A2 tool steel equivalents

A2 tool steel is nearest to EN 1.2363 (X100CrMoV5), JIS SKD12 and China GB Cr5Mo1V. These are nearest equivalents, not identical grades: the governing standard or mill certificate decides.

Designations follow EN 10027 and ISO 4957. Updated 6 October 2026.

EN steel number for A2

1.2363

X100CrMoV5 · SKD12 · Cr5Mo1V

A2 = EN 1.2363 X100CrMoV5 = JIS SKD12 = GB Cr5Mo1V

AISI / ASTM / SAE US: A2
EN steel number EN 10027-2: 1.2363
EN steel name EN 10027-1: X100CrMoV5
JIS Japan: SKD12
GB China: Cr5Mo1V
Family: Cold-work tool steel, air-hardening

Nearest-equivalent designationsCheck the mill certificate

About A2

Cold-work tool steel, air-hardening. General characteristics; check the standard and the supplier for anything critical.

What it is

An air-hardening cold-work tool steel. It moves less in hardening than oil-hardening grades and balances wear resistance and toughness: tougher than D2, more wear resistant than O1.

Typical uses

Punches, blanking and forming dies, trim dies, gauges and machine knives.

Machining notes

Machine annealed; easier than D2. Finish by grinding after hardening.

Related grades

Grades people often compare with this one.

D2 tool steelMore wear resistant, less tough1.2379 · SKD11 · Cr12Mo1V1 O1 tool steelOil-hardening, easiest to heat treat1.2510 · SKS3 · 9CrWMn

Drilling and tapping

Tap drills

Drill and tap hardenable tool steel in the annealed condition, before heat treatment. A slightly larger tap drill, around 60–70 % thread, eases the load on the tap.

Tap drill chart

Drill sizes

Number, letter and fractional drill sizes with metric equivalents, for dowel, clearance and pilot holes in tooling.

Drill size chart

All tool steel grades

Nearest equivalents across the five designation systems.

Tool steel grade equivalents
AISI / ASTM	EN name	EN number	JIS	China GB
D2	X153CrMoV12	1.2379	SKD11	Cr12Mo1V1
H13	X40CrMoV5-1	1.2344	SKD61	4Cr5MoSiV1
O1	100MnCrW4	1.2510	SKS3	9CrWMn
A2	X100CrMoV5	1.2363	SKD12	Cr5Mo1V
M2	HS6-5-2	1.3343	SKH51	W6Mo5Cr4V2
P20	40CrMnMo7	1.2311	—	3Cr2Mo

Equivalents are nearest matches, not identical grades. Composition limits, mechanical properties and test requirements differ in detail between standards and product forms. For anything that matters, the governing standard, the drawing and the mill certificate decide.

Common questions

What is the European equivalent of A2 tool steel?

The nearest EN grade is 1.2363, steel name X100CrMoV5.

What is the JIS equivalent of A2 tool steel?

The nearest Japanese grade is SKD12.

What is the Chinese GB equivalent of A2 tool steel?

The nearest Chinese GB grade is Cr5Mo1V.

Is 1.2363 the same as A2?

1.2363 (X100CrMoV5) is the nearest European equivalent of A2, not an identical grade. Composition limits and required properties differ in detail, so check the governing standard or the mill certificate when it matters.

What is A2 used for?

Punches, blanking and forming dies, trim dies, gauges and machine knives.