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The mechanical properties of the steel were determined by subjecting specimens cut from pipes-layers of multilayer packets to static tensile tests at room temperature. The results obtained (Table i) suggest that the mechanical properties of the steel are functions of the nitrogen concentration (fraction of total means) and grain size. Note that with other conditions equal, an increase in the nitrogen fraction of the total mass exerts a major influence on the ultimate strength, while a reduction in grain size has a significant effect on yield point. For similar grain sizes, therefore, an increase in the nitrogen fraction of the total mass from 0.33 to 0.58% leads to a 90 MPa increase in the ultimate strength type 22-10~2 steel on average, despite a lower carbon concentration, while a grainsize reduction of from 9-10 to 12-13 increases the yield point by 140 MPa for the same nitrogen and carbon fraction in the total mass. As compared with steel 08KhI8NIOT, the ultimate strength of all the steels tested is 1.5 times greater, and the yield point more than two times greater with retention of a sufficiently high level of plasticity. It should be noted that a significant level of strength characteristics, which often exceeds the level attained for liquid-phase alloying even with a coarser metal grain (right up to size 6), is observed in pipes formed from steels with a nitrogen fraction of ~0.6% of the total mass, which are produced by the SDAN method. On the one hand, this enables us to expect an even greater hardening under the same temperature conditions with grain-size reduction; in light of notions concerning the mechanism of creep above the equicohesive temperature (~500~ for this type of steels) [3], on the other hand, the high strength of highnitrogen steel with a rather coarse grain is extremely suitable for the operation of bellows. In the latter case, alloying with nitrogen tends to lessen the contribution of the grain boundaries to creep; in this case, the higher the nitrogen content in the steel

Realization of the gradual failure of the pump is hindered by the instability of the dimensions of the delivery, the reasons for which are not connected with the technical state of the pump. This also distorts the value of the indices of the reliability of well pumps, determined on the basis of an analysis of statistical data. A decrease in the possibility of error in making a decision on the need to replace a well pump, and a lowering of the error in determination of indices of reliability can be achieved by an equalization of the empirical curve of the change in the delivery coefficients of the pump with the time, on the basis of a mathematical model. The known mathematical models [I-3] describing the law of change in the delivery coefficients of a well pump with time do not take account of the instability of the delivery, since they were obtained without equalization of the actual curves, and were derived theoretically. In [|] the value of the actual initial delivery of the pump was also left out of consideration.

The authors determine the most accurate expression for the two-sided load application that has to be used in the stress analysis of gear transmissions of pumping jack reduction gears. To solve the problem, the authors make use of the theory of limit cycles in asymmetric loading of metal specimens and components.