620.194 We present the results of investigation of some pipe and structural steels as well as their welded joints on the resistance to sulfide cracking. We show that refinement of pearlitic pipe steels by known methods can improve their resistance to the level of the best hydrosulfide-resistant steels of foreign firms.Sulfide cracking of pipelines and oil and gas equipment has become an urgent problem in recent years due to the development of oil and gas deposits, in particular, the shelf region of the Black Sea containing hydrogen sulfide.The NACE TM 01-77-90 method is conventional for a quantitative estimation of the resistance of steels and alloys as well as their welded joints to sulfide cracking. According to the method, specimens with a diameter of 6.4 mm (lp = 25.4 mm) are tested under static loading in NACE solution (a 5% NaC! solution + 0.5% CH 3 COOH + H 2 S, saturation to 1800-2600 mg/liter) at 20-25~ Susceptibility to corrosion cracking is estimated by using the threshold stress ~Tth on the base of 720 h [ 1 ].In the present work, we study the most typical steels of pearlitic class and certain structural steels of other classes as well as, for comparison, two types of titanium alloys ( Table 1). The ratio (Yth/(Yy ((Y0.2) is a nonstandard but conventional criterion of the serviceability of alloy in media with a high content of hydrogen sulfide. If the ratio is greater than 0.8, then the material corresponds to the requirements of the work for the above-mentioned conditions. If the material is intended for welded objects, then specimens are made of blanks welded and thermally treated according to modes which eliminate residual postwelded stresses in walls.Pipe steels were also tested for susceptibility to hydrogen-induced cracking according to NACE TM-02-84 standard because this test is compulsory in choosing the material of pipelines for transportation of products with hydrogen sulfide impurities. The essence of the method is holding for 96 h of idle specimens (100 x 20 x h, ram) in a synthetic sea water (a 3.5% NaC1 solution, 25~ saturated with hydrogen sulfide followed by an analysis of damage of the metal by internal cracks. If colonies of cracks in the direction of the texture of the metal (zones of crack formation) are present in subsurface layers of the metal (across the thickness of the specimen), then one calculates the criterion of sensitivity of steels to hydrogen cracking (coefficients of length and thickness of crack formation).Note, first of all, that all the pipe steels (20, 20YuCh, 14GB, and 17GS) under investigation have no sensitivity to hydrogen cracking. Cracks appear in a weld and near it only in 16-mm-thick stressed welded joints of 14GB steel.In addition to the mentioned pipe steels, we investigated structural weld steels (pearlitic 12KhlMF steel with granular pearlite, sorbite-hardened 10KhN5MF, pearlitic-martensitic 20Kh13, and austenitic-martensitie 02Kh20N6M3 steels as well as titanium (commercially pure titanium) VTI-0 alloys and AT3 pseudo a'-titanium (Table 1).The most...

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