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  • Author: Tomasz Lipiński x
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Abstract

Silumins are one of the most popular group among aluminum casting alloys. They are characterized by good mechanical and casting properties, low density, good electric and thermal conductivity, a low degree of contraction, good corrosion resistance and a relatively low melting temperature.

The mechanical properties of hypoeutectic silumins can be improved through chemical modification as well as traditional or technological processing. Modification improves the mechanical properties of alloys through grain refinement. The effect of treatment has been given a lot of information first of all about microstructure and mechanical properties. This study presents the results of treatment of an Al-7%SiMg alloy with composition CuAl10Fe3Mn2 (as a powder) + (Al-7%SiMg + CuAl10Fe3Mn2) (as a powder) + (Al-7%SiMg + CuAl10Fe3Mn2) (in the form of a rod) in three different ranges. The experiments were conducted following a factor design 23 for 3 independent variables. The main addition was aluminum bronze, as well as clear or melted with raw alloy. The influence of the analyzed modifiers on the microstructure and mechanical properties of the processed alloy was presented in graphs. The modification of a hypoeutectic Al-7%SiMg alloy improved the alloy’s properties. The results of the tests indicate that the mechanical properties of the modified alloy are determined by the components introduced to the alloy.

Abstract

The article discusses the results of a study investigating the effect of the number of fine non-metallic inclusions (up to 2 μm in size) on the fatigue strength of structural steel during rotary bending. The study was performed on 7 heats produced in an industrial plant. Fourteen heats were produced in a 100 ton oxygen converter. All heats were subjected to vacuum circulation degassing.

Steel sections with a diameter of 18 mm were hardened and tempered at a temperature of 200, 300, 400, 500 and 600°C. The experimental variants were compared in view of the applied melting technology and heat treatment options. The heat treatments were selected to produce heats with different microstructure of steel, from hard microstructure of tempered martensite, through sorbitol to the ductile microstructure of spheroidite. The results were presented graphically, and the fatigue strength of steel with a varied share of non-metallic inclusions was determined during rotary bending. The results revealed that fatigue strength is determined by the relative volume of fine non-metallic inclusions and tempering temperature.

Abstract

Austenitic stainless steels are often used for a materials in the construction of machines and equipment for agricultural and for industrial construction. One of the most important factors constructional material is corrosion resistance. Equipment with austenitic stainless steel can be easy join by quickly welding at a not to high construction price, but one with the serious problem in aggressive environment is their corrosion resistance.

A few corrosion processes in crevices and awkward corners can be avoided at the design stage (low roughness parameters, round-section and other). But still the construction material is exposed to corrosion. These steels often come into contact with an aggressive environment based on nitric acid.

The main aim of this research is to investigate corrosion resistance in different time (48, 96, 144, 192, 240, 288, 336 hours). For this used weight loss of test samples and its profile roughness. The research was conducted on austenitic stainless steel in grade in Nitrate acid at 333 K.

Corrosion tests confirmed that the research this steel in 65% nitrate acid as a corrosive environments is characterized through proportionate to time corrosion process whose measure may be surface roughness. In industrial practice roughness parameters for all the research times can be used for determine the stage and size of steel corrosion.

Abstract

The parameters of high-grade steel are influenced by a combination of factors, including chemical composition and production technology. The impurity content is also a key determinant of the quality of high-grade steel. Inclusions may also play an important role, subject to their type and shape. Inclusions may increase the strength of steel by inhibiting the development of micro-cracks. The analyzed material was one grade of medium-carbon structural steel. The study was performed on 6 heats produced in an industrial plant in 140 ton electric furnaces. The experimental variants were compared in view of the five heat treatment options. The results were presented to account for the correlations between the fatigue strength coefficient during rotary bending, the diameter of and spacing between impurities. The relationship between the fatigue strength and hardness of high-grade steel vs. the quotient of the diameter of impurities and the spacing between impurities was determined. The proposed equations contribute to the existing knowledge base of practices impact of impurities with various diameters and spacing between non-metallic inclusion on fatigue strength.

Abstract

Non-alloy quality case-hardening steels are used for low-load components made on automatic machining centers (automatic lines). Because of the widespread use of these steel in open constructions, they are exposed to atmospheric corrosion. The study attempted to analyze the effect of 20% aqueous NaCl solution on the roughness of the steel as a result of corrosion. The steel roughness and corrosion wear were determined according to corrosion time.

Abstract

The article discusses the effect of large oxide impurities (a diameter larger than 10 μm in size) on the fatigue resistance of structural steel of high purity during rotary bending. The study was performed on 7 heats produced in an industrial plant. The heats were produced in 140 ton electric furnaces. All heats were desulfurized.

The experimental material consisted of semi-finished products of high-grade, carbon structural steel with: manganese, chromium, nickel, molybdenum and boron. Steel sections with a diameter of 18 mm were hardened from austenitizing by 30 minutes in temperature 880°C and tempered at a temperature of 200, 300, 400, 500 and 600°C for 120 minutes and air-cooled. The experimental variants were compared in view of the heat treatment options. Fatigue tests were performed with the use of a rotary bending machine at a frequency of 6000 cpm. The results were statistical processed and presented in graphic form.

This paper discusses the results of the relative volume of large impurities, the fatigue strength for various heat processing options.

Abstract

The paper presents the importance of process security as one of the parts of Total Production Maintenance. Knowledge about the standards and factors used in monitoring production processes has been systematized. The good manufacturing practices in production continuity management are presented in the article.