Why Grade Equivalence Matters When You Import Cold Drawn Steel

If your drawing or specification says S235JR, A36, SS400 or Q235B, you are actually talking about the same general-purpose carbon structural steel family. The grade names are different because China, Europe, Japan and the United States each write their own standards. When you order cold drawn bar from a Chinese mill, the grade on your PO has to match what the mill can produce under its own national standard, or you waste time on back-and-forth emails trying to confirm whether "equivalent" really means equivalent.

This page maps the cold drawn steel grades we actually stock and draw, side by side across GB (China), EN (Europe), JIS (Japan/Korea) and ASTM (USA). Use it to translate the grade on your drawing into the grade we draw, and to understand where the cross-standard match is close and where it is only approximate.

Cold Drawn Steel Grade Equivalence Table

Note: Equivalence is by chemical composition and mechanical property range. Cross-standard matches are close, not identical — see notes below.

How to Read This Table

The grade names on different standards are not exact copies. When a customer sends a drawing that says S355J2, we draw Q355ND, and the MTC lists both grades side by side so the buyer's inspection team can compare the actual chemistry and mechanical results against the standard they hold. In most structural and general machining applications, the cross-standard grade performs the same. There are three cases where "equivalent" needs a second look.

First, impact testing temperature. S355JR is tested at room temperature (20°C), S355J2 at -20°C, and S355K2 at -20°C with higher energy. Q355B matches the JR level, Q355ND matches J2. If your project is outdoors in a cold climate, do not accept Q355B when the drawing says J2 — the impact values are not the same.

Second, deoxidation practice. A36 and Q235B are both killed or semi-killed carbon steel, but A36 has a narrower silicon range and tighter manganese-to-carbon ratio. For welded structural parts the difference is negligible; for pressure-containing parts or codes that call out A36 specifically, we can confirm the heat chemistry before production.

Third, alloy grades for hardening. 4140 and 42CrMo4 are close but not identical: 42CrMo4 has slightly higher molybdenum and chromium on the upper end. For through-hardened pins and shafts at 28-38 HRC, both work. For surface-hardened gears with a strict case depth, the grade on the PO should match the grade the heat treater expects.

Which Grade Goes With Which Section

Not every grade is drawn in every section. The stock range and custom range split like this:

• Round bar (Ø5–100 mm): Q235B, Q355B, 45#, 40Cr, 42CrMo, free-cutting 12L14 equivalent. We draw round bar in the widest grade range because it is the most common machining stock.

• Flat bar (3–40 mm thick × 20–200 mm wide): Q235B, Q275, Q355B, 45#, 65Mn. Flat bar in spring steel (65Mn) is a regular order because of strip and clip applications.

• Square bar (4×4–120×120 mm): Q235B, Q355B, 45#, 40Cr, 42CrMo. Higher-alloy square bar is usually for construction machinery pins and wear blocks.

• Hex bar (S5–80 mm): Q235B, 45#, free-cutting steel. Hex bar goes mostly into fasteners and wrench flats, so free-machining grades are common.

• Custom special sections: C45/45# is the default for drawn profiles, with Q235B and Q355B on request. Non-standard sections are drawn to customer drawings after die feasibility review.

What the MTC Shows

Every commercial order carries a Mill Test Certificate to EN 10204 3.1. The MTC lists the heat number, the grade as ordered, and the actual measured values for carbon, manganese, silicon, sulfur, phosphorus, tensile strength, yield strength, elongation and hardness where applicable. If your PO specifies an EN or ASTM grade, we list the GB grade we drew on and the equivalent international grade, so your QA team can verify both.

For third-party inspection (SGS, BV, Intertek), we arrange witnessing at our mill before container loading. The inspector measures dimensions, checks surface, and witnesses the mechanical tests on samples from the same heat.

