical protection techniques, introducing innovative way oriented to optimize different coating properties. Hot-dip galvanizing is a classical processing to generate coatings on iron-based surfaces, used unchanged since 200 years, but many components used in the bath, for examples Pb, are dangerous for human health. Presence of Pb in the bath is important for fluidizing properties, sometimes replaced by Sn. In this work damage and crack propagation in intermetallic phases of zinc based coatings were investigated in order to evaluate dipping time and chemical influence of Sn and Ti in the bath, comparing not-alloyed zinc bath. Hot dip zinc coated ipersandelin steel specimens were investigated in order to identify the main damaging micromechanisms during bending tests, considering both chemical composition and intermetallic phases distribution influences. Longitudinal sections of bended specimens were observed by means of a LOM (Light Optical Microscope) and main damage micromechanisms were identified as longitudinal and radial cracks. Experimental results obtained with Zn-Sn and Zn-Ti baths were compared with coatings obtained using Zn bath.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
