17-4PH

17-4PH alloy is a precipitation, hardening, martensitic stainless steel composed of copper, niobium/columb. Features: After heat treatment, the mechanical properties of the product are more perfect, and can reach a compressive strength of up to 1100-1300 Mpa (160-190 ksi). This grade cannot be used at temperatures higher than 300o C (572o 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 and 430.

Application field/17-4PH Edit

· Offshore platforms, helicopter decks, other platforms

· food industry

· Pulp and Paper Industry

· Aerospace (turbine blades)

· machinery parts

·Nuclear Waste Barrel

17-4PH17-4PH alloy is precipitation, hardening, martensitic stainless steel.

17-4PH alloy is a precipitation, hardening, martensitic stainless steel composed of copper, niobium/columb.

This grade has high strength, hardness (up to 300o C/572o F) and corrosion resistance.

After heat treatment, the mechanical properties of the product are more perfect, and can reach a compressive strength of up to 1100-1300 mpa (160-190 ksi).

This grade cannot be used at temperatures higher than 300o C (572o 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 and 430.

Chemical composition/17-4PH Edit

"Chinese brand 0Cr17Ni4Cu4Nb 05Cr17Ni4Cu4Nb

C: ≤0.07 Si: ≤1.00 Mn: ≤1.00 P: ≤0.035 S: ≤0.030 Ni: 3.00-5.00 Cr: 15.0-17.5

Mo:- Cu: 3.00-5.00 Nb: 0.15-0.45 Other:-

American ASTM A564 630, ASTM A564 630, UNS630

chemical composition

C: ≤0.07 Si: ≤1.00 Mn: ≤1.00 P: ≤0.040 S: ≤0.030 Ni: 3.00-5.00 Cr: 15.0-17.5

Mo:- Cu: 3.00-5.00 Nb: 0.15-0.45 Other:-

Japan SUS630

Chemical composition C: ≤0.07 Si: ≤1.00 Mn: ≤1.00 P: ≤0.040

S: ≤0.030 Ni: 3.00-5.00 Cr: 15.0-17.5 Mo:-Cu: 3.00-5.00 Nb+Tao: 0.15-0.45 Other:-

Mechanical properties/17-4PH Edit

1. Density of 17-4PH precipitation hardening steel: 7.78kg/m3

2. Melting point of 17-4PH precipitation hardening steel: 1400～1440℃

3. The specific heat capacity of 17-4PH precipitation hardening steel: 502J/(kg·℃).

The room temperature mechanical properties of the steel are shown in the table below

Mechanical properties of 17-4PH precipitation hardening stainless steel:

1. Tensile strength σb (MPa): aging at 480℃≥1310, ageing at 550℃≥1060, ageing at 580℃≥1000, ageing at 620℃≥930.

2. Conditional yield strength σ0.2 (MPa): aging at 480℃≥1180, aging at 550℃≥1000, ageing at 580≥865, ageing at 620℃≥725.

3. Elongation δ5 (%): Ageing at 480℃≥10, ageing at 550℃≥12, ageing at 580℃≥13, ageing at 620℃≥16.

4. Reduction of area ψ (%): aging at 480℃≥40, aging at 550℃≥45, aging at 580℃≥45, aging at 620℃≥50.

5. Hardness: solid solution ≤363HB and ≤38HRC, 480℃ aging ≥375HB and ≥40HRC, 550℃ aging ≥331HB and ≥35HRC, 580℃ aging ≥302HB and ≥31HRC, 620 aging ≥277HB and ≥28HRC.

17-4PH precipitation hardening stainless steel heat treatment specification:

1. Solid solution and rapid cooling at 1020～1060℃.

2. Aging at 480℃, after solution treatment, air cooling at 470～490℃.

3. Aging at 550℃, after solution treatment, air cooling at 540～560℃.

4. Aging at 580℃, after solution treatment, air cooling at 570～590℃.

5. Aging at 620℃, after solution treatment, air cooling at 610～630℃.

6. Metallographic structure: The structure is characterized by precipitation hardening.

Corrosion resistance of 17-4PH precipitation hardening stainless steel:

The corrosion resistance of 17-4PH precipitation hardening steel is better than any other standard hardenable stainless steel. In most cases, its corrosion resistance is no less than 304. If there is a risk of stress corrosion cracking, the higher curing temperature must be higher than 550oC (1022oF), preferably 590oC (1094oF), and the best tempering temperature in the chloride medium is 550oC-1022oF. This alloy is susceptible to corrosion or crack corrosion in static sea water. Its corrosion resistance in petrochemical, food processing and paper industry is the same as 304L grade.

Corrosion resistance/17-4PH 編輯

See the table below. Corrosion resistance of 17-4PH steel [corrosion rate g/(m2h)]

Process performance/17-4PH 編輯

This steel is generally not cold worked. The thermal processing temperature is 1000~1170°C. For parts larger than 76mm or complicated in shape, they should be returned to the furnace and heated to the original thermal processing temperature in time after thermal processing, and then slowly cooled.
The heat treatment system of the steel is as follows:

Precipitation hardening:

480~630°C 1h air cooling to obtain H900, H925, H1025,

H1150 status. (Both precipitation hardened martensite) ----------------------------------------- -------------------〉

The steel can be welded by any method of welding stainless steel. It can be welded in solid solution, aging or over-aging state. There is no need to preheat before welding. When the weld strength is required to be 90% of the strength after aging, then re-solution and aging treatment are required after welding. This steel can also be brazed, and the appropriate brazing temperature is the solution treatment temperature of this steel.

Physical properties/17-4PH 編輯

Density: 7780 kg/m2

Coefficient of linear expansion: (H900 heat treatment state)

At 20~100°C, 0.0000108 /K; At 20~200°C, 0.0001016 /K; At 20~300°C, 0.00001136 /K

Thermal conductivity:

At 100°C, 17W/(m*K); At 300°C, 20W/(m*K); At 500°C, 23W/(m*K)

Elastic Modulus:

At 20°C, 191000 MPa; At 100°C, 191000 MPa; At 320°C, 181000 MPa