Description
17 – 4 PH Stainless Steel , UNS S17400, 1.4548, SUS630
17-4PH is a precipitation hardening martensitic stainless steel, which combines high strength and hardness (after heat treatment) with excellent corrosion resistance, and is suitable for easy fabrication.
Solution Treatments.
As supplied 17-4 PH is usually in the solution treated condition (Condition A). It can be heat treated at different temperatures to offer a wide range of properties.
| Condition | Hardening | Hardening | Type of Cooling | Hardness | |
| Temperature | Time | Brinell | Rockwell C | ||
| A | 1038°C | 1/2 | Oil/Air (to below 32°C) | 363 max. | 39 max. |
| H900 | 480°C | 1 | Air | 420 | 44 |
| H925 | 594°C | 4 | Air | 409 | 42 |
| H1025 | 55°C | 4 | Air | 352 | 38 |
| H1075 | 85°C | 4 | Air | 341 | 36 |
| H1100 | 595°C | 4 | Air | 332 | 35 |
| H1150 | 621°C | 4 | Air | 311 | 33 |
| H1150+H1150 |
760°C
760°C |
4 followed by 4 |
Air
Air |
302 |
33 |
| H1150-M |
760°C
620°C |
2 followed by 4 |
Air
Air |
277 |
27 |
Mechanical Properties of 17.4PH / SUS 630 (longitudinal)
| Condition: | |||||||||
| A | H900 | H925 | H1025 | H1075 | H1100 | H1150 | H1150+ H1150 |
H1150M |
|
| Tensile Strength N/mm2 |
1034 | 1380 | 1310 | 1170 | 1140 | 1035 | 1000 | 965 | 860 |
| 0.2% YS N/mm2 |
760 | 1275 | 1200 | 1140 | 1035 | 930 | 860 | 760 | 585 |
| Reduction of Area % |
30-60 | 50 | 54 | 56 | 58 | 58 | 60 | 60 | 68 |
| Elongation % |
6-15 | 14 | 14 | 15 | 16 | 17 | 19 | 20 | 22 |
| Charpy Impact J |
– | 20 | 34 | 47 | 54 | 61 | 68 | 108 | 135 |
Corrosion Resistance
17.4PH stainless steel has excellent corrosion resistance. Corrosion tests and service experience have shown that in all aged conditions it is superior to standard hardenable stainless grades such as SUS 420, SUS 431 and SUS 410. Its corrosion resistance is comparable to grade SUS 304 Stainless.
Welding
Arc and resistance welding processes used on standard grades of stainless steel are applicable to 17.4 PH stainless steel. The low hardness enables sections, up to 100mm, to be welded without requiring pre heating.
Fabrication
17/4PH Condition is suitable for limited cold forming, H1100, H1150 and overaged conditions are more suitable when severe cold forming is required.
Machining
17/4 PH Condition has machining characteristics similar to stainless steel grade SS302, SS304 and SS410. The high hardness and strength in Condition H900 is the most difficult to machine and the material should be machined at 60% of the rate which is used for Condition A.
Nitriding
To increase the resistance to surface wear, with a slight decrease in corrosion resistance, 17-4PH / SUS630 stainless steel can be nitrided. An approximate hardness of 64/67HRc can be achieved, with a surface hardness depth of up to 0.15mm when nitrided at 45°C, while still maintaining a high core strength.
