Normalized high-strength low-yield-ratio pressure vessel steel with temperature of minus 70 DEG C and manufacturing method thereof

Abstract

The invention provides normalized high-strength low-yield-ratio pressure vessel steel with the temperature of minus 70 DEG C. The normalized high-strength low-yield-ratio pressure vessel steel with the temperature of minus 70 DEG C comprises, by mass percentage, 0.10-0.20 of C, not larger than 0.10 of Si, 1.00-2.00 of Mn, not larger than 0.010 of P, not larger than 0.002 of S, 0.005-0.050 of Alt,not larger than 0.50 of Cu, not larger than 0.50 of Cr, not larger than 0.50 of Mo, 0.01-0.05 of Nb, 0.02-0.06 of V, 0.50-1.00 of Ni, not larger than 0.004 of N and the balance Fe and unavoidable inclusions, wherein Cu, Cr, and Mo satisfy the condition that, by mass percentage, the sum of [Cu], [Cr] and [Mo] is larger than or equal to 0.40 and smaller than or equal to 0.90. By the adoption of thenormalized high-strength low-yield-ratio pressure vessel steel with the temperature of minus 70 DEG C and a manufacturing method of the normalized high-strength low-yield-ratio pressure vessel steel with the temperature of minus 70 DEG C, through composition design, inclusion control, rolling and heat treatment, the steel is high in strength, high in low-temperature obdurability and low in yield ratio and can be used for manufacturing various low-temperature movable pressure vessels.

Description

technical field [0001] The invention relates to the field of pressure vessel steel manufacturing, in particular to a -70°C normalized high-strength and low-yield-ratio pressure vessel steel and a manufacturing method thereof. Background technique [0002] With the rapid development of my country's energy, petrochemical, chemical and city gas industries, liquefied gas tankers play an important and indispensable role in the transportation of liquid (or gas-liquid) fuels and chemical raw materials due to their flexibility and convenience. substitute role. The steel used for the tank body of liquefied gas vehicles in my country has always used 16MnR steel with a lower strength level (Rm is 510MPa grade), resulting in a thicker wall thickness of the tank body, resulting in a large self-weight coefficient of the existing tank car, a small volume-to-weight ratio, and low carrying efficiency. backward state. At the same time, the service temperature of normalized high-strength press...

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Problems solved by technology

However, the low-temperature toughness of this steel

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