Material number G10450: 1045
G10450 is the Unified Numbering System designation for 1045, medium-carbon steel, hardenable specified in ASTM A29.
What G10450 means
UNS numbers (ASTM E527 / SAE J1086) use a letter for the alloy family and five digits: G = AISI/SAE carbon and alloy steels (G41400 = 4140), S = stainless and heat-resisting steels (S30400 = 304), K = miscellaneous steels (K02600 = A36), T = tool steels, N = nickel alloys. The UNS number identifies a composition, not a product form or property level, so G10450 appears in several ASTM specifications (plate, bar, pipe) with different mechanical requirements.
1045 at a glance
AISI 1045 is the medium-carbon workhorse: 0.43–0.50 % carbon, 0.6–0.9 % manganese, no alloying, UNS G10450 — the American twin of EN C45, JIS S45C and GB/GOST 45. It is the cheapest steel that can be usefully hardened: through-hardening in water works up to about 20–25 mm, and flame or induction hardening gives a 55–58 HRC wear surface on shafts, gears and rollers of any size while the core stays at ~180 HB. Most 1045 is used either as-rolled/cold-drawn for shafting, or surface-hardened.
Cold-drawn 1045 bar reaches roughly 530 MPa yield and 625 MPa tensile — about 40 % above 1018 — and it is the standard material for turned-ground-and-polished (TGP) and induction-hardened chrome-plated shafting used in linear bearings and hydraulic cylinders. Normalized or Q&T it serves for axles, bolts (SAE Grade 5), crankshafts in small engines, spindles, gears, sprockets and machine parts of moderate size.
The price of the higher carbon is weldability: 1045 needs 200–300 °C preheat and post-weld tempering, and it is more prone to quench cracking than 1040. Machinability is still good (≈ 55–60 %).
Full data sheet for 1045 → · Equivalent grades →