The paper presents the study of internal defects resulting from the continuous casting of steels. The 50 samples were taken from a total of 20 continuously cast bits of different steel grades. The investigation of the causes of internal defects, shown on the analyzed samples, started from the assumption that the secondary metallurgy was performed correctly. The following internal defects have been evident: internal cracks (axial cracks, section cracks), central porosity and marginal punctuation impurities.

Due to the good properties related to wear resistance and vibration absorption capacity, the polymeric materials successfully replace the metallic materials. These are used in the production of sliding motion couples. Rubbing couples whose materials are polymer / steel based are of particular interest for technical use. In order to operate any mechanical system with sliding motion at optimum parameters, the indication of tribological characteristics for the materials of the frictional coupling is a convenient means of characterizing faster the tribological behavior, when the working conditions are modified. In this paper it is analyzed by the help of an experimental study, the factors affecting the wear of a coupling of polymer material/steel. Materials subjected to tribological analysis are polymeric materials, such as polyamide (PA) and polytetrafluoroethylene (PTFE) in contact with a metallic material (steel). The connection between the friction coefficient and the operating parameters (load, speed) and the rate of wear of these materials under experimental conditions will be established. Testing of the two materials was made on a pine stand on disc. The tribological tests were performed varying load and speed for a given length of friction, traveled pine. The wear of the two materials tested for the experimental conditions was measured. The experimental researches were carried out in dry friction conditions.

Knowing how to deform the Turcite thermoplastic material under the action of conical penetrators is a means of obtaining information on the processing of the counterpart (made from a metal material with higher hardness) with which it comes into contact.The paper aims to theoretically determine the depth of penetration of the thermoplastic material under the action of some conical penetrators and to establish the coefficient of static and kinetic friction under the action of these penetrators. The proposed model will be validated experimentally on a tribological stand made for this purpose.

This paper presents the results of laboratory research on the influence of heat treatment on the corrosion resistance of austenitic steels (Cr-Ni, Cr, Mn, Cr-Mn-Ni), research that may extend under certain conditions and ferrites steels and semi-ferrites chrome steels.This type of intercrystalline corrosion was observed in other alloy systems due to media containing chloride ions.The experimental results consist in comparing structural changes and corrosion rate for different types of austenitic steels that were made experimental research.

Aim of the study is to present the technological process of obtaining cast iron with lamellar graphite for use in the manufacture of cylinder liners, and to identify the main alloying elements and track their influence on the mechanical properties of cast iron with lamellar graphite. Also paper presents analysis of 20 batches of cast iron with lamellar graphite, which are made of cylinder liners, in terms of chemical composition and the mechanical properties. After the analysis of the 20 castings of cast iron Fc 250 it is observed that: the increase in the carbon content shows a decrease of the tensile strength and hardness of the gray cast iron; the increase in silicon content shows a decrease in hardness and tensile strength. Decreasing the amount of graphite and especially the alloy of silicon iron lead to hardness increase 1% Si increases hardness by 50 HB). A statistical analysis has been performed on the data obtained that accounts for changes in alloying additions. A modeling and optimization of mechanical properties (tensile strength and hardness) was performed according to the percentages of carbon, silicon and manganese. Mathematical modeling found that the hardness and traction resistance of the cast iron decreased with the increase in carbon, silicon and manganese content.