Material number G10180: 1018
G10180 is the Unified Numbering System designation for 1018, low-carbon steel, cold-finished bar (case-hardenable) specified in ASTM A29.
What G10180 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 G10180 appears in several ASTM specifications (plate, bar, pipe) with different mechanical requirements.
1018 at a glance
AISI 1018 is the general-purpose low-carbon steel of North American machine shops: 0.15–0.20 % carbon and 0.6–0.9 % manganese, UNS G10180, sold overwhelmingly as cold-drawn bar ('1018 CRS') in rounds, squares, hexes and flats with a smooth, close-tolerance surface. Cold drawing raises the yield from about 220 MPa (hot-rolled) to 350–400 MPa and gives a bright finish that often needs no further machining — which is why 1018 is the default for shafts, spacers, pins, keys, fixtures, brackets and prototype parts that will not be heat-treated.
Its other role is case hardening: the low carbon core stays tough while carburizing produces a 58–62 HRC skin, so 1018 is used for pins, gears and cam followers in light service. Through-hardening is not possible. Weldability is excellent (CE ≈ 0.3) and it forms, bends and machines easily, though the low carbon makes it 'gummy' with built-up edge on tools.
There is no exact EN grade: C15 (lower Mn) is the case-hardening match, S235JRC or C22 the bright-bar substitute; JIS S17C/S20C, GB 20 and BS 080A17 are near or identical. When a drawing says 1018 for a plate, the buyer usually receives A36 or A1011 CS.
Full data sheet for 1018 → · Equivalent grades →