Introduction of high nitrogen high strength stainless steel 304d: Steel characteristics: Take 0.5mm thick cold rolled 2b product as an example, 304 stainless steel yield strength is 280mpa, equivalent to carbon steel Q235; 304d stainless steel yield strength is 420mpa, equivalent to carbon steel q355. In terms of strength level, 304 belongs to austenitic stainless steel of ordinary strength level, and 304 belongs to high-strength austenitic stainless steel. Mechanism: The high strength of 304d stainless steel comes from solid solution strengthening of nitrogen above 2000ppm. In addition to dual-phase steels, conventional austenitic stainless steels such as 304 are difficult to add and solid solution such high nitrogen content, requiring proprietary nitrogen alloying smelting and continuous casting technology. The corrosion resistance of stainless steel can be characterized by pitting corrosion equivalent pren=cr+3.3mo+30n-mn. The higher the pren value, the better the corrosion resistance. Chromium, molybdenum, and nitrogen in stainless steel are all elements that improve the pren value and corrosion resistance. In the alloy design composition of 304d stainless steel, the content of chromium is basically the same as that of 304 stainless steel, but the nitrogen content is much higher than 304, and the contribution of a small amount of residual molybdenum can ensure that the pitting corrosion equivalent of 304d is not less than 19.0. Under normal conditions, j1, 304 The pitting corrosion equivalents of typical components of 304d and 304d were 8.0/18.6/19.1, respectively. Compared with the three, 304d has the highest pit corrosion equivalent pren value, and the corrosion resistance of its welded pipe is no less than 304, both of which are far better than j1.