Method of improving the structure and properties of pipes from low-alloy steels

Abstract

Purpose − increase of properties of pipes and other rolled products from low-alloy steels by application of scientifically reasonable technology of heat treatment. Methodologies. Research of micro- and fine structure of pipes from low-alloy steels was carried out by the methods of light and electron microscopy, the corrosive tests of standards of pipes are conducted on methodology of NACE ТМ 0177; determination of mechanical properties − by tests on a stretch and shock bend at negative temperatures. Results. It is worked out and tested on pipes from low-alloy steels 06X1-Y and 30XMА new mode of heat treatment, that includes tempering and brief double tempering at high temperatures (oС): (Ас1 − 10) + (Ас1 − 30), close to the start temperature of α→γ transformation. Development allows to promote resistance against the sulfide corrosive cracking under tension and descriptions of durability of pipes at maintenance of high plasticity. Scientific novelty. First by the method of electronic microscopy, microdiffraction and double stereography projections the special low-energy CSL grain boundary (SGB) are found in the martensite and banit structures of low-alloy steels. It is well-proven that SGB is saved in the structure of steels after heat treatment on the worked out technology. Practical utility. Development allows to improve properties of pipes and other rent from low-alloy steels and can be carried out on the operating equipment of plants without additional capital costs.