15-7PH Application field:
Used for high-strength containers, parts and structural parts with certain corrosion resistance requirements.
Category:
Semi-austenitic precipitation hardening stainless steel
Standard:
GB/T 1220- 1992
Scope of application:
It is developed by replacing 2% chromium in 0Cr 17Ni7Al steel with 2% molybdenum. Its basic properties are similar to those of 0Cr 17Ni7Al steel, but its comprehensive properties are better. It can withstand all kinds of cold forming and welding processes in austenitic state, and the highest strength can be obtained after heat treatment; It has excellent high temperature strength below 550℃.
15-7PH stainless steel is widely used in chemical industry to manufacture thin-walled structural parts and other structural parts of aviation and various chemical equipment. It is mainly used to manufacture various containers, pipes, springs, diaphragms, valve membranes, ship shafts, compressor discs, reactor parts, etc., with good corrosion resistance and high strength.
Heat treatment conditions
There are three heat treatment systems in one state: TH 1050 state, RH950 state and CH900 state.
condition
1050℃ solution treatment, water cooling or air cooling. The metallographic structure is characterized by austenite.
TH 1050
After solid solution treatment at 1050℃, keep the temperature at 760℃ 15℃ for 90min, cool to 15℃ or room temperature within 1h, keep the temperature for 30min, and then heat to 565℃ 10℃ for 90min. Metallographic structure is characterized by precipitation hardening martensite.
RH950
After solution treatment at 1050℃, keep the temperature at 955℃ 15℃ 10min, cool to room temperature with air, cool to-73℃ 6℃ within 24 hours, keep the temperature for 8 hours, and then heat to 510℃ 6℃. Metallographic structure is characterized by precipitation hardening martensite.
CH900
1050℃ solution treatment, cold rolling with 60% deformation, heating to 490℃ for 60 minutes, and air cooling to room temperature. Metallographic structure is characterized by precipitation hardening martensite.
Mechanical properties:
Mechanical properties of 15-7PH at room temperature.
Tensile strength σb (MPa):565℃ aging: ≥1210; 5 10℃ aging: ≥1323;
Conditional yield strength σ0.2 (MPa):565℃ aging: ≥1097.6; 5 10℃ aging: ≥1210;
Elongation δ5 (%):565℃ aging: ≥17; 5 10℃ aging: ≥ 6;
Area shrinkage ψ (%):565℃ aging: ≥ 25; 5 10℃ aging: ≥ 20;
Hardness HB:A Status: ≤ 269; Aging at 565℃: ≥ 375; 5 10℃ aging: ≥ 388;
Physical properties:
Density ρ (kg m-3): A Status: 7804, TH 1050:7685, RH950:7680, ch 900:7670；;
Resistivity (n ω m): state A: 0.800, TH 1050:0.820, RH950:0.830, ch 900:0.840；;
Thermal conductivity λ:17w/(m k) at 50℃,18w/(m k) at 260℃ and 21w/(m k) at 480℃;
Elastic modulus e (room temperature):199 GPA;
Linear expansion coefficient α(TH 1050 state): 10.08K- 1 at 20 ~ 16℃, and11at 20 ~ 3℃.
Melting point:1415 ~1450℃;
Process performance:
Technological properties include cold working and hot working properties, heat treatment properties and welding properties.
Cold and hot workability
15-7PH stainless steel has austenite structure in solid solution state, which can withstand cold working, but it has a high tendency of cold working hardening. Therefore, cold rolling, cold stamping, etc. Most of them adopt the processes of less passes, large reduction and multiple intermediate solid solution treatment. Its hot working is not difficult, and the suitable hot working temperature is 950- 1 150℃.
Heat treatment performance
The heat treatment of 15-7PH stainless steel is complicated and very strict. Only by controlling the specified temperature, time and cooling rate can ideal performance be obtained.
welding performance
The welding of 15-7PH stainless steel is the same as that of ordinary stainless steel. Arc welding, resistance welding and gas shielded welding are all acceptable, among which gas shielded welding is the best. Welding is generally carried out in the state of material solution treatment, and preheating is not needed before welding, but it is best to carry out full heat treatment after welding. When the weld requires high strength, 0Cr 17Ni7A 1 steel welding wire with less δ-ferrite content is often selected. When the weld strength is not high and the corrosion resistance is high, austenitic stainless steel welding wire can be used.
Main specifications:
15-7PH seamless pipe, 15-7PH steel plate, 15-7PH round steel, 15-7PH forging, 15-7PH flange, 15-7PH ring. 15-7PH welding wire and welding material, 15-7PH round cake, 15-7PH flat steel, 15-7PH hexagonal bar, 15-7PH head,15-.
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