GRADE GUIDE · 4140
AISI 4140 — 42CrMo4 in European naming — is the world's default medium-carbon alloy steel: chromium and molybdenum give it deep hardenability, and it is usually stocked quenched and tempered to about 28–32 HRC. Shafts, gears, bolts, spindles and machine parts are made from it every day.
Also listed as: 42CrMo4 · 1.7225 · EN19 / 708M40 · SCM440 (JIS)
Stock turns over piece by piece — what's listed is what exists. Post the spec you need and we match it against incoming material; you're alerted the moment something lands.
4140's appeal is a strength-toughness balance you can buy off the shelf: in the common Q&T condition it delivers roughly 650–900 MPa yield depending on section, already heat-treated, so most parts are machined to size and put straight to work. Pump shafts, drive couplings, hydraulic rods, high-tensile studs and die sets across every Gulf workshop trace back to this grade.
It answers to many names — 42CrMo4, 1.7225, EN19, 708M40, SCM440 — and certificates from different mills use different ones for the same steel. Off-cuts land here mostly as round bar ends from machine shops; check the certificate's delivery condition, since annealed and pre-hardened bar machine and perform very differently.
Practically yes — they are the American, European and old British designations of the same chrome-moly chemistry, with minor spec differences. Certificates commonly cite two or three of the names together.
With care: its carbon and alloy content demand preheat (typically 200–300 °C), low-hydrogen consumables and slow cooling, plus tempering afterward on critical parts. For heavily welded structures, plain S355 is the easier choice.
Pre-hardened (Q&T ~30 HRC) suits most shaft and machine-part work — machine it and it is finished. Annealed bar is for parts that will be through-hardened to higher levels after machining.