# 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.

| System | Designation |
|---|---|
| AISI / ASTM / SAE | 17-4PH (630) |
| EN steel name | X5CrNiCuNb16-4 |
| EN steel number | 1.4542 |
| JIS | SUS630 |
| China GB | 05Cr17Ni4Cu4Nb |

Family: Precipitation-hardening stainless

## 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

- 410 stainless steel (1.4006): Conventional hardenable martensitic grade
- 420 stainless steel (1.4021): Higher-hardness martensitic grade

Equivalents are nearest matches, not identical grades. The governing standard or mill certificate decides.

## FAQ

**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.

Source page: https://machinistcharts.com/material/17-4ph-stainless/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)