HIGH TEMPERATURE CORROSION OF THIN SHEET STEEL 08KP IN AIR

The study of the nature of high-temperature corrosion of metals is one of the tasks in substantiating the relevance of the use of corrosion-resistant, heat-resistant coatings and barrier layers obtained on the basis of the natural oxidation process. The article presents the gradation of oxidation of surfaces of 08kp thin-sheet steel at diff erent temperature-time parameters of one cycle “heating-cooling”. To regulate the processing modes and register thermal eff ects, a diff erential thermal analysis device was used. It is shown that the eff ect of elevated temperatures on steel in air at atmospheric pressure triggers an intensive growth of scale, which peels off from the metal base and breaks down. After descaling on the steel surface, in addition to blue tarnishing, in some cases, fi lms of a red tint were found. Based on the data of diff erential thermal analysis, an att empt was made to separate and interpret transformations related directly to steel and to reactions in scale associated with iron oxides.

Modeling thin-walled elements with regard to steel hardening

Today in Russia 13% of buildings are built on the basis of a metal frame. To increase the energy efficiency of the industry, the use of thin-walled steel structures is one of the most technologically advanced and efficient solutions. To ensure the bearing capacity and reduce the risks of failure of buildings and structures at the design stage, it is important to correctly assess the reliability of the system, taking into account all influencing factors. The technology for the production of thin-walled profiles determines the factors that affect their stress-strain state. Uneven distribution of mechanical properties over the cross-section of the profile: hardening in the bending corners and adjacent zones leads to an increase in the strength of the metal. The article presents the results of numerical modeling of samples from thin sheet steel with and without the effect of hardening. The object of research is a thin-walled sigma profile with a section height of 300 mm, an element length of 4500 mm, operating under compression with bending. Metal hardening values are based on experimental data obtained by the authors. The stresses and displacements obtained as a result of the simulation were analyzed in four sections along the profile length: at a distance of 0.5 m, 2.3 m, 3.0 m and 4.0 m from the support. It is concluded that the supercritical work of the element without hardening of the material occurs earlier than in the element with hardening. The maximum stresses in the element without hardening exceed the stresses in the element with hardening by more than 30%. The maximum displacements in hardening are more than three times.

Laser Treatment for Strengthening of Thin Sheet Steel

This paper presents the results of computer simulations and experimental studies, aiming to increase the mechanical strength of sheet metal parts manufactured from high-quality structural carbon steel by means of local laser processing. The effects of laser processing on the strength of steel sheet plates and their ability to resist bend load after laser treatment were studied. The results of bending experiments and computer simulations of elastoplastic deformation establish that local laser processing with surface melting can be used to increase the mechanical strength of structural elements made from thin sheet steel C22E and to decrease its deflection under similar workload, as an alternative to the application of complex geometric shapes, additional strengthening elements, or heat treatment.