Method for production of a seamless steel tube having grains of austenite with a number of grain size according to ASTM E 112 more than or equal to 7.2

摘要

Method of production of steel tube semcostura.The present invention relates to a seamless steel tube produced by heating a steel bar, which has a chemical composition C: 0.15 to 0.20%, Si: no less than 0,01% less than 0,15%.Mn, 0.05 to 1.0%, Cr: 0.05 to 1.5%, Mo: 0.05 to 1.0%, al: 243 0,10%, V: 0.01 to 0.2%, Ti: 0002 to 0.03%, B: 0.0003 to 0.005% and N: 0.002 to 0.01%, optionally one or more elements between CaMg and REM in a specific amount, under the condition that the terms "0 + (Mn / 6) + (cri5) + (Mo / 3) 242 0.43" and "you x n syn within 0.0006 X "are satisfied with the balance being Fe and impurities, where p 243 0.025%, 243 u2265 0010% and Nb 243 0005% entreas impurities, to a temperature of 1000 to 1250.198 C followed by laminating tube production the end temperature of rolling from 900 to 1050 198 C,And then cooled - on the steel tube due to direct the mind of a temperature not lower than the transformation point air ~ 3 ~ followed by tempering at a range of temperatures of 600 C at 198It is the point of processing AC ~ 1 ~, or instead of the above mentioned lamination after the production of the tube.Warming up is in addition the steel tube resulting in a range of temperatures of the transformation point AC ~ 3 ~ up to 1000 198 C on the line and then is cooled off even in a 'PeraTemperature not lower than the transformation point air 3 followed by tempering at a range of temperatures of 600 198 C to the point of processing AC ~ 1 ~,It has high strength and excellent toughness, and at the same time has a high rate of income and is also excellent in resistance SS0.