EN 10083-3 — Steels for quenching and tempering. Part 3: Technical delivery conditions for alloy steels
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Scope
Alloy steels for quenching and tempering: Mn, Cr, CrMo, CrNiMo, MnCr, MnB grades such as 42CrMo4, 34CrNiMo6, 25CrMo4, 41Cr4, 30MnB5, 51CrV4, 36NiCrMo16. Gives chemistry, hardenability bands (+H, +HH, +HL), mechanical properties in +QT by ruling section, and impact values.
Grades covered by EN 10083-3
| Grade | No. | Type | C % | Yield MPa | Tensile MPa | Nearest equivalents |
|---|---|---|---|---|---|---|
| 42CrMo4 | 1.7225 | Chromium-molybdenum steel for quenching and tempering | 0.38 – 0.45 | 900 | 1100–1300 | 4140, 4142, SCM440 |
Revision history and superseded standards
| Year | Change |
|---|---|
| 1991 | EN 10083-1:1991 — alloy Q&T grades in Part 1 |
| 2006 | EN 10083-3:2006 — alloy grades moved to Part 3; current |
Supersedes: DIN 17200:1987 (alloy grades); EN 10083-1:1991 (alloy grades).
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Related standards
Alloying buys section size, not headline strength
Part 3 covers the alloy quenching and tempering steels: 25CrMo4, 42CrMo4, 34CrNiMo6, 51CrV4 and their relatives. Their tensile bands overlap heavily with the non-alloy grades of part 2, which makes the reason for their existence easy to miss.
What the chromium, molybdenum and nickel buy is hardenability — the depth to which a quench transforms the structure. A 42CrMo4 shaft of 100 mm diameter reaches its specified properties in the core; a C45 shaft of the same size does not, whatever the surface hardness reads. Alloy grades are bought by section size and by the toughness that survives tempering, not by the number on the tensile certificate.
Reading the alloy designation
The name is arithmetic. 42CrMo4 is 0.42 % carbon — the leading number divided by 100 — with chromium and molybdenum listed in descending order, and the final 4 meaning about 1 % chromium after the standard divisor is applied. 34CrNiMo6 is 0.34 % carbon with chromium, nickel and molybdenum, the 6 indicating roughly 1.5 % chromium.
The S suffix, as in 42CrMoS4, adds controlled sulphur for machining. The delivery condition — normally +QT — belongs on the order beside the grade, because the grade describes a chemistry and the condition describes a part.