Problems with the new 0Cr18Ni9 grade
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This post was last edited by Langyan on 2009-8-31 17:08. JB4237-2007 has changed the grade from 0Cr18Ni9 to 06Cr19Ni10. Why was this change made? I remember that the numbers of the original grade were related to the content of that metal in the material; so what do the new grades represent?
This post was last edited by New little friend on 2009-8-31 15:50. The requirements regarding the composition have changed; the carbon content has been reduced. It seems like there isn’t a version from 2007 yet? However, the grade 0Cr18Ni9 has indeed been changed, according to the standard GB/T20878-2007 \"Steel grades and chemical compositions – Stainless steels and heat-resistant steels\".
The new grade specifies more clearly the requirements for carbon content; the number before Cr indicates the carbon content in parts per ten thousand.
Increasing the Cr content helps prevent stress corrosion and intergranular corrosion... Increasing the carbon content... I think that’s the purpose; the composition changes, but the allowable stress remains similar
JB4237-2007 has changed the grade 0Cr18Ni9 to 06Cr19Ni10, where 06 indicates the carbon content, 19 indicates the chromium content, and 10 indicates the nickel content
1) Old designation: The number before Cr indicates the percentage of carbon by thousand. Such as 201 (1Cr17Mn6Ni5N): carbon (C) content in parts per thousand ； 2Cr13 (420) and 7Cr17 (440A) denote carbon (C) contents of two thousandths and seven thousandths, respectively ； If C ≤ 0.08%, it is considered low carbon, and it is denoted as “0”, such as (304) 0Cr18Ni9 ； C≤0.03% is ultra-low carbon, denoted as “00”, such as 00Cr17Ni14Mo2 (316L). 2) New grade: The digit before Cr indicates the percentage by ten-thousand of carbon (C) content. For example, the grade 201 is 12Cr17Mn6Ni5N, which indicates that the carbon (C) content is 0.12% or twelve parts per ten thousand ； The 304 grade is 06Cr19Ni10, indicating a carbon (C) content of 0.06% by ten-thousand ； The 316L grade is 022Cr17Ni12Mo2, indicating a carbon (C) content of 0.022% (two thousandths two). Other identifiers remain basically unchanged. The carbon (C) content in the new grades is more precisely defined than before, and higher requirements are placed on the product manufacturing techniques.
Changing the part number, just like changing Chinese characters, is a pointless effort that only causes trouble for the manufacturer
After making the changes, one still needs to get familiar with the new material gradually
The ingredients have remained largely unchanged; the only change is the name, which has forced us to find alternative materials!
The stainless steel standard is not JB4237-2007, but GB/T4237-2007 \"Hot-rolled stainless steel sheets and strips\".