In this research work the classification of defects of castings obtained by electric arc smelting is considered. Of particular interest to researchers is the rock-like and naphthalene fractures. A stone-like fracture is characterized by a clearly defined uniform surface over which the fracture occurs. Grain boundaries are partially soluble in the austenite phase, consisting of fine individual particles or films formed from molten eutectics. It is also worth noting that most often the stone-like fracture is observed at the grain boundaries.

Foundry steels are widely used in modern engineering today. But it is foundry steels that have the greatest number of defects, which can be detected by macro-and microanalysis. In addition, with the help of these studies, you can get an idea about the General structure of the metal and the presence of certain specific defects in it – stone-like and naphthalene fractures. Using microanalysis methods, it is also possible to evaluate the properties of multiphase alloys and cast iron, for which there are special scales that classify graphite and phosphide eutectic by shape and quantity. The article describes the features of conducting these studies using optical microscopy.

In the modern automotive industry, heat engine pistons must have sufficient strength characteristics to ensure the necessary reliability and durability under high dynamic, mechanical and thermal loads. Currently, aluminum alloys, cast iron, steel and composite materials are used in domestic and international practice for the production of pistons. The use of cheap reinforcing elements made of carbon materials instead of expensive ceramic and boron fibers, silicon carbide particles will significantly reduce the cost of pistons and make them more affordable for mass production.

Due to the increase in the specific power of heat engines, one of the most pressing problems of modern engineering is the increase in the contact strength and heat resistance of piston aluminum alloys. The article considers the main promising methods of strengthening piston aluminum alloys in the aspect of modern technologies. Long-term operation of heat engines in operating conditions close to critical conditions contributes to melting of the grain boundaries of piston alloys, which negatively affects the reliability of internal combustion engines. In General, the task of increasing the heat resistance of piston aluminum alloys is one of the main tasks of modern engineering.

The article presents regulating characteristics of a diesel engine according to the fuel injection advance angle during the work of engine on a gas-diesel process. Currently, for many manufacturers the task of reducing production costs is a key priority. In agriculture the essential expenditure item is made up of costs for mobile power facilities fuel. One way to decrease these costs is to use alternative, cheaper fuels. Natural gas is one of them. Diesel is the most common type of engine in agriculture. Though a lot of research on converting diesel engines to natural gas have been carried out, the problem of transition of high performance diesel engines of low dimension to natural gas is still understudied. Diesel D-245.7 (4CHN11/12.5) was taken as the object for the research. The aim of study is converting diesel to a gas-diesel process. Carrying out bench tests with recording regulating characteristics according to the fuel injection advance angle was one of the research stages. As the result of the bench tests there have been established the parameters of the combustion process, heat release characteristics, and effective indicators at different fuel injection advance angles when working on diesel and gas-diesel process.