304 304L Dual Certified
for stainless steel plate, 304 / 304L dual certified stainless steel conform to ASTM A240, we check it in this aspect, in fact, it is almost the same in chemical composition and properties, dual certification is always required in two very similar alloys, not for big difference grade.
Firstly, let us see 304 and 304L and comparing in difference, usually, we consider 304L is low carbon 304, and variation from 304, “L” means low content in carbon element.
| Grade | C | Si | Mn | Cr | Ni | Mo | S | P |
|---|---|---|---|---|---|---|---|---|
| 304 | 0,08 | 1,0 | 2 | 18 – 20 | 8 – 11 | – | 0,03 | 0,045 |
| 304L | 0,035 | 1,0 | 2 | 18 – 20 | 8 – 12 | – | 0,03 | 0,045 |
From above table, we can see that there are two differences in composition, Carbon and Nickel content, Nickel content range from 8 to 12% for 304L, and 304 Nickel content range from 8 to 11%, it is not so that important, carbon content of 304 / 304L dual certification must not exceed 0.035%.
Secondly, let us check 304 and 304L stainless steel mechanical properties in minimum value.
| Grade | Tensile Strength(Mpa) | Yield Point(Mpa) | Elongation(%) |
|---|---|---|---|
| TP304 | 515 | 205 | 35 |
| TP304L | 485 | 170 | 35 |
Versus to 304L, 304 has higher value in Tensile strength and Yield point due to high carbon content, so 304/304L dual certification limit to that two properties minimum 515 Mpa and 205 Mpa separately.
Important: Type 304L can be dual certified as 304 when the composition meets the lower carbon limit of 304L and the slightly higher strength levels of 304.
