Q420B
Q420B is a grade designated under GB. Its recorded composition includes C ≤ 0.2%, Si ≤ 0.5%, Cr ≤ 0.3%, Mn ≤ 1.7% and Ni ≤ 0.8%. No cross-standard equivalents are recorded for this grade yet. Recorded mechanical properties include Rm 500–680 N/mm², Re 340–420 N/mm² and A 18–19%; these figures vary with the delivery condition and dimension.
- Designations 1
Chemical composition
13 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 |
|---|---|
≤ 0.2 | |
≤ 0.5 | |
≤ 1.7 | |
≤ 0.035 | |
≤ 0.035 | |
≤ 0.3 | |
≤ 0.2 | |
≤ 0.8 | |
≤ 0.2 | |
≤ 0.3 | |
≤ 0.2 | |
≤ 0.07 | |
≤ 0.015 |
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 | ≤0.2 | — | 0.200 | Max |
| N | ≤0.015 | — | 0.015 | Max |
| Si | ≤0.5 | — | 0.500 | Max |
| P | ≤0.035 | — | 0.035 | Max |
| S | ≤0.035 | — | 0.035 | Max |
| Ti | ≤0.2 | — | 0.200 | Max |
| V | ≤0.2 | — | 0.200 | Max |
| Cr | ≤0.3 | — | 0.300 | Max |
| Mn | ≤1.7 | — | 1.700 | Max |
| Ni | ≤0.8 | — | 0.800 | Max |
| Cu | ≤0.3 | — | 0.300 | Max |
| Nb | ≤0.07 | — | 0.070 | Max |
| Mo | ≤0.2 | — | 0.200 | 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.
Properties by condition
1 conditions · 18 valuescaishuku| Thicknessmm | RmN/mm² | ReN/mm² | A% |
|---|---|---|---|
| ≤ 16 | 520 – 680 | ≥ 420 | ≥ 19 |
| 16 – 40 | 520 – 680 | ≥ 400 | ≥ 19 |
| 40 – 63 | 520 – 680 | ≥ 380 | ≥ 18 |
| 63 – 80 | 520 – 680 | ≥ 360 | ≥ 18 |
| 80 – 100 | 520 – 680 | ≥ 360 | ≥ 18 |
| 100 – 150 | 500 – 650 | ≥ 340 | ≥ 18 |
Every figure holds only for the condition on its own row. Values are never merged across conditions or across sources, never averaged, and never interpolated between two rows. An em dash means no value on file — never zero. Figures are converted to the unit in the column header; the source’s own wording is kept and shown where the two differ.
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