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A system based on P5827 and PI50 potentiometers and an IBM PC is considered that makes it possible to investigate electrochemical corrosion of metals and alloys. The system can be used for training students and specialists as well as for corrosion investigation, testing, and certification. The software developed can be used in systems for corrosion protection and cor, d.Publications in this country and abroad give convincing evidence of the expediency of the use of electrochemical methods in corrosion tests [ I -3, 5 -I I ]. These methods are based on modern concepts of the processes of electrochemical corrosion and give reliable data on the type, rate, and mechanisms of corrosion processes. Electrochemical methods can be used in accelerated tests and investigations of the majority of metals and alloys in a wide spectrum of corrosion media and conditions.The system comprises software for determining the corrosion current, corrosion rate, and Tafel coefficients under conditions of uniform corrosion and soft-ware for determining the susceptibility to intercrystallite and pitting corrosion. It has been developed in Pascal in MS DOS. The menu of the system is presented in Table 1.The investigation method is chosen using the HELP and EXP.SYS (expert system) regimes.The HELP regime provides information on the essence of the method, the range of its application, the special features of the software, and data on specifications and publications. The EXP.SYS regime provides the choice of the method with allowance for the tasks of the investigation, the composition of the alloy and the corrosion medium, the requisite accuracy of the computation, the possibilities of the available equipment, and the available experimental data. 228In addition to the software the system includes methodological recommendat.ions and specifications for the methods used. METHODS FOR DETERMINING PARAMETERS OF UNIFORM CORROSIONThese methods are based on the Wagner -Traud equation for the case of activation control, namely,where i, A/m 2 is the density of the external current; E is the running value of the potential, V; Eeo r is the potential of free corrosion; E -E~or is the applied potential; i~o ~ is the density of the corrosion current, A/m2; b m is the Tafel coefficient of anodic ionization of the metal, V; b d is the Tafel coefficient of the cathodic depolarization process, V. The method of polarization resistance standardized in ASTMG 59 [2] is the most widely used. it is based on the linear dependence of the current density i on the applied potential (E -Eco r ) at low values of it [(E -Eco ~) < 60 mV]. In this case we can write the following relationship:

in Fig. 3 reflects the relationship of the total solution rate iaE of Fe-Cr alloys (with a constant potential) to their composition with pH = 0. It may be seen that under these conditions with an increase in chromium content in the alloy iaE first increases and then reaches a limit~

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