Diphase stainless steel and manufacturing method thereof

Abstract

The invention discloses a diphase stainless steel, which comprises the following components in percentage by weight: less than or equal to 0.05 percent of C, 0.2 to 1.0 percent of Si, 0 to 2.0 percent of Mn, 22 to 27 percent of Cr, 0 to 2.0 percent of W, less than or equal to 0.1 percent of S, less than or equal to 0.03 percent of P, 0 to 0.003 percent of B, more than 0 and less than or equal to 0.2 percent rare earth of which the Ce content is more than 50 percent, and the balance of Fe and inevitable impurities, wherein a casting blank of the diphase stainless steel comprises over 60 percent of isometric crystal. A method for manufacturing the diphase stainless steel comprises the following steps of: performing smelting, die casting or continuous casting to form the casting blank, wherein the thickness of a steel die is more than 30 mm during the die casting to ensure that the cooling velocity of the steel is more than 10 DEG C per minute, and in the process of the continuous casting, the degree of superheating of the casting is between 30 and 100 DEG C, and the casting speed is over 1.2 meters per minute; putting the casting blank into a heating furnace, heating the casting blank to the temperature of between 1,100 and 1,250 DEG C, performing heat preservation on the casting blank, and then forging or hot-rolling the casting blank to a required thickness; and annealing and pickling a steel plate or a plate coil after forging or hot-rolling, and controlling the annealing temperature to be between 1,000 and 1,100 DEG C. The diphase stainless steel has high corrosion resistance and high hot-working performance, and can be widely applied in the fields of petroleum, chemical industry, papermaking, marine engineering and the like in rigorous corrosion environments.

Description

technical field [0001] The invention relates to a duplex stainless steel containing a ferrite and austenite duplex matrix and a manufacturing method thereof, in particular to a duplex stainless steel with high corrosion resistance, mechanical properties and good thermal processing performance, and the cast slab has more than 60% of the etc. Duplex stainless steel with axial grain content and method of manufacturing the same. Background technique [0002] Duplex stainless steel composed of two phases of austenite and ferrite has superior chloride ion corrosion resistance and stress corrosion resistance, and its yield strength is twice that of 300 series austenitic stainless steel. Duplex stainless steel is widely used in petroleum, chemical industry, papermaking, marine engineering, construction and other fields. [0003] Compared with the traditional 300 series austenitic stainless steel, duplex stainless steel has obvious advantages in terms of performance and economy, but...

AI Technical Summary

Problems solved by technology

However, the increase of N content increases the difference between the strength of the austenite phase and the strength of the ferrite phase in the high temperature state, thereby increasing the tendency of cracks during hot working and deteriorating the hot workability of steel

In addition, the addition of a large amount of Mn also has a negative impact on the corrosion performance.

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