17-4PH stainless steel equivalents

17-4PH stainless steel is nearest to EN 1.4542 (X5CrNiCuNb16-4), JIS SUS630 and China GB 05Cr17Ni4Cu4Nb. It is also known as type 630. These are nearest equivalents, not identical grades: the governing standard or mill certificate decides.

Designations follow EN 10027 and EN 10088-1. Updated 6 October 2026.

EN steel number for 17-4PH (630)

1.4542

X5CrNiCuNb16-4 · SUS630 · 05Cr17Ni4Cu4Nb

17-4PH (630) = EN 1.4542 X5CrNiCuNb16-4 = JIS SUS630 = GB 05Cr17Ni4Cu4Nb

AISI / ASTM / SAE US: 17-4PH (630)
EN steel number EN 10027-2: 1.4542
EN steel name EN 10027-1: X5CrNiCuNb16-4
JIS Japan: SUS630
GB China: 05Cr17Ni4Cu4Nb
Family: Precipitation-hardening stainless

Nearest-equivalent designationsCheck the mill certificate

About 17-4PH (630)

Precipitation-hardening stainless. General characteristics; check the standard and the supplier for anything critical.

What it is

A precipitation-hardening martensitic stainless steel containing copper. It is hardened by a low-temperature ageing treatment, identified by condition codes such as H900 and H1150, which gives high strength with little distortion.

Typical uses

Aerospace fittings, pump and valve shafts, gears, fasteners, and oil and gas components.

Machining notes

Usually machined in condition A (solution-treated) or an over-aged condition, then aged. Ageing causes only slight, predictable dimensional change.

Related grades

Grades people often compare with this one.

410 stainless steelConventional hardenable martensitic grade1.4006 · SUS410 · 12Cr13 420 stainless steelHigher-hardness martensitic grade1.4021 · SUS420J1 · 20Cr13

Fasteners and tapping

Stainless fasteners

Stainless bolts are graded to ISO 3506 (for example A2 and A4 austenitic), not to the ISO 898-1 classes in the bolt torque chart. Do not use those torque values for stainless fasteners; stainless threads also gall easily, so use an anti-seize and the fastener maker's figures.

Bolt torque chart

Tapping stainless

Stainless work-hardens and grips the tap. Aim for about 60–70 % thread: one size larger than the usual tap drill is common. The tap drill chart shows the percentage each drill leaves.

Tap drill chart

All stainless steel grades

Nearest equivalents across the five designation systems.

Stainless steel grade equivalents
AISI / ASTM	EN name	EN number	JIS	China GB
304	X5CrNi18-10	1.4301	SUS304	06Cr19Ni10
304L	X2CrNi18-9	1.4307	SUS304L	022Cr19Ni10
316	X5CrNiMo17-12-2	1.4401	SUS316	06Cr17Ni12Mo2
316L	X2CrNiMo17-12-2	1.4404	SUS316L	022Cr17Ni12Mo2
321	X6CrNiTi18-10	1.4541	SUS321	06Cr18Ni11Ti
303	X8CrNiS18-9	1.4305	SUS303	Y12Cr18Ni9
310S	X8CrNi25-21	1.4845	SUS310S	06Cr25Ni20
201	X12CrMnNiN17-7-5	1.4372	SUS201	12Cr17Mn6Ni5N
430	X6Cr17	1.4016	SUS430	10Cr17
410	X12Cr13	1.4006	SUS410	12Cr13
420	X20Cr13	1.4021	SUS420J1	20Cr13
440C	X105CrMo17	1.4125	SUS440C	108Cr17
17-4PH (630)	X5CrNiCuNb16-4	1.4542	SUS630	05Cr17Ni4Cu4Nb
2205 duplex	X2CrNiMoN22-5-3	1.4462	SUS329J3L	022Cr23Ni5Mo3N

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 17-4PH stainless steel?

The nearest EN grade is 1.4542, steel name X5CrNiCuNb16-4.

What is the JIS equivalent of 17-4PH stainless steel?

The nearest Japanese grade is SUS630.

What is the Chinese GB equivalent of 17-4PH stainless steel?

The nearest Chinese GB grade is 05Cr17Ni4Cu4Nb.

Is 1.4542 the same as 17-4PH (630)?

1.4542 (X5CrNiCuNb16-4) is the nearest European equivalent of 17-4PH (630), 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 17-4PH (630) used for?

Aerospace fittings, pump and valve shafts, gears, fasteners, and oil and gas components.