1.8978
1.8978 is the material number of the grade also listed as L555MB. It is a material in the category Fine-grain structural steels. We list 5 designations recorded for this grade, in the standards DIN / EN, UNS and AISI / SAE.
- Material no. 1.8978
- Category Fine-grain structural steels · 50 grades
- Designations 5
If you came for one of these
The most-used names for this grade.About Fine-grain structural steels
Fine-grain structural steel is a name for structural steels whose properties are particularly suitable for welding. They have a higher yield strength than comparable steels. Due to the negative influence of carbon on the weldability of a material, the maximum carbon content in fine-grained structural steels is less than 0.2%. These properties are achieved in steelmaking by the addition of oxygen and nitrogen-binding elements. The fine grain in the metallurgical structure is achieved by alloying elements whose nitrides and carbides only dissolve at higher temperatures. With the same composition, they are stronger and tougher than coarse-grained steels. Fine-grained structural steels are used above all in reinforced concrete structures such as bridges, in the construction of cranes, hydraulic cylinders or other welded structures due to their special welding suitability and in the offshore area.
This describes the material class as a whole. Always confirm the individual grade against the standard before ordering.
Also known as
5 designations · 3 standards · nothing hiddenEvery designation on file is listed — no truncation, no “+ n more”. Each one is itself a route that leads back here.
Chemical composition
14 elements on file · weight %What this alloy is
Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade.
| Element | % by weight |
|---|---|
≤ 0.16 | |
≤ 0.45 | |
≤ 1.8 — | |
0.025 | |
0.02 | |
≤ 0.3 | |
≤ 0.1 | |
0.3 | |
≤ 0.1 | |
≤ 0.25 | |
0.015–0.06 | |
≤ 0.06 | |
≤ 0.06 — | |
0.012 |
The scale is logarithmic, not the element’s raw share of the alloy — the only honest way to fit 0.01 % and 100 % in one picture, and it means every value here can be compared with every other.
| Element | As publishedsource text, verbatim | Min% by weight | Max% by weight | Bound |
|---|---|---|---|---|
| C | ≤0,16 | — | 0.160 | Max |
| N | 0,012 | 0.012 | 0.012 | Exact |
| Al | 0,015-0,060 | 0.015 | 0.060 | Range |
| Si | ≤0,45 | — | 0.450 | Max |
| P | 0,025 | 0.025 | 0.025 | Exact |
| S | 0,02 | 0.020 | 0.020 | Exact |
| Ti | ≤0,06 | — | 0.060 | Max |
| V | ≤0,10 | — | 0.100 | Max |
| Cr | ≤0,30 | — | 0.300 | Max |
| Mn | ≤1,80 | — | 1.800 | Max |
| Ni | 0,3 | 0.300 | 0.300 | Exact |
| Cu | ≤0,25 | — | 0.250 | Max |
| Nb | ≤0,06 | — | 0.060 | Max |
| Mo | ≤0,10 | — | 0.100 | Max |
The published column is the source string byte-for-byte, decimal comma and all; Min and Max are the parsed bounds. Elements not listed have no value on file — they are omitted, never inferred.
Predicted transformation temperatures
computed from composition · °CThese four temperatures are a CALCULATION from this grade's own composition, using the published Li, Niebuhr, Meekisho & Atteridge (1998) model — never a measurement, and computed from the UPPER BOUND of each element's specified range, not a mid-range figure. Where this grade also has a measured transformation point (Ac1, Ac3, Ar1, Ar3) on file, it is shown separately, in Physical & mechanical properties, and is never replaced by the predicted figures here — Ae (predicted, equilibrium) and Ac/Ar (measured, on heating or cooling) are different physical quantities and can differ by tens of degrees; a mismatch between the two is not an error in either.
Physical & mechanical properties
An absent property means we hold no value for it — it is left out rather than estimated, interpolated from a neighbouring grade, or filled from a handbook. It does not mean the property is undefined for the material.
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