Short answer: EN19 is a 1% chromium, 0.2–0.3% molybdenum alloy steel with about 0.4% carbon. Its current BS 970 code is 709M40, the European name is 42CrMo4 (material no. 1.7225), the American is AISI / SAE 4140 and the Japanese is SCM440. The Indian Standard equivalent is 40Cr4Mo3. In India the bar is usually ordered as EN19 or 4140.
In this guide: Equivalents · Chemistry compared · Are they interchangeable? · Strength and EN19T · EN19 and A193 B7 · EN19 or EN24? · FAQ
EN19 / 42CrMo4 equivalent grades
| Standard | Designation | Note |
|---|---|---|
| BS 970 (old) | EN19 | The most common name in the Indian market |
| BS 970 (current) | 709M40 | 708M40 is a near twin with less molybdenum |
| EN 10083-3 (Europe) | 42CrMo4 / 1.7225 | Also seen as 42CrMoS4 (1.7227) with added sulphur for machining |
| AISI / SAE (USA) | 4140 | 4142 and 4145 are the same family with more carbon |
| JIS (Japan) | SCM440 | JIS G4053 |
| IS (India) | 40Cr4Mo3 | Indian Standard name |
| GB (China) | 42CrMo | Common on imported bar and forgings |
All of these are the same steel family. See our equivalent grades chart for EN24, EN47, EN36C, EN353 and SAE 8620 on the same basis, and BS 970 codes explained for what 709M40 means.
Chemical composition compared
| Element, % | 709M40 (EN19) | 42CrMo4 | AISI 4140 | SCM440 | IS 40Cr4Mo3 |
|---|---|---|---|---|---|
| Carbon (C) | 0.36–0.44 | 0.38–0.45 | 0.38–0.43 | 0.38–0.43 | 0.35–0.45 |
| Silicon (Si) | 0.10–0.35 | max 0.40 | 0.15–0.35 | 0.15–0.35 | 0.10–0.35 |
| Manganese (Mn) | 0.70–1.00 | 0.60–0.90 | 0.75–1.00 | 0.60–0.90 | 0.50–0.80 |
| Chromium (Cr) | 0.90–1.20 | 0.90–1.20 | 0.80–1.10 | 0.90–1.20 | 0.90–1.20 |
| Molybdenum (Mo) | 0.25–0.35 | 0.15–0.30 | 0.15–0.25 | 0.15–0.30 | 0.20–0.35 |
Typical limits as published for each standard; phosphorus and sulphur limits (generally 0.025–0.040% max) vary between them. A mill's own range can also differ slightly from any one standard, so always compare the mill test certificate with the standard named on your drawing.
Are EN19, 42CrMo4 and 4140 interchangeable?
For most machined and heat-treated parts, yes. The carbon, chromium and molybdenum overlap closely, so all of them respond to hardening and tempering in the same way. The differences are in the edges of the ranges:
- AISI 4140 allows more manganese and slightly less chromium and molybdenum than 42CrMo4.
- 709M40 asks for more molybdenum (0.25–0.35%) than 42CrMo4 or 4140, which helps it keep strength in thicker sections and resist temper softening.
- IS 40Cr4Mo3 sits close to 709M40 on molybdenum but allows lower manganese.
If a drawing names one standard specifically, for example 42CrMo4 to EN 10083-3 for an export job, order to that standard and check the certificate. Our mill test certificate guide shows what to look for.
Strength after hardening, and what EN19T means
Like every through-hardening steel, EN19 loses strength as the bar gets thicker, because the centre cools more slowly in the quench. Typical hardened and tempered values for 42CrMo4 (EN 10083-3):
| Bar diameter | Tensile strength, MPa | Yield, MPa min |
|---|---|---|
| up to 16 mm | 1100–1300 | 900 |
| 16–40 mm | 1000–1200 | 750 |
| 40–100 mm | 900–1100 | 650 |
| 100–160 mm | 800–950 | 550 |
| 160–250 mm | 750–900 | 500 |
EN19T is EN19 hardened and tempered to BS 970 condition T: 850–1000 MPa tensile, roughly 248–302 HB (about 25–32 HRC). The letter is a strength band and means the same for any BS 970 grade; our EN24 vs EN24T guide explains the full T to Z system, and the hardness guide gives the HRC conversions.
EN19, 4140 and ASTM A193 B7
Buyers often ask for the Indian equivalent of SA / ASTM A193 B7. B7 is not a bar grade but a specification for high-temperature bolting: studs and bolts made from 4140, 4142 or 4145 type steel and quenched and tempered to:
- tensile strength at least 860 MPa (125 ksi) and yield at least 720 MPa (105 ksi), for diameters up to 64 mm (2½ in);
- hardness no more than 321 HB (35 HRC).
So EN19 / 42CrMo4 / 40Cr4Mo3 bar is the usual raw material for B7 parts in India, but the bar alone is not B7: the finished part must be heat treated and tested to A193. Larger diameters have lower minimums, so check the specification for your size.
EN19 or EN24?
EN19 is the economical choice for medium-duty shafts, gears, spindles, bolts and studs in small to medium sections. Step up to EN24 (817M40 / 4340) when the part is large in section, heavily or shock loaded, or must hold its strength right through a thick bar: the 1.5% nickel in EN24 lets it harden deeper and makes it tougher. Our EN24 vs EN19 vs EN8 comparison shows the strength by bar size side by side.
At Sai International we stock EN24 round bar Ø16–205 mm (annealed up to Ø100 mm, as-rolled above), along with EN47, EN36C, EN353 and SAE 8620, every dispatch with its mill test certificate. Minimum order is 100 kg.
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EN19 / 42CrMo4: frequently asked questions
What is the equivalent of 42CrMo4 in India?
The Indian Standard equivalent of 42CrMo4 (1.7225) is 40Cr4Mo3. In the Indian market the same steel is usually ordered as EN19, the old BS 970 name, or as AISI 4140.
Is EN19 the same as 42CrMo4 and AISI 4140?
They are close equivalents, not identical specifications. All three are about 0.4% carbon chromium-molybdenum steels and are interchangeable for most machined and heat-treated parts, but the limits differ slightly: AISI 4140 allows more manganese and less chromium, and BS 970 709M40 asks for more molybdenum than 42CrMo4. Check the chemistry on the mill test certificate against the standard on your drawing.
What is the equivalent of SCM440?
SCM440 is the Japanese (JIS G4053) name for the same chromium-molybdenum steel. Its equivalents are 42CrMo4 (1.7225), AISI 4140, EN19 / BS 970 709M40 and IS 40Cr4Mo3.
What is EN19T?
EN19T is EN19 hardened and tempered to BS 970 condition T, a tensile strength of 850–1000 MPa, roughly 248–302 HB. The letter is a strength band, not a different steel.
Is EN19 the same as ASTM A193 B7?
No. A193 B7 is a bolting specification, not a bar grade. B7 studs and bolts are made from 4140, 4142 or 4145 type chromium-molybdenum steel and must be quenched and tempered to at least 860 MPa tensile and 720 MPa yield (up to 64 mm), with a maximum hardness of 321 HB (35 HRC). EN19 / 42CrMo4 bar is commonly used to make B7 parts, but the finished part must be heat treated and tested to A193.
When should I use EN24 instead of EN19?
Choose EN24 (817M40 / 4340) when the part is large in section, heavily or shock loaded, or must hold strength right through a thick bar. The nickel in EN24 lets it harden deeper and makes it tougher than EN19 at the same strength.
Values are typical published limits for guidance and are not a guarantee; actual chemistry and properties depend on the heat, size and heat treatment. Please confirm suitability for your application.