Thermal cycling effect on a structure of multilayer composite material made of 08kp and 08Kh18N10 steels

The article researches the effect of five cycles of heating to a temperature of 1000 °C and two cycles of heating to a temperature of 1100 °C on the structure of a layered composite material consisted of 100 alternating layers of 08kp and 08Kh18N10 steels (one layer thickness is ~22 μm). As a result of the nickel and chromium diffusion during thermocycling, the thickness of the layers changed and an interlayer with a structure different from the structure of neighboring layers was formed. Heating to 1100 °C also has led to a partial disarrangement of the layered material structure. It was found that the real diffusion path of alloying elements during heat treatment significantly exceeds the calculated one, and chromium atoms are redistributed between the layers of the material much more actively than nickel atoms.

Chromium Diffusion Coating on an ODS Ferritic-Martensitic Steel and Its Oxidation Behavior in Air and Steam Environments

A chromium diffusion coating was applied on an oxide dispersion strengthened ferritic-martensitic (ODS-FM) steel to improve oxidation resistance at high temperature. By carrying out physical vapor deposition followed by inter-diffusion heat treatment, a thin Cr-rich carbide layer was produced on the ODS-FM steel. Both the as-received and surface-modified specimens were oxidation-tested at 650 °C in air and steam environments for 500 h. The surface-modified specimens showed improved oxidation resistance in both environments. In an air environment, both conditions exhibited a thin and continuous chromia layer, but the formation of Cr2O3 and (Mn, Cr)3O4 nodules resulted in greater weight gain for the as-received specimen. In a steam environment, weight gain increased for both the as-received and surface-modified specimen. Especially, the as-received specimen showed much greater weight gain with the formation of a thick oxide layer consisted of outer Fe-rich oxide and inner (Fe, Cr, Mn) oxide layers. On the other hand, a thin and continuous chromia layer was formed for the surface-modified specimen, which resulted in much less weight gain in a steam environment.

Polymer-induced metal diffusion during plastic processing: a reason for deposit formation

In the plastic-processing industry, the formation of unknown deposits at the interface between polymer melt and steel surfaces can pose major challenges, which occurs especially on screws, barrels, and tools. These deposits will detach during production and lead to quality restrictions mostly as spots in the products. We investigated the interactions between tool steel and polymer melt, especially polycarbonate, in the early stages of deposit formation. Steel-polymer-composite samples are prepared close to the realistic conditions in the plastic-processing industry. To get further insight, thin polymer films on tool steel specimens and its alloy elements, representing model systems, are prepared. X-ray-photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) are used to characterize the interfaces chemically. Additionally, atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used. We found iron and chromium diffusion into the polycarbonate melt induced by polymer metal interaction. Iron and polymer chains are immobilized at the interface by a chemical interaction, while chromium does not chemically interact with the polymer melt. Basing on these results, we propose a mechanism for deposit formation in plastic-processing machines and tools.