INFLUENCE OF HEAT TREATMENT ON THE PECULIARITIES OF LOCAL CORROSION OF 08H18N10 STAINLESS STEEL IN WATER ENVIRONMENT

Abstract

Establishment of the effect of heat treatment on the corrosion resistance of 08H18N10 stainless steel ofausteniticclassin an aqueous medium and peculiarities of local corrosion. Standard methods were used: resistance testing against pitting andintergranular corrosion and corrosion cracking, spectral analysis method, optical metallography. The influence of two modes of heat treatment on the sensitivity of 08H18N10 stainless steel ofausteniticclassto local types of corrosion: corrosion cracking, pitting andintergranular corrosion was investigated. It was found that heat treatment in the temperature range from 860 to 970 ^oCin some extent increases the resistance against corrosion cracking compared to the sample in the initial state, but the formation of chromium carbides at the boundaries of austenitic grains, which causes intergranular corrosion and reduces pitting resistance are take place. Increasing the heat treatment temperature to (910-1080) ^oC provides satisfactory resistance to corrosion cracking, does not cause intergranular corrosion and does not impair the resistance to pitting. According to the results of a complex study, data on the influence of heat treatment regimes on the resistance of stainless steel against local corrosion such as: corrosion cracking, pitting andintergranular corrosion were obtained. The stability of the manufactures made of 08H18N10 steel in the aqueous medium as a whole will be determined by the resistance against that type of local destruction to which the steel is least resistant. Since the endurance of the product as a whole will be determined by the resistance to the such type of local destruction to which the least resistance is found, heat treatment at a temperature of (910-1080) ^oC is determined to be rational. According to the research results, the heat treatment regime of corrugated pipe of stainless steel 08H18N10, using of which provides satisfactory resistance against corrosion cracking in water and does not impair the resistance against intergranular and pitting corrosion is substantiated.