Improvement of the properties of low-alloy constructional steels microalloyed with the nitrogen-titan-aluminum complex
Journal Title: Metallurgical and Mining Industry - Year 2017, Vol 9, Issue 3
Abstract
The relevance of research aimed at developing cast cost-effective low-alloy steels with carbonitride hardening due to complex microalloying with inexpensive and accessible elements such as titanium, aluminum and nitrogen is shown. It has been established that for the most effective use of the nitrogen-titanium-aluminum complex when the microalloying of structural steels, it is necessary to create conditions for obtaining maximum amount of fine titanium carbonitrides and to ensure the formation of sufficient number of aluminum nitrides. It is determined that the best quality of the metal is provided at optimal joint micro additives of titanium (0.01-0.03%), aluminum (0.02-0.06%) and nitrogen (0.014-0.020%). At the same time, heat treatment of ferritic-pearlitic steels of (15-20) G (S) ATYUL grade must be carried out in two modes: normalization or quenching at 900-920 °C (during 1.5-2.5 hours) followed by tempering at 650- 690 °C. The use of complex microalloying with nitrogen, titanium and aluminum of steels of (15-20) G (S) L grade allowed achieving the metal grain refining no less than 2 times; increasing in the yield point in the normalized state by 30-80 MPa, and after quenching and high tempering by 60-130 MPa; increasing in cyclic durability of steel by 1.7 times; increasing in yield strength at 250-450 °C by 2.0-2.5 times under industrial conditions.
Authors and Affiliations
G. N. Tregubenko
Keywords
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