1, the material standards
Now, we often see the United States imports of stainless steel standard ASME standard SA240, ASTM A240 standards and Japanese JIS standard SUS; grades often used for 304,304L, 316L and so on. 304 The following example to illustrate their representation: JIS standard materials, said the relatively simple, is SUS304 say so; ASME and ASTM, said there are several: SA240-304, SA240TP304, A240-304, A240TP304, in fact, the middle - and plus TP meaning is the same. We have previously mentioned materials 304L, where L is the suffix, indicating a lower carbon content; there can often be seen H, indicates a higher carbon content, mainly used in high temperature applications; also another common There are N, the additional element N, to increase the strength. Sometimes, we can also be seen in the back: 2B, No.1 and other suffixes, these suffix indicates that the surface state of the material; 2B represents hot rolling plus cold rolling, surface better, to mirror the requirements of steel; 2D representation plus cold rolling the hot rolled, the surface of the stainless steel welding wire sheet generally; No.1 represents hot rolling surface.
2, on the alternative materials
In the eyes of many people, materials, "high-generation low-to-generation thin-thick" is the right and proper thing, no more tubes, in fact, this view is wrong, here we 304,304L, 304H example to explain : General view, 304L than 304 have lower carbon content, better corrosion resistance, so you can replace the 304 material. 304L 304 does meet the requirements, and more than 304, seems to automatically replace 304, but the mechanical properties, the strength is higher than 304 304L, when the press 304 is designed with 304L alternative, will result in insufficient strength; In addition, In China Pressure Vessel GB150-1998 in Article 4.1.6: When the temperature is higher than the use of austenitic Stainless steel weaving wire 525 ℃, the carbon content of the steel should be not less than 0.04%. Therefore, that can replace 304 304L using the wrong point of view, and can not be used with the use of the occasion, but also to capacity in accordance with regulatory requirements, we have no right to "material substitution", only the original design department can only be entitled to a "material substitution "work.
