15-5PH / X5CrNiCuNb15-5 vs 630 / 17-4PH: Both PH stainless — 15-5PH has better transverse toughness
15-5PH / X5CrNiCuNb15-5 vs 630 / 17-4PH
Side-by-side chemical composition and mechanical property comparison.
Overview
15-5PH / X5CrNiCuNb15-5
1.4545
Martensitic precipitation-hardening stainless steel. Similar to 17-4PH but with better transverse ductility and toughness due to lower delta ferrite. Used for aerospace structural components, nuclear reactor parts, food processing equipment, and high-performance fasteners.
630 / 17-4PH
1.4542
Precipitation-hardening martensitic stainless steel — the highest-strength stainless in common use. Solution anneal at 1040°C then age at 480-620°C for UTS >1300 MPa. Corrosion resistance similar to 304. Cu+Nb precipitation hardening. Trade names include 17-4PH, SUS630. Used for aerospace structural parts, turbine blades, valve components, nuclear waste casks, medical instruments, and oil/gas equipment.
| 15-5PH / X5CrNiCuNb15-5 | 630 / 17-4PH | |
|---|---|---|
| Material Number | 1.4545 | 1.4542 |
| Category | Stainless Steel | Stainless Steel |
| Standard | AMS 5659 | EN 10088-3 |
Chemical composition (wt%)
| Element | 15-5PH / X5CrNiCuNb15-5 | 630 / 17-4PH | Overlap |
|---|---|---|---|
| C | 0–0.07% | 0–0.07% | OK |
| Si | 0–1% | 0–0.7% | OK |
| Mn | 0–1% | 0–1.5% | OK |
| P | 0–0.03% | 0–0.04% | OK |
Mechanical properties
| Property | 15-5PH / X5CrNiCuNb15-5 | 630 / 17-4PH | Unit |
|---|---|---|---|
| tensile_strength | ≥ 1310 | ≥ 1310 | MPa |
| yield_strength | ≥ 1170 | ≥ 1170 | MPa |
| elongation | ≥ 10 | ≥ 10 | % |
Compatibility Assessment
630 (17-4PH) and 15-5PH have nearly identical strength levels. 15-5PH has higher Ni (5 vs 4%) giving better transverse toughness and more uniform properties. 17-4PH is cheaper and more widely available. Choose 15-5PH for critical aerospace; 17-4PH for general high-strength applications.
Frequently Asked Questions
Is 15-5PH / X5CrNiCuNb15-5 the same as 630 / 17-4PH?
15-5PH / X5CrNiCuNb15-5 and 630 / 17-4PH have a 80% composition overlap. Both PH stainless — 15-5PH has better transverse toughness
Can I replace 15-5PH / X5CrNiCuNb15-5 with 630 / 17-4PH?
In many cases, yes. The compositions overlap significantly (80%). However, always verify mechanical property requirements and heat treatment compatibility for your specific application.
What is the difference between 15-5PH / X5CrNiCuNb15-5 and 630 / 17-4PH?
The main differences are in the following elements: Cr, Ni, Cu. 15-5PH / X5CrNiCuNb15-5 is a Stainless Steel grade, while 630 / 17-4PH is a Stainless Steel grade.
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Data provided for reference only. Always verify against the applicable specification for critical applications.
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