High ductility nickel-free ferrite stainless steel and manufacturing method thereof

Abstract

The invention relates to a high tenacity non-nickel ferrite stainless steel. The components has the mass percentage that: C occupies 0.03 to 0.08 percent, Si is lower than or equal to 1.0 percent, Mn is lower than or equal to 1.0 percent , S is lower than or equal to 0.030 percent , P is lower than or equal to 0.035 percent, Cr occupies 16 to 21 percent, N occupies 0.01 to 0.03 percent, is lower than or equal to 0.0050 percent, rear earth RE occupies 0.02 to 0.1 percent, and the residual is Fe and inevitable foreign impurities. The utility model provides a manufacture method that: firstly, smelting and casting are performed, the time between the adding of rear earth metal and the steel casting is strictly controlled to be lower than or equal to 25 seconds; the casting temperature is controlled at 1550 plus or minus 5 DEG C; secondly, casting ingot or casting blank cogging is performed, the casting ingot or the casting blank can adopt forging cogging or continuous casting continuous rolling, the heating temperature of the casting ingot or the casting blank is 1150 plus or minus 10 DEG C, and the final forging temperature is not lower than 900 DEG C, and the casting ingot or the casting blank is performed with water cooling. thirdly, steel material rolling is performed, the heating temperature is 1160 plus or minus 10 DEG C, the rolling starting temperature is controlled between 1100 to 1150 DEG C, and the final rolling temperature is controlled to be lower than or equal to 800 DEG C, and the casting ingot or the casting blank is performed air cooling; finally, heat treatment is performed. The invention can obviously lengthen the service life under the low temperature condition, and compared with ultra low carbon and nitrogen and nickel-bearing ferrite stainless steel, the performance-price ratio is high.

Description

technical field [0001] The invention belongs to the field of alloy steel, and mainly relates to high-toughness nickel-free ferritic stainless steel and a manufacturing method thereof. Background technique [0002] Ferritic stainless steel does not contain or contains a small amount of precious metal nickel, so compared with austenitic stainless steel with higher nickel content, the cost of the alloy is low, plus some of its inherent characteristics such as chloride stress corrosion resistance, It has excellent local corrosion resistance such as pitting corrosion resistance and crevice corrosion resistance, and has been widely used in civil and industrial applications. [0003] However, it also has some shortcomings and deficiencies, such as poor toughness at room temperature and low temperature, etc., which are prominently manifested in ferritic stainless steel with Cr>16%, which affects the expanded application of medium and high chromium ferritic stainless steel. [00...

AI Technical Summary

Problems solved by technology

However, due to its high carbon and nitrogen content, the solubility in ferrite is very low, so it is difficult to prevent the precipitation of carbon and nitrogen compounds, resulting in poor toughness of the steel (room temperature, low temperature toughness), brittle fracture, and the thickness of the steel used Restricted, it is generally not allowed to exceed 4mm, resulting in short service life of components under low temperature conditions, which cannot meet the requirements of acid tanks and pipelines for chemical equipment in cold climate areas

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