Browsing by Subject "cynkowanie"

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Kształtowanie powłoki cynkowej na odlewach z żeliwa sferoidalnego
(Data obrony: 2012) Szczęsny, Andrzej
Wydział Odlewnictwa
Hot-dip galvanising is one of the most popular and effective methods of protection of iron and iron-carbon alloys from the destructive effect of corrosion. Though technical literature gives comprehensive description of the hot dip galvanising process of iron and structural (low $Si$ content) steel products, not much attention has been devoted to the process of galvanising cast iron and the kinetics of protective coating growth on the surface of iron castings, while the work that has been done does not cover the whole problem connected with silicon content in cast iron much higher than in steel, and to the presence of graphite precipitates in the structure of the cast iron metallic matrix The additional problem is quality of the surface layer of casting , i.e. an outer layer of the cast material which has changed its physical and sometimes also chemical properties respective of the core material properties. Therefore, studies were carried out to trace an impact of the nodular graphite precipitates, of the content of the metal matrix phases (ferrite and pearlite) and of the surface roughness Ra on the kinetics of the coating growth. To better grasp the kinetics of the zinc coating growth, rapid cooling treatment - "freezing" of the samples was applied. The investigations described in the present study have been completed with a definiton of the mechanism of the zinc coating growth on the surface of ductile iron casting, based on the concept of a peritectic crystallization in an $Fe-Zn$ phase system in the alloyed layer of zinc coating.
Access status: Open Access ,
The influence of microstructure of 30MnB4 steel on hydrogen-assisted cracking
(2015) Krawczyk, Janusz Ryszard; Bała, Piotr; Tokarski, Tomasz; Pawłowski, Bogdan; Frocisz, Łukasz
This paper analyzes the problem of susceptibility to hydrogen-assisted cracking (fracture behavior) of zinc-coated screws made of 30MnB4 steel. Two samples (screws) were compared after proper and improper heat treatment affecting hydrogen solubility during the further galvanic process and resulting in different fracture modes. Both samples were loaded to failure by torsion. The fracture surface and microstructure of the samples were examined using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).