--- title: "50B — Unalloyed structural steels" description: "50B in GB: material number 1.0045, also listed as S355JR. Category: Unalloyed structural steels. Designations recorded for this grade: 32." canonical: https://steelequivalents.com/materials/gb/50b language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/gb/50b.md cs: https://steelequivalents.com/cs/materiály/gb/50b.md de: https://steelequivalents.com/de/werkstoffe/gb/50b.md es: https://steelequivalents.com/es/materiales/gb/50b.md fr: https://steelequivalents.com/fr/matériaux/gb/50b.md hu: https://steelequivalents.com/hu/anyagok/gb/50b.md it: https://steelequivalents.com/it/materiali/gb/50b.md nl: https://steelequivalents.com/nl/materialen/gb/50b.md pl: https://steelequivalents.com/pl/materiały/gb/50b.md pt: https://steelequivalents.com/pt/materiais/gb/50b.md ru: https://steelequivalents.com/ru/материалы/gb/50b.md tr: https://steelequivalents.com/tr/malzemeler/gb/50b.md zh: https://steelequivalents.com/zh/材料/gb/50b.md ja: https://steelequivalents.com/ja/材料/gb/50b.md ar: https://steelequivalents.com/ar/المواد/gb/50b.md ko: https://steelequivalents.com/ko/재료/gb/50b.md pt-br: https://steelequivalents.com/pt-br/materiais/gb/50b.md hi: https://steelequivalents.com/hi/सामग्री/gb/50b.md content_hash: sha256:ee956935000b8885c5b7fc875a22ae7f5f1277510fec8259336df4a01192253b generated: 2026-09-24 --- > **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/gb/50b > Canonical URL: https://steelequivalents.com/materials/gb/50b > 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. GB · China · 32 designations # 50B 50B is a designation in GB for the material held under material number 1.0045, also listed as S355JR. It is a material in the category Unalloyed structural steels. We list 32 designations recorded for this grade, in the standards DIN / EN, UNS, AISI / SAE, BS, AFNOR, UNE, ISO, JIS, GB, NP, UNI, SS, PN, ABNT NBR, MSZ, SANS, NBN and CSA. - [*Material no.* **1.0045**](/materials/material-no/1.0045 "Material no.: 1.0045") - [*Category* **Unalloyed structural steels · 452 grades**](/categories/unalloyed-structural-steels "Category: Unalloyed structural steels · 452 grades") - *Designations* **32** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=8811cfee-ad48-489e-93c2-300d80648457&designation=f7cb533c-7ba9-4933-a974-f4e7c4289175 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/gb/50b.pdf "Datasheet as PDF") ## If you came for one of these The most-used names for this grade. - [DIN / EN S355JR This grade’s own name](/materials/din-en/s355jr "DIN / EN S355JR") - [UNS K02404 This grade’s own name · 4 grades on that route](/materials/uns/k02404 "UNS K02404") ## 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 32 designations · 18 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. DIN / EN Europe · 4 - [Fe510B Indicative](/materials/uni/fe510b "DIN / EN Fe510B") - [S355JR This grade’s own name](/materials/din-en/s355jr "DIN / EN S355JR") - [SSGrade50 Indicative](/materials/din-en/ssgrade50 "DIN / EN SSGrade50") - [St52-3 Indicative](/materials/din-en/st52-3 "DIN / EN St52-3") UNS United States · 2 - [K02404 This grade’s own name](/materials/uns/k02404 "UNS K02404") - [K02702 This grade’s own name](/materials/uns/k02702 "UNS K02702") AISI / SAE United States · 3 - [A572 Indicative](/materials/astm/a572 "AISI / SAE A572") - [A678Gr.A Indicative](/materials/aisi-sae/a678gr-a "AISI / SAE A678Gr.A") - [SSGrade50 Indicative](/materials/din-en/ssgrade50 "AISI / SAE SSGrade50") BS United Kingdom · 2 - **50B Indicative** - [Gr 50B Indicative](/materials/bs/gr-50b "BS Gr 50B") AFNOR France · 1 - [E36-2 Indicative](/materials/afnor/e36-2 "AFNOR E36-2") UNE Spain · 1 - [AE355B Indicative](/materials/une/ae355b "UNE AE355B") ISO International · 2 - [E355C Indicative](/materials/afnor/e355c "ISO E355C") - [Fe510B Indicative](/materials/uni/fe510b "ISO Fe510B") JIS Japan · 2 - [SM490A Indicative](/materials/ks/sm490a "JIS SM490A") - [SS490 Indicative](/materials/jis/ss490 "JIS SS490") GB China · 3 - **50B This grade’s own name** - [Q345B Indicative](/materials/gb/q345b "GB Q345B") - [Q345C Indicative](/materials/gb/q345c "GB Q345C") NP Portugal · 1 - [FE510-B