High intensity and high ductility -50 DEG C low-temperature steel and manufacturing method thereof

Abstract

The invention discloses high-strength high-toughness low-temperature steel at 50 DEG C below zero and a manufacturing method thereof, and belongs to the manufacturing field of low alloy steel. The low-temperature steel comprises chemical compositions in percentage by weight: 0.12 to 0.20 percent of C, 0.15 to 0.50 percent of Si, 1.20 to 1.70 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.010 percent of S, 0.30 to 1.00 percent of Ni, 0.005 to 0.050 percent of Ti, 0.005 to 0.10 percent of Al, 0.010 to 0.050 percent of Nb, one or more than one of less than or equal to 0.10 percent of V, less than or equal to 1.0 percent of Cu, less than or equal to 0.50 percent of Mo, less than or equal to 0.040 percent of Zr, and less than or equal to 0.20 percent of RE, and the balance being Fe. The manufacturing method for the steel comprises the following steps: the heating temperature of steel billets is between 1, 150 and 1, 280 DEG C, the heating rate is between 8and 14 minute / centimeter, the initial rolling temperature of the steel is more than or equal to 1, 100 DEG C, the accumulated reduction rate of control rolling is more than or equal to 60 percent, the reduction rate of each of final three passes is more than or equal to 10 percent, and the final rolling temperature is between 780 and 860 DEG C; and the normalizing heat treatment is adopted, the keeping temperature of the normalization is between 850 and 930 DEG C, and the keeping time is 30-50 minutes+plate thickness (millimeters) x 1 minute / millimeter.

Description

technical field [0001] The invention relates to a high-strength and high-toughness -50°C low-temperature steel and a manufacturing method thereof, belonging to the field of low-alloy steel manufacturing. Background technique [0002] Before the present invention was proposed, there were many similar technical products related to the field of low-alloy steel manufacturing, basically all of which were proposed for special application environments, and had different advantages and disadvantages. There is Chinese Patent Publication No. 200710062013.1 "A Method for Producing Low-Temperature High-Toughness Steel and Its Steel Plate". The Ni content of the steel involved ranges from 8.50 to 10.00%, and the low-temperature impact test temperature is -196°C. There is also the Swedish patent SE442642 "low-alloy high-strength welded steel". Used in -50°C seawater corrosion environment. Another example is the Japanese patent JP592643201 "A Production Method for Low-Temperature High-St...

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Problems solved by technology

16MnDR steel plate is used the most, but according to the user department, the toughness index of 16MnDR steel plate is low, the national standard GB3531 requires -40°C AKV≥27J, and the welding heat affected zone after welding is -40°C It is difficult for AKV to meet the requirement of not less than 20J in the national standard GB150. The strength requirements of 15MnNiDR and 16MnR steel are the same, both of which are Rm≥490MPa, and the Rm≥ of another steel grade 09MnNiDR in the national standard GB3531 440MPa, the wall thickness of the low-temperature pressure vessel in China is relatively large, and the self-weight coefficient increases accordingly, which increases the manufacturing cost of the spherical tank and the labor intensity of the workers

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