Stainless steel strips 17-4 PH and 17-7 PH are two types of precipitation hardening stainless steel that belong to the Martensitic grades steel.
Both 17-4 PH and 17-7 PH have the basic elements carbon, chromium, and nickel. The main difference between the two types of precipitation hardening stainless steel is that the nickel is replaced by molybdenum in 17-7 PH. This leads to a better resistance against creep, corrosion, stress relief at elevated temperatures and also makes it softer than 17-4 PH.
Although there are too many factors to consider when choosing the best out of the two, the product data from both the manufacturers are in a close range and these two are considered to be within a dimension of error for this reason.
Let’s keep reading.
What is 17-4PH Stainless Steel Strip?
17-4 PH stainless steel strip, also called 630 precipitation hardening stainless steel strip.
17-4PH alloy is a precipitation, hardening, martensitic stainless steel composed of copper, niobium/columb.
After heat treatment, the mechanical properties of the strip product are more perfect, and can reach a compressive strength of up to 1100-1300 Mpa (160-190 ksi).
Grade 17-4 PH stainless steel strip cannot be used at temperatures higher than 300°C (572°F) or very low temperatures.
It has good corrosion resistance to the atmosphere and diluted acids or salts.
Its corrosion resistance is the same as 304 stainless steel strip and 430 stainless steel strip.
What is 17-7PH Stainless Steel Strip?
17-7 PH stainless steel strip, also called 631 precipitation hardening stainless steel strip.
It is a precipitation hardening stainless steel strip that provides high strength and hardness, excellent fatigue properties, good corrosion resistance, good formability, and minimum distortion upon heat treatment.
The alloy strip provides valuable property combinations particularly well suited for aerospace applications.
This special alloy strip also provides benefits for other applications requiring high strength and good corrosion resistance, as well as excellent properties for flat springs at temperatures up to 600°F (316°C).
According to the processing method, the edge of 17-7 PH stainless steel strip can be produced as slit and round types.
The conventional thickness is between 0.1mm and 3.0mm, and the width is less than 600mm.
Different length can be produced according to your detailed request.
Differences Between 17-4PH Stainless Steel Strips and 17-7PH Stainless Steel Strips
Chemical Composition
The chemical components of grade 17-4PH stainless steel strip is summarized in the following table:
| C | Si | Mn | P | S | Cr | Ni | Cu | Nb |
| 0.07 max | 1.00 max | 1.00 max | 0.040 max | 0.030 max | 15.00~17.50 | 3.0~5.0 | 3.0~5.0 | 0.15~0.45 |
17-7PH Chemical Components ( % )
- Carbon 0.09 max.
- Manganese 1.00 max.
- Phosphorus 0.040 max.
- Sulfur 0.030 max.
- Silicon 1.00 max.
- Chromium 16.00 – 18.00
- Nickel 6.50 – 7.75
- Aluminum 0.75 – 1.50
Mechanical Properties
17-4PH Stainless Steel Strip Mechanical Properties
The mechanical properties of grade 17-4PH stainless steel strip is summarized in the following table:
| Property | A | H 900 | H 925 | H 1025 | H 1075 | H 1150 | H 1150-M |
| UTS | 1103 | 1448 | 1379 | 1276 | 1207 | 1103 | 1034 |
| 0.2% YS | 1000 | 1379 | 1345 | 1172 | 1148 | 1034 | 896 |
| Elongation % in 50mm | 5 | 7 | 8 | 8 | 8 | 11 | 12 |
| Hardness (rockwell) | C35 | C45 | C43 | C38 | C37 | C35 | C33 |
17-7PH Stainless Steel Strip Mechanical Properties
Property | A | T | TH 1050 | A1750 | R100 | RH950 | C | CH900 |
UTS | 896 | 1000 | 1379 | 917 | 1207 | 1620 | 1517 | 1827 |
YS | 276 | 690 | 1276 | 290 | 793 | 1517 | 1310 | 1793 |
Elongation | 35 | 9 | 9 | 19 | 9 | 6 | 5 | 2 |
Hardness, Rockwell | B85 | C31 | C43 | B85 | C36.5 | C48 | C43 | C49 |
Applications
What Is 17-4PH Stainless Steel Strip Used For?
17-4PH is a martensitic precipitation hardening stainless steel.
It has high strength, high hardness, good welding performance and corrosion resistance.
It has been widely used in following industries:
- Oil field equipment
- Chemical process equipment
- Fittings and pump shafts
- Gears
- Paper mill equipment
- Aircraft parts
- Flanges and valves
- Other Precision Parts
What Is 17-7PH Stainless Steel Strip Used For?
Due to the high strength and good corrosion resistance, quality grade 17-7PH stainless steel strip is widely used for following applications.
- Retaining rings
- Springs
- Valves and flanges
- Gears
- Aircraft parts