Indicative](/materials/uni/fe510b "NP FE510-B") UNI Italy · 1 - [Fe510B Indicative](/materials/uni/fe510b "UNI Fe510B") SS Sweden · 1 - [2132-01 Indicative](/materials/ss/2132-01 "SS 2132-01") PN Poland · 1 - [18G2A Indicative](/materials/pn/18g2a "PN 18G2A") ABNT NBR Brazil · 3 - [NBR 5000 Grau 35 Indicative](/materials/abnt/nbr-5000-grau-35 "ABNT NBR NBR 5000 Grau 35") - [NBR 5004 Grau Q35 Indicative](/materials/abnt/nbr-5004-grau-q35 "ABNT NBR NBR 5004 Grau Q35") - [NBR 7007 AR350 Indicative](/materials/abnt/nbr-7007-ar350 "ABNT NBR NBR 7007 AR350") MSZ Hungary · 1 - [Fe 355 B Indicative](/materials/msz/fe-355-b "MSZ Fe 355 B") SANS South Africa · 1 - [350 WA Indicative](/materials/sans/350-wa "SANS 350 WA") NBN Belgium · 1 - [AE355B Indicative](/materials/une/ae355b "NBN AE355B") CSA Canada · 2 - [350W Indicative](/materials/csa/350w "CSA 350W") - [350WT Indicative](/materials/csa/350wt "CSA 350WT") Every designation on file is listed — no truncation, no “+ n more”. Each one is itself a route that leads back here. ## Chemical composition 7 elements on file · weight % What this alloy is Fe Mn Si Cu Iron — the balance, never listed by a standard — 97 % Mn — 1.6 % Si — 0.6 % Cu — 0.6 % Traces & impurities · 0.3 % Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade. | Element | % by weight | |---|---| | C | ≤ 0.24 | | Si | ≤ 0.55 | | Mn | ≤ 1.6 | | P | 0.035 | | S | 0.035 | | Cu | ≤ 0.55 | | N | 0.012 | Carbon Silicon Manganese Phosphorus Sulfur Copper Nitrogen 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 | ≤0,24 | — | 0.240 | Max | | N | 0,012 | 0.012 | 0.012 | Exact | | Si | ≤0,55 | — | 0.550 | Max | | P | 0,035 | 0.035 | 0.035 | Exact | | S | 0,035 | 0.035 | 0.035 | Exact | | Mn | ≤1,60 | — | 1.600 | Max | | Cu | ≤0,55 | — | 0.550 | 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 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 3 conditions · 46 values By thickness**Flat and long products** source `steelnumber` | Thickness mm | ReH N/mm² | Rm N/mm² | |---|---|---| | ≤ 3 | — | 510 – 680 | | 3 – 100 | — | 470 – 630 | | ≤ 16 | 355 | — | | 16 – 40 | 345 | — | | 40 – 63 | 335 | — | | 63 – 80 | 325 | — | | 80 – 100 | 315 | — | | 100 – 150 | 295 | 450 – 600 | | 150 – 250 | — | 450 – 600 | | 150 – 200 | 285 | — | | 200 – 250 | 275 | — | By thickness**no delivery state stated** source `steelnumber` | Thickness mm | A80% · Lo = 80 mm | A% · Lo = 5,65 √So | |---|---|---| | ≤ 1 | 14 | — | | 1 – 1.5 | 15 | — | | 1.5 – 2 | 16 | — | | 2 – 2.5 | 17 | — | | 2.5 – 3 | 18 | — | | 3 – 40 | — | 22 | | 40 – 63 | — | 21 | | 63 – 100 | — | 20 | | 100 – 150 | — | 18 | | 150 – 250 | — | 17 | By thickness**no delivery state stated** source `caishuku` | Thickness mm | Rm N/mm² | Re N/mm² | A% | |---|---|---|---| | ≤ 16 | 470 – 630 | ≥ 345 | ≥ 20 | | 16 – 40 | 470 – 630 | ≥ 335 | ≥ 20 | | 40 – 63 | 470 – 630 | ≥ 325 | ≥ 19 | | 63 – 80 | 470 – 630 | ≥ 315 | ≥ 19 | | 80 – 100 | 470 – 630 | ≥ 305 | ≥ 19 | | 100 – 150 | 450 – 600 | ≥ 285 | ≥ 18 | | 150 – 200 | 450 – 600 | ≥ 275 | ≥ 17 | | 200 – 250 | 450 – 600 | ≥ 265 | ≥ 17 | 3 further values are held for this grade under a condition the source did not name — a bound with no quantity attached. They are withheld rather than shown against a guessed condition. 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. [S320GP 1.0046 Mn ≤1,60 · Si ≤0,55 - ΔMn 0.00 - ΔSi 0.00 - 3 designations](/materials/din-en/s320gp "S320GP")[S355GP 1.0083 Mn ≤1,60 · Si ≤0,55 - ΔMn 0.00 - ΔSi 0.00 - 5 designations](/materials/din-en/s355gp "S355GP")[P235G1T1 1.0253 Mn ≤1,60 · Si ≤0,55 - ΔMn 0.00 - ΔSi 0.00 - 3 designations](/materials/din-en/p235g1t1 "P235G1T1")[P275T1 1.0256 Mn ≤1,60 · Si ≤0,55 - ΔMn 0.00 - ΔSi 0.00 - 7 designations](/materials/din-en/p275t1 "P275T1")[E370 1.0261 Mn ≤1,60 · Si ≤0,55 - ΔMn 0.00 - ΔSi 0.00 - 2 designations](/materials/din-en/e370 "E370")[P355T1 1.0421 Mn ≤1,60 · Si ≤0,55 - ΔMn 0.00 - ΔSi 0.00 - 4 designations](/materials/din-en/p355t1 "P355T1") ## 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=8811cfee-ad48-489e-93c2-300d80648457&designation=f7cb533c-7ba9-4933-a974-f4e7c4289175 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/gb/50b.pdf "Datasheet as PDF")