U3 (00Cr25Ni20Mn3Mo3N)

U3 steel has all the element components of A4 steel (A4 is equivalent to 316), and the urine resistant element is added, which has the ability of erosion resistance and corrosion resistance. P4 valve is commonly used in the production of valve core and valve seat in chemical fertilizer industry. The most important corrosion resistance characteristic of U3 steel is that it has much higher passivation ability than 00Cr17Ni14Mo2 (316L) steel. Even under harsh reducing conditions, its passivation film still exists, so as to ensure that this steel has good corrosion resistance. The test shows that at 200 ℃, when the oxygen content in ammonium carbamate solution is only 3ppm, 00Cr17Ni14Mo2 is activated and its corrosion rate is as high as 40mm / A. for 00cr25ni22mo3n steel, its corrosion resistance is still the same and changes little. The higher nitrogen content in U3 steel also increases the higher strength of this material.