The scientists from the Institute for Problems in Mechanical Engineering of the Russian Academy of Sciences and from the St. Petersburg State University have shown that the method of applying gas-dynamic cold spraying and subsequent laser treatment of stainless steel leads to an improvement in the impact-resistant characteristics of steel.

The results of the study are published in Russian Physics Journal.

Stainless steel is used widely in various industries, including jet engines, power plants, gas and chemical industries. It is used where high strength is required at high temperatures or in aggressive conditions. Stainless steel is used also in the manufacture of hydraulic press valves, turbine blades, cracking plant fittings, cutting tools, springs, household items and in orthopedic dentistry. Besides that, it is used in construction industry and architecture, in food industry, as well as in manufacture of stairs, fences and railings.

In this regard, one of the most important characteristics of steel is its impact resistance, that is, the ability to maintain properties under the influence of environmental impacts. Despite the fact that stainless steel can withstand significant mechanical loads without breaking, its resource is limited and may decrease at extreme temperatures or high-speed loads.

“We have shown the prospects of combined processing of stainless steel: applying a coating by gas-dynamic method and laser treatment of it. As our experiments have shown, this treatment increases the spallation strength of the steel slightly. The method can be considered promising, since even a slight increase in impact resistance is a good result," said Svetlana Atroshenko, a leading researcher at IPMash RAS, a leading researcher at St. Petersburg State University (Elasticity Theory Department).

According to her, gas-dynamic cold spraying makes it possible to obtain a durable metal layer with high adhesion, that is, bonding with steel.

Its advantage over another types of coatings is low temperature, it allows to obtain a coating corresponding to the composition of the initial materials and keeps the substrate material unchanged. Subsequent laser treatment leads to creation of the necessary structure. This combined treatment allows for obtaining the coatings with sufficient thickness, high adhesive strength and required composition.

This treatment increases the dynamic (spallation) strength of stainless steel due to the large number of twins. Twinning is a mechanism of plastic deformation characteristic of impact loading. Laser treatment of the surface layer of the coating led to an increase in the size of the twins and a decrease in their number. With increasing impact velocity, the hardness of the steel increases.