--- title: "St 45.8/III — Unalloyed structural steels" description: "St 45.8/III in DIN / EN: material number 1.0405, also listed as P255G1TH. Category: Unalloyed structural steels. Designations recorded for this grade: 13." canonical: https://steelequivalents.com/materials/din-en/st-45-8-iii language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/din-en/st-45-8-iii.md cs: https://steelequivalents.com/cs/materiály/din-en/st-45-8-iii.md de: https://steelequivalents.com/de/werkstoffe/din-en/st-45-8-iii.md es: https://steelequivalents.com/es/materiales/din-en/st-45-8-iii.md fr: https://steelequivalents.com/fr/matériaux/din-en/st-45-8-iii.md hu: https://steelequivalents.com/hu/anyagok/din-en/st-45-8-iii.md it: https://steelequivalents.com/it/materiali/din-en/st-45-8-iii.md nl: https://steelequivalents.com/nl/materialen/din-en/st-45-8-iii.md pl: https://steelequivalents.com/pl/materiały/din-en/st-45-8-iii.md pt: https://steelequivalents.com/pt/materiais/din-en/st-45-8-iii.md ru: https://steelequivalents.com/ru/материалы/din-en/st-45-8-iii.md tr: https://steelequivalents.com/tr/malzemeler/din-en/st-45-8-iii.md zh: https://steelequivalents.com/zh/材料/din-en/st-45-8-iii.md ja: https://steelequivalents.com/ja/材料/din-en/st-45-8-iii.md ar: https://steelequivalents.com/ar/المواد/din-en/st-45-8-iii.md ko: https://steelequivalents.com/ko/재료/din-en/st-45-8-iii.md pt-br: https://steelequivalents.com/pt-br/materiais/din-en/st-45-8-iii.md hi: https://steelequivalents.com/hi/सामग्री/din-en/st-45-8-iii.md content_hash: sha256:f0313673c89023ee3b4e1dd1205a4dcd5a71fdea0e042efa06d969df970d0e0b generated: 2026-09-22 --- > **Machine-readable Markdown rendering.** This is a Markdown representation of a web page, > served for AI agents and crawlers as a token-efficient alternative to the full HTML. > Full interactive HTML version: https://steelequivalents.com/materials/din-en/st-45-8-iii > Canonical URL: https://steelequivalents.com/materials/din-en/st-45-8-iii > Available languages: en, cs, de, es, fr, hu, it, nl, pl, pt, ru, tr, zh, ja, ar, ko, pt-br, hi > Change detection: `content_hash` is the SHA-256 of this document's Markdown body — everything > below this block, whitespace-trimmed, excluding the front-matter. Compare it to detect a real > content change; `generated` moves on every render and is not a change signal. DIN / EN · Europe · 13 designations # St 45.8/III St 45.8/III is a designation in DIN / EN for the material held under material number 1.0405, also listed as P255G1TH. It is a material in the category Unalloyed structural steels. We list 13 designations recorded for this grade, in the standards DIN / EN, UNS, ASTM and ČSN. - [*Material no.* **1.0405**](/materials/material-no/1.0405 "Material no.: 1.0405") - [*Category* **Unalloyed structural steels · 452 grades**](/categories/unalloyed-structural-steels "Category: Unalloyed structural steels · 452 grades") - *Designations* **13** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=82ebf0ea-5c51-443e-9cfc-83967339e37f&designation=e0710d90-f31d-4215-9f33-5d00360cd742 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/din-en/st-45-8-iii.pdf "Datasheet as PDF") ## If you came for one of these The most-used names for this grade. - [DIN / EN P255G1TH This grade’s own name](/materials/din-en/p255g1th "DIN / EN P255G1TH") - [UNS K02707 This grade’s own name](/materials/uns/k02707 "UNS K02707") ## About Unalloyed structural steels Unalloyed structural steels include all low-carbon steels in which the iron companions do not exceed specified minimum values. The yield strength, formability and weldability are the decisive factors for their use. They are soft, pliable, tough and stretchy, but cannot be hardened by heat treatment. This describes the material class as a whole. Always confirm the individual grade against the standard before ordering. ## Also known as 13 designations · 4 standards · nothing hidden This grade’s own name recorded in our sources as this grade’s own designation under that standard. Indicative taken from a published cross-reference table; a close match, not a guarantee of interchangeability. Verify against the mill certificate before ordering. Withdrawn designation no longer current — a separate