Is 42CrMo4 the same as B7?

Same steel family, not the same standard. Both are quenched and tempered Cr-Mo steel with almost the same strength up to M64, but the tests, the limits and the certificate differ.

Can I use 42CrMo4 where B7 is specified?

Only with written approval from whoever owns the specification. The certificate states the standard the parts were tested to; a 42CrMo4 certificate does not show B7 compliance, and the other way round.

Can one stud be certified to both?

Only if the heat and the tests meet both standards – the chemistry and hardness of ASTM A193 and the tensile range and impact test of EN 10269. Ask for it in your enquiry.

The EN material number of 42CrMo4. Both names refer to the same steel.

Which certificate comes with the bolts?

EN 10204 3.1 as standard, with the heat number marked on the parts. 3.2 with a third-party inspector on request – see our certificate guide.

Do you supply both from stock?

Yes. Hex bolts in B7 and 42CrMo4 are shipped from stock, plain or coated. Studs in both grades are cut, chamfered and marked in-house.

Technical guide

42CrMo4 or ASTM A193 B7 – what is the difference?

42CrMo4 (1.7225) and ASTM A193 B7 are the same kind of steel: a quenched and tempered chromium-molybdenum alloy with almost the same strength up to M64. The difference is the standard. EN 10269 adds an upper tensile limit and an impact test, ASTM A193 a maximum hardness and no impact test – so use the grade your specification names.

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Short answer

Same steel family – Both are quenched and tempered Cr-Mo steel; the chemistries overlap.
Different standard – B7 to ASTM A193 for ASME projects, 42CrMo4 to EN 10269 for European pressure equipment.
Strength – Up to M64: B7 min. 860 MPa tensile and 720 MPa yield, 42CrMo4 860–1 060 MPa and min. 730 MPa.
Impact test – 42CrMo4 to EN 10269 needs min. 50 J at +20 °C; B7 has no impact test.
Substitution – Only with approval of whoever owns the specification – the certificate names one standard.

Comparison

Side by side, up to M64.

Values at room temperature. B7 up to 2½" (M64); 42CrMo4 up to 65 mm (EN 10269:2013, 60 mm in the 2001 edition). Larger diameters have lower values – see the standard.

Property	ASTM A193 B7	EN 10269 42CrMo4 (1.7225) +QT
Steel	Cr-Mo alloy steel (AISI 4140 / 4142 type), quenched and tempered	Cr-Mo alloy steel, quenched and tempered
Tensile strength Rm	min. 860 MPa (125 ksi)	860–1 060 MPa
Yield strength Rp0.2	min. 720 MPa (105 ksi)	min. 730 MPa
Elongation	min. 16 %	min. 14 %
Reduction of area	min. 50 %	min. 50 %
Hardness	max. 321 HBW / 35 HRC	–
Impact test	Not required	KV2 min. 50 J at +20 °C
Tempering temperature	min. 593 °C (1 100 °F)	–
Larger diameters	Over 2½" to 4": 115 / 95 ksi; over 4" to 7": 100 / 75 ksi	Lower values above 65 mm

Chemistry

The chemistries overlap.

Heat analysis in % by mass. For B7 bars over 3½" the carbon may be up to 0.50 %.

Element	ASTM A193 B7	EN 10269 42CrMo4
C	0.37–0.49	0.38–0.45
Mn	0.65–1.10	0.60–0.90
Si	0.15–0.35	≤ 0.40
P	≤ 0.035	≤ 0.025
S	≤ 0.040	≤ 0.035
Cr	0.75–1.20	0.90–1.20
Mo	0.15–0.25	0.15–0.30

How to choose

Four questions decide the grade.

01Which standard does the specification name?ASME and ASTM projects call for B7 with A194 2H nuts. European pressure equipment and DIN 2510 flange bolting call for 42CrMo4 to EN 10269. Supply what the drawing names.
02Is an impact test required?42CrMo4 to EN 10269 is Charpy-tested at +20 °C. B7 is not. For low-temperature service in the ASTM world, specify A320 L7 – see our stud bolt grade guide.
03Is there an upper strength limit?EN 10269 caps the tensile strength of 42CrMo4 at 1 060 MPa; ASTM A193 caps B7 at 321 HBW / 35 HRC. Where H₂S demands a lower hardness, neither fits – use B7M with 2HM nuts.
04Is the diameter above M64?Both standards lower the minimum values for larger diameters: B7 above 2½", 42CrMo4 above 65 mm. Check the table in the standard for the size you need.

FAQ

Questions we get every week.

Is 42CrMo4 the same as B7?: Same steel family, not the same standard. Both are quenched and tempered Cr-Mo steel with almost the same strength up to M64, but the tests, the limits and the certificate differ.
Can I use 42CrMo4 where B7 is specified?: Only with written approval from whoever owns the specification. The certificate states the standard the parts were tested to; a 42CrMo4 certificate does not show B7 compliance, and the other way round.
Can one stud be certified to both?: Only if the heat and the tests meet both standards – the chemistry and hardness of ASTM A193 and the tensile range and impact test of EN 10269. Ask for it in your enquiry.
What is 1.7225?: The EN material number of 42CrMo4. Both names refer to the same steel.
Which certificate comes with the bolts?: EN 10204 3.1 as standard, with the heat number marked on the parts. 3.2 with a third-party inspector on request – see our certificate guide.
Do you supply both from stock?: Yes. Hex bolts in B7 and 42CrMo4 are shipped from stock, plain or coated. Studs in both grades are cut, chamfered and marked in-house.

Next step

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Reviewed November 2026 by HBS Solutions. Based on ASTM A193/A193M and EN 10269:2013. Values are minimums from the standard unless a range is given; always check the edition and options named in your project specification.

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