Common Questions on Grade Equivalence

Can you draw the exact grade on my drawing, or only the equivalent? For standard international grades we can source billet rolled to that specific standard where the tonnage justifies it. For most commercial orders, we draw the equivalent Chinese grade and certify it against the international standard you specify, with both grades on the MTC.

Is 1045 the same as C45? Yes, within normal commercial tolerances. Both are medium-carbon steel at about 0.45% C. The difference is in impurity limits and hardenability bands, which matter only for specific quenched-and-tempered components.

Do I need to specify a Japanese grade for Japanese customers? If the end customer is in Japan and their drawing says S45C, we draw 45# and certify the chemistry and mechanical properties against the JIS standard. The Japanese trading house receiving the bar compares the MTC values against JIS G4105 or G4051.

What if my drawing mixes grades? We draw multiple grades in one container all the time. Just list the section, grade and quantity for each item on the PO, and we consolidate them on the mill.

Need Help Matching Your Drawing Grade?

Send us your drawing or PO and we will confirm the equivalent grade, achievable section size, and lead time. If the grade on your drawing is outside our standard stock range, we source the billet from nearby mills and draw it to order. We reply within one working day with grade confirmation and a quotation.

Cold Drawn vs Hot Rolled Grade Performance

The grade equivalence table above applies to both hot rolled and cold drawn bar, but cold drawing changes the mechanical properties in a way buyers should understand. When a bar is pulled through a die at room temperature, the surface layer work-hardens: tensile strength goes up, elongation goes down, and the surface hardness rises. The core of the bar stays in the hot rolled condition.

For Q235B round bar at 20 mm diameter, hot rolled yield is about 235 MPa. After cold drawing with a typical 15-20% reduction, the measured yield on the drawn bar often reads 280-320 MPa, and tensile strength climbs from 400 MPa to 450-500 MPa. Elongation drops from 26% to around 20-22%. This is normal and expected. If your design uses the hot rolled minimum values, the drawn bar actually exceeds them. If your design assumes annealed ductility for bending or forming, order the bar in annealed (SR) condition instead of as-drawn (BK).

For alloy grades like 42CrMo, the cold drawn condition is the machining blank. The part is machined from drawn bar, then quenched and tempered to the final hardness. The drawing reduction does not change the final heat treated properties; it only makes the bar easier to machine to size before hardening.

Delivery Conditions: BK, SR and What They Mean

When you order cold drawn bar, the delivery condition on the PO matters as much as the grade. Three conditions cover most orders:

• BK (cold drawn, as drawn): the bar is drawn straight to size and shipped. Surface is bright and scale-free, strength is at the work-hardened level. This is the default for most machining stock.

• SR (annealed / soft annealed): after drawing, the bar is annealed to relieve residual stress and soften the surface. Use this if you need to bend, form, or machine deep pockets where residual stress would cause movement.

• QT (quenched and tempered): we draw to size, then quench and temper to your specified hardness (typically 28-38 HRC for 42CrMo pins). This is ordered when the part is small enough to harden uniformly and the customer does not have heat treat equipment.

If you are not sure which condition to order, tell us what you do with the bar after it arrives. If you turn it on a lathe and weld it, BK is fine. If you bend it or machine large asymmetric cuts, SR is safer. If you are ordering finished pins ready to install, QT may save you a step.

Why We Do Not Promise Exact Grade Matches on Everything

Some suppliers will tell you "we can supply any standard" and then draw whatever billet they have in stock and stamp the grade you asked for. That is not how we work. If your PO says 4140 and the billet we have is 42CrMo (close but not identical), we tell you before we draw it, and you decide whether the chemistry difference is acceptable for your part. If it is not, we source the correct billet and adjust the lead time.

This matters most for parts that go into pressure systems, lifting equipment, or any component where a failure causes injury. For general structural brackets and machine bases, the equivalent grade is fine and the MTC confirms the actual chemistry. For safety-critical parts, the grade on the PO should match the grade on the MTC exactly, and we will not substitute without asking.