column from the two above, so a name can be same grade and withdrawn at once. Superseded by the current name this withdrawn designation was replaced by — the same grade under its present designation, the one to order by today. DIN / EN Europe · 8 - [1.0405 Indicative](/materials/material-no/1.0405 "DIN / EN 1.0405") - [P255G1TH This grade’s own name](/materials/din-en/p255g1th "DIN / EN P255G1TH")Formerly St 45.8 - [P265GH This grade’s own name](/materials/din-en/p265gh "DIN / EN P265GH") - [P265GH TC1 Indicative](/materials/din-en/p265gh-tc1 "DIN / EN P265GH TC1") - [P265GH TC2 Indicative](/materials/din-en/p265gh-tc2 "DIN / EN P265GH TC2") - [St 45.8 This grade’s own name Withdrawn](/materials/din-en/st45-8 "DIN / EN St 45.8")Superseded by[P255G1TH](/materials/din-en/p255g1th "P255G1TH") - [St 45.8/I Indicative](/materials/din-en/st-45-8-i "DIN / EN St 45.8/I") - **St 45.8/III Indicative** UNS United States · 2 - [K02707 This grade’s own name](/materials/uns/k02707 "UNS K02707") - [K03006 This grade’s own name](/materials/uns/k03006 "UNS K03006") ASTM United States · 2 - [A 106 Grade B Indicative](/materials/astm/a-106-grade-b "ASTM A 106 Grade B") - [A 234 Grade WPB Indicative](/materials/astm/a-234-grade-wpb "ASTM A 234 Grade WPB") ČSN Czechia · 1 - [12022 Indicative](/materials/csn/12022 "ČSN 12022") Every designation on file is listed — no truncation, no “+ n more”. Each one is itself a route that leads back here. ## Chemical composition 5 elements on file · weight % What this alloy is Fe Mn Si C Iron — the balance, never listed by a standard — 98.7 % Mn — 0.8 % Si — 0.2 % C — 0.2 % Traces & impurities · 0.1 % Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade. | Element | % by weight | |---|---| | C | ≤ 0.21 | | Si | 0.1–0.35 | | Mn | 0.4–1.2 | | P | 0.04 | | S | 0.04 | Carbon Silicon Manganese Phosphorus Sulfur 0.01 % 0.1 % 1 % 10 % 100 % 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 published source text, verbatim | Min% by weight | Max% by weight | Bound | |---|---|---|---|---| | C | ≤0,21 | — | 0.210 | Max | | Si | 0,10-0,35 | 0.100 | 0.350 | Range | | P | 0,04 | 0.040 | 0.040 | Exact | | S | 0,04 | 0.040 | 0.040 | Exact | | Mn | 0,40-1,20 | 0.400 | 1.200 | Range | 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 Not enough recorded composition to predict a transformation temperature for this grade — missing: Ni, Cr, Mo. ## Physical & mechanical properties Density 7,85 g/cm³ Exact 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 · 9 values By thickness**Normalized** source `steelnumber` | Thickness mm | ReH N/mm² | Rm N/mm² | |---|---|---| | ≤ 16 | 265 | — | | 16 – 40 | 255 | — | | 40 – 60 | 245 | — | | 60 – 100 | 215 | — | | ≤ 100 | — | 410 – 530 | | 100 – 150 | 200 | 400 – 530 | | 150 – 250 | 185 | 390 – 530 | 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. ## Similar grades — and why Selection rule, stated so you can disagree with it: same number class 1.0, a shared category, and a published range for Mn / Si that overlaps this grade’s. These are neighbours in composition space — they are not equivalents, and none is claimed to be interchangeable with this grade. [P235S 1.0112 Mn 0,40-1,20 · Si ≤0,35 - ΔMn 0.00 - ΔSi 0.05 - 9 designations](/materials/din-en/p235s "P235S")[S355JR 1.0045 Mn ≤1,60 · Si ≤0,55 - ΔMn 0.00 - ΔSi 0.05 - 32 designations](/materials/din-en/s355jr "S355JR")[S320GP 1.0046 Mn ≤1,60 · Si ≤0,55 - ΔMn 0.00 - ΔSi 0.05 - 3 designations](/materials/din-en/s320gp "S320GP")[S355GP 1.0083 Mn ≤1,60 · Si ≤0,55 - ΔMn 0.00 - ΔSi 0.05 - 5 designations](/materials/din-en/s355gp "S355GP")[P235G1T1 1.0253 Mn ≤1,60 · Si ≤0,55 - ΔMn 0.00 - ΔSi 0.05 - 3 designations](/materials/din-en/p235g1t1 "P235G1T1")[P275T1 1.0256 Mn ≤1,60 · Si ≤0,55 - ΔMn 0.00 - ΔSi 0.05 - 7 designations](/materials/din-en/p275t1 "P275T1") ## Looking for this grade under another name? Search the catalogue by designation, material number or composition — every name on this page is itself a way in. [Search](/search "Steel grade search")[Inquiry](/inquiry?material=82ebf0ea-5c51-443e-9cfc-83967339e37f&designation=e0710d90-f31d-4215-9f33-5d00360cd742 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/din-en/st-45-8-iii.pdf "Datasheet as PDF")