Alloy Steel 4145 / 4145 MOD in Bar, Hollow Bored Bar & Stabilisers

Specifications: Alloy 4145, AISI 4145, UNS G41450

Typically used in oil and gas applications, Castle Metals stock Alloy 4145 in round bar, hollow bored bar and Stabilizers, from their warehouse in Blackburn, UK.

4145 is available in sizes 3.25” – 24”, fully certified to API 7-1, quenched and tempered with hardness 30 to 36HRc. Stabilizers made specifically to requirements.

Alloy 4145 is used in a number of applications including drill collars, pup joints, subs and various other down hole tool products

Alloy 4145 is a Chrome / Moly alloy displaying high hardenability and good hardness penetration qualities. When heat treated, Alloy 4145 can be machined relatively effectively despite this well-known hardening grade maintaining its properties at very high temperatures! What makes Alloy 4145 harder than Alloy 4140 is the increased use of carbon applied to Alloy 4145.

Customers requiring even higher hardenability properties, particularly those operating within the Oil & Gas sector, may look to deploy Alloy 4145 MOD, as opposed to standard Alloy 4145, due to the increased amount of Mn, Cr or Mo used within to further strengthen the alloy.


Chemistry (range or maximum in %)

GRADE C Mn P Max S Si Ni Cr Mo
4145 .43/.48 .75/1.00 0.035 0.04 .15/.35 - .80/1.00 .15/.25
4145MOD .42/.49 .75/1.30 0.025 0.025 .15/.35 .25 Max .75/1.20 .15/.45

Grade 4145 Bars: Annealed / Normalized & Tempered Properties

4145 Rounds 1-1/2" - 9" Hot Rolled & Annealed ASTM A29/A322
4145MOD Rounds 3" - 11" Hot Rolled Quenched & Tempered 90-100-110-120-130 min Yields