эксресс-метод определения марки металла по искре

Environment. Technology. Resources, Rezekne, Latvia Proceedings of the 10th International Scientific and Practical Conference. Volume I, 157-161 Explanation of the express method of the determination of steel grade by spark Igor Nikiforov1, Pavel Maltsev1, Vladimir Ivanov1, Inna Barsuk2 Pskov state university, Faculty of Mechanical and machine building, Departament of Technology of machinebuilding. Address: Lenin square 2, Pskov, 180000, Russian Federation 2 Pskov state university, Faculty of Mechanical and machine building, Departament of Theory of machinery and machines. Address: Lenin square 2, Pskov, 180000, Russian Federation. 1 Abstract. On the basis of physico-chemical theory of burning metal particles, the explanation known method of determining the grade of steel for the spark when it is grinding is performed. The features of formation of globules are reviewed and given them a brief description. The conditions for the formation of a spark in the processing of steels and alloys of various grades are researched. Keywords: grinding, chips, spark, combustion, diffusion oxidation, globule, thermal defect. I INTRODUCTION In the recent past, is widely used express method of determining the grade of steel by spark when grinding the sample [1]. This method is currently losing relevance, since many machine building plants has modern equipment for the chemical and spectral analysis. However, it is sometimes used, since it does not require expensive equipment, and if used properly, gives satisfactory results. Specified express method most in demand in the repair industry, at small plants. Some of the steel, irons, hard alloys and nonferrous metals shows in Table I, moreover therein the characteristic of the beam sparks when grinding is submitted [2]. As seen from the table, the hallmarks of sparks during grinding of various materials are color sparks (at the beginning - i.e. near the grinding wheel, and at the end of the flight); volume of the beam sparks; maximum length of the flight; amount of flashes in sparks beam and the nature of their demonstrations (in the form of a bifurcation, or in the form of the "stars" - when scatter of a small sparks in different directions is take place). Analysis occurring physical and chemical processes that underlie the said express method can promotes to a more correct understanding of phenomena and processes existent in the grinding surfaces of workpieces. Since diffusion-oxidation processes occurring on the surface of the workpiece and during combustion of the chips are very similar and taking place at significant temperatures (up to 1500 ° C and above [3]). As a result, thermal defects appear on the surface of workpieces: burns (visible and invisible), microcracks and phase transformation. Clearly, the method of determination of steel grade and other metals by spark based on the specifics of burning metal chips after her removal from the area of grinding. The combustion process is primarily affected by: the initial temperature of the chips, the nature of its heat exchange with the environment, the diffusion-oxidation processes, the strength characteristics of the outer oxide layer and the value of the activation energy [4]. The exothermic oxidation reaction (with discharge of heat) is occur after the remove of the hot chips from the grinding zone. Metal is oxidized and if the temperature of surface of chips exceeds the melting temperature of the oxide film, then there is burning. In this cas