Grades
Find your grade, or its equivalent
Most of our stock is ordered against GB grades. These pages map each one to the ASTM, EN and JIS designations you may be working to, and list the sizes actually on the ground today.
Grade guide
12 grades, 1,700+ sizes
Equivalents are the closest common comparison for sourcing. Mill certificates with actual heat values ship with every order.
20#
ASTM A106 Gr.B
Low-carbon workhorse grade. Weldable, easy to machine and forgiving in fabrication, which is why it is the most stocked grade in our yard. Used where strength requirements are moderate but consistency and availability matter.
465 sizes in stock
45#
AISI 1045
Medium-carbon grade that machines predictably and responds well to quench and temper. The default choice when a part needs more strength than 20# can give but does not justify an alloy grade.
438 sizes in stock
42CrMo
AISI 4140
The chromium-molybdenum grade most heavy-duty machined parts are built from. As-rolled and quenched-and-tempered 42CrMo behave like two different materials — yield strength can differ by a factor of three — so the delivery condition matters more than the grade name.
289 sizes in stock
27SiMn
Comparable in use to EN E355 / ST52 honed tube
The silicon-manganese grade Chinese cylinder builders standardise on. Higher strength than 20# or 45# at the same wall, with a grain structure that hones cleanly — which is why it dominates cylinder tube applications rather than general machining.
155 sizes in stock
Q345B
EN S355JR
Low-alloy high-strength structural grade — the Chinese counterpart to S355. Where it becomes interesting is heat treatment: Q345B can be quenched and tempered up to Q420, Q460 and beyond, letting you buy one stocked grade and specify the strength you actually need.
133 sizes in stock
Q355B
EN S355JR
The current GB designation that replaced Q345B. Same structural role and near-identical mechanical envelope — if your drawing calls for either, we can usually supply from the same stock, confirmed against the mill certificate.
31 sizes in stock
30CrMnSiA
Russian 30KhGSA
A chromium-manganese-silicon grade used where strength-to-weight matters and 42CrMo is not quite enough. Common in aerospace-adjacent and high-load structural work; demands controlled heat treatment to reach its properties.
68 sizes in stock
12Cr1MoV Boiler Tube
Comparable service to ASTM A335 P12 / P11 range
Chromium-molybdenum-vanadium grade for sustained high-temperature service. Specified for power plant and boiler pressure parts where creep strength over decades governs the design rather than room-temperature strength.
— sizes in stock
15CrMo
ASTM A335 P12
Chromium-molybdenum grade for elevated-temperature pressure service. The workhorse of boiler and refinery piping below the P22 range, with good weldability for field construction.
38 sizes in stock
40Cr
AISI 5140
Chromium alloy grade for parts that need better hardenability than 45# without the cost of a molybdenum addition. Machines cleanly in the annealed condition and hardens predictably.
9 sizes in stock
30CrMo
AISI 4130
The weldable chromium-molybdenum grade. Lower carbon than 42CrMo, which trades some ultimate strength for markedly better weldability — the usual choice when the part is fabricated rather than machined from solid.
8 sizes in stock
L245
API 5L Gr.B
Line pipe grade for fluid transmission. We hold it in the large-diameter heavy-wall end of the range, where it overlaps with the structural and machining work that is our main business.
19 sizes in stock
Working to a grade that isn't listed?
Send the designation and the standard it comes from — we'll tell you what we hold that meets it, or source it.