--- title: "EX4 — Case hardening steels" description: "EX4 in AISI / SAE: material number 1.7321, also listed as 20MoCr4. Category: Case hardening steels. Designations recorded for this grade: 9." canonical: https://steelequivalents.com/materials/aisi-sae/ex4 language: en robots: index, follow og_type: website type: material-detail language_alternates: en: https://steelequivalents.com/materials/aisi-sae/ex4.md cs: https://steelequivalents.com/cs/materiály/aisi-sae/ex4.md de: https://steelequivalents.com/de/werkstoffe/aisi-sae/ex4.md es: https://steelequivalents.com/es/materiales/aisi-sae/ex4.md fr: https://steelequivalents.com/fr/matériaux/aisi-sae/ex4.md hu: https://steelequivalents.com/hu/anyagok/aisi-sae/ex4.md it: https://steelequivalents.com/it/materiali/aisi-sae/ex4.md nl: https://steelequivalents.com/nl/materialen/aisi-sae/ex4.md pl: https://steelequivalents.com/pl/materiały/aisi-sae/ex4.md pt: https://steelequivalents.com/pt/materiais/aisi-sae/ex4.md ru: https://steelequivalents.com/ru/материалы/aisi-sae/ex4.md tr: https://steelequivalents.com/tr/malzemeler/aisi-sae/ex4.md zh: https://steelequivalents.com/zh/材料/aisi-sae/ex4.md ja: https://steelequivalents.com/ja/材料/aisi-sae/ex4.md ar: https://steelequivalents.com/ar/المواد/aisi-sae/ex4.md ko: https://steelequivalents.com/ko/재료/aisi-sae/ex4.md pt-br: https://steelequivalents.com/pt-br/materiais/aisi-sae/ex4.md hi: https://steelequivalents.com/hi/सामग्री/aisi-sae/ex4.md content_hash: sha256:d6b0375b3c860769c49058f283a0c846fbb2806031b2349000321652892547cb 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/aisi-sae/ex4 > Canonical URL: https://steelequivalents.com/materials/aisi-sae/ex4 > 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. AISI / SAE · United States · 9 designations # EX4 EX4 is a designation in AISI / SAE for the material held under material number 1.7321, also listed as 20MoCr4. It is a material in the category Case hardening steels. We list 9 designations recorded for this grade, in the standards DIN / EN, UNS, AISI / SAE, UNE and SRPS. - [*Material no.* **1.7321**](/materials/material-no/1.7321 "Material no.: 1.7321") - [*Category* **Case hardening steels · 60 grades**](/categories/case-hardening-steels "Category: Case hardening steels · 60 grades") - *Designations* **9** [Search](/search "Steel grade search")[Inquiry](/inquiry?material=2cd53be0-f9b8-42b1-9fcb-4befa86b1da0&designation=001de1bb-2178-4250-a996-44b4beaacb91 "Inquiry")[**Datasheet as PDF** Print-ready A4 document **Generating …** **Download started** **Try again**](/materials/aisi-sae/ex4.pdf "Datasheet as PDF") ## If you came for one of these The most-used names for this grade. - [DIN / EN 20MoCr4 This grade’s own name](/materials/din-en/20mocr4 "DIN / EN 20MoCr4") - [UNS G41180 This grade’s own name](/materials/uns/g41180 "UNS G41180") - [AISI / SAE 4118 This grade’s own name · 2 grades on that route](/materials/aisi-sae/4118 "AISI / SAE 4118") ## About Case hardening steels Case hardening steels are steels designed to develop a hard, wear-resistant surface while retaining a tough and ductile core. They are used for components such as gears, shafts and other machine parts exposed to contact wear and cyclic loading. This describes the material class as a whole. Always confirm the individual grade against the standard before ordering. ## Also known as 9 designations · 5 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 · 1 - [20MoCr4 This grade’s own name](/materials/din-en/20mocr4 "DIN / EN 20MoCr4") UNS United States · 2 - [G41180 This grade’s own name](/materials/uns/g41180 "UNS G41180") - [H41180 This grade’s own name](/materials/uns/h41180 "UNS H41180") AISI / SAE United States · 4 - [4118 This grade’s own name](/materials/aisi-sae/4118 "AISI / SAE 4118") - [4118H This grade’s own name](/materials/aisi-sae/4118h "AISI / SAE 4118H") - [4118RH This grade’s own name](/materials/aisi-sae/4118rh "AISI / SAE 4118RH") - **EX4 This grade’s own name** UNE Spain · 1 - [20MoCr5 Indicative](/materials/une/20mocr5 "UNE 20MoCr5") SRPS Serbia · 1 - [Č.7420 Indicative](/materials/srps/c-7420 "SRPS Č.7420") 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 Mo Cr Iron — the balance, never listed by a standard — 97.6 % Mn — 0.9 % Mo — 0.5 % Cr — 0.4 % Traces & impurities · 0.7 % Logarithmic scale, 0.01 % to 100 % — every value here compares directly, decade by decade. | Element | % by weight | |---|---| | C | 0.17–0.23 | | Si | ≤ 0.4 | | Mn | 0.7–1 | | P | 0.025 | | S | 0.035 | | Cr | 0.3–0.6 | | Mo | 0.4–0.5 | Carbon Silicon Manganese Phosphorus Sulfur Chromium Molybdenum 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 | 0,17-0,23 | 0.170 | 0.230 | Range | | Si | ≤0,40 | — | 0.400 | Max | | P | 0,025 | 0.025 | 0.025 | Exact | | S | 0,035 | 0.035 | 0.035 | Exact | | Cr | 0,30-0,60 | 0.300 | 0.600 | Range | | Mn | 0,70-1,00 | 0.700 | 1.000 | Range | | Mo | 0,40-0,50 | 0.400 | 0.500 | 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. ## Physical & mechanical properties Density 7,76 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 4 conditions · 4 values By delivery state**Treated to improve shearability** source `steelnumber` | Delivery state | HB | |---|---| | Treated to improve shearability | 255 | By delivery state**Soft annealed** source `steelnumber` | Delivery state | HB | |---|---| | Soft annealed | 207 | By delivery state**Treated to hardness range** source `steelnumber` | Delivery state | HB | |---|---| | Treated to hardness range | 156 – 207 | By delivery state**Treated to ferrite-pearlite structure and hardness range** source `steelnumber` | Delivery state | HB | |---|---| | Treated to ferrite-pearlite structure and hardness range | 140 – 187 | 4 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. ## Heat treatment Supply condition - Annealing - Spheroidize annealing - Spheroidize annealing - Spheroidize annealing - Soft annealing All product forms - Soft annealing All product forms - Quenching and tempering Bar and Wire 2\