PH grade stainless steel is a type of high-strength stainless steel alloy achieved through a special precipitation hardening heat treatment process. Unlike ordinary stainless steel, which relies on composition optimization to improve performance, the core advantage of PH grade stainless steel stems from heat treatment strengthening. While retaining the excellent corrosion resistance of austenitic stainless steel, its strength can rival or even surpass that of high-strength carbon steel. Essentially, it is an iron-chromium-nickel alloy system. By adding alloying elements such as copper, molybdenum, aluminum, and titanium, combined with a precise heat treatment process, fine precipitates are formed within the alloy, hindering dislocation movement in the crystals. This significantly improves the material's hardness, tensile strength, and wear resistance, with almost no loss of corrosion resistance.
Mainstream Model Comparison
|
Type |
Main Models (with UNS No.) |
Core Characteristics |
Tensile Strength (MPa) |
Applicable Scenarios |
|
Martensitic (Most Commonly Used) |
17-4 PH (S17400), 15-5 PH (S15500) |
High cost-performance, excellent corrosion resistance and machinability; 15-5 PH has strict impurity control and superior transverse toughness |
1170-1376 |
Aerospace components, valves, nuclear reactor parts, thick-section chemical equipment |
|
Semi-Austenitic |
17-7 PH (S17700) |
Excellent formability, easy stamping and bending in annealed state; corrosion resistance slightly lower than 17-4 PH |
≥1400 |
Aerospace bellows, springs, diaphragms and other high-strength components with complex shapes |
|
Austenitic |
A286 (S66286) |
Non-magnetic, excellent high-temperature resistance, maintains austenitic structure after heat treatment |
850-1000 |
High-temperature working conditions such as jet engine blades and turbine components |
Hardening Principle of PH Grade Stainless Steel
1. Solution Treatment: Heating the alloy to a high temperature of 1000-1065℃ allows alloying elements such as copper and molybdenum to fully dissolve into the iron-based solid solution, breaking the original compositional inhomogeneity.
2. Quenching Treatment: Rapid cooling (such as water cooling or air cooling) "locks" the alloying elements in the solid solution, inhibiting the precipitation of harmful phases and forming an unstable supersaturated solid solution. 3. Aging treatment: Holding at a low temperature of 450-760℃ causes alloying elements in the supersaturated solid solution to precipitate and form fine precipitates. These precipitates act as microscopic obstacles, hindering dislocation movement and ultimately achieving a leap in strength and hardness.
