OPERATIONAL RELIABILITY OF FORGED BOILER TUBES OF 15Cr1Mo1V STEEL PRODUCED BY NKMZ PJSC

L. V. OPRYSHKO, T. V. GOLOVNIAK

Abstract


Purpose: To assess operational reliability of metal of forged boiler tubes of 15Cr1MoV steel manufactured by NKMZ PJSC (Kramatorsk) based on comprehensive studies of chemical composition, structure and properties, including high-temperature strength. Procedures. Modern methods and procedures of metallographic studies, chemical analysis, tests of short-term mechanical and high-temperature strength properties were used. Results. It has been shown that a distinctive feature of metal of forged tubes of 15Cr1MoV steel manufactured by NKMZ PJSC consists in unfavorable (from the point of view of ensuring high-temperature strength and working capacity) ratio of mass fraction of vanadium to mass fraction of carbon (V/С˂1.6). Metal structure is characterized by inhomogeneity in a relation to distribution of structural components across the wall thickness and along the length of tubes of all sizes under study. In metal of the tubes studied, along with a satisfactory microstructure, objectionable structures were found, which do not provide the level of long-term strength required by the normative documents. Necessity of adjusting chemical composition and conditions of heat treatment of forged boiler tubes made of 15Cr1MoV steel at NKMZ PJSC to ensure a satisfactory structure and required level of service properties in metal of a wide range of tubes was shown. A need to develop a new specification for forged boiler tubes of 15Cr1MoV steel in a wide product range, including requirements for microstructure and conditions of thermal treatment instead of outdated Technical Specification 923 not applied currently in Ukraine, has been established. Scientific novelty. Chemical composition and structure of forged 15Cr1MoV steel tubes  produced by NKMZ PJSC in a wide product range and their effect on long-term strength were established for the first time. Practical value. The obtained study results will serve as a basis for improving technology of production of boiler tubes at NKMZ PJSC and will make it possible to meet the demand of Ukrainian power engineering industry in 620 mm and more diameter 15Cr1MoV Ф steel tubes having high operational reliability.


Keywords


forged boiler tubes; chemical composition; microstructure; short-term mechanical properties; high-temperature strength; long-term strength

References


ТУ 14-3-460/ТУ У 27.2-05757883-207. Трубы стальные бесшовные для паровых котлов и трубопроводов. [Действуют с 01.10.2009]. Днипро : ГП НИТИ, 2009. 50 с. (Технические условия).

ТУ3-923. Трубы котельные бесшовные механически обработанные из конструкционной марки стали. [Действуют с 01.01.1976]. Волгоград : завод «Баррикады», 1975. 10 с. (Технические условия).

Злепко В. Ф., Перевезенцева Т. В., Новиков С. В. О некоторых особенностях структурного состояния металла центробежнолитых паропроводных труб из стали 15Х1М1Ф. Электрические станции. 1991. № 3. С. 12−17.

Опрышко Л. В., Головняк Т. В., Маленик А. О., Козьминский А. Н. Особенности структуры и свойств металла труб из стали 15Х1М1Ф-Ш, изготовленных методом электрошлаковой выплавки. Горнорудная и металлургическая промышленность. 2014. № 2. С. 43−47.

Антикайн П. А. Металлы и расчеты на прочность котлов и трубопроводов : монография. Москва: Энергоиздат, 1990. 386 с.

Крутасова Е. И. Надежность металла энергетического оборудования : монография. Москва: Энергоиздат, 1981. 240 с.

Бугай Н. В., Березина Т. Г., Трунин И. И. Работоспособность и долговечность металла энергетического оборудования : монография. Москва : Энергоатомиздат, 1994. 272 с.

Куманин В. И., Ковалева Л. А., Алексеев С. В. Долговечность металла в условиях ползучести : монография. Москва : Металлургия, 1988. 224 с.

Ланская К. А. Жаропрочные стали : монография. Москва : Металлургия, 1969. 247 с.


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