Precipitation hardening stainless steel, also known as PH Steel, is a type of stainless steel in which different types and amounts of strengthening elements, as well as different types and amounts of carbides, nitrides, carbonitrides, and intermetallic compounds, are precipitated during the precipitation hardening process. Precipitation hardened stainless steel grade is not only strong but also tough and corrosion resistant. Our investment casting foundry can cast precipitation hardened stainless steel based on your drawings, specifications, and usage situation.
Austenitic and ferritic alloys account for 95% of commercial stainless steel applications on the market today, so it’s easy to see why they’re the most well-known alloys. Why is precipitation hardening so frequently ignored? In today’s post, we’ll look at the material’s advantageous properties as well as the precipitation hardening process. Simultaneously, we’ll highlight some of the most popular applications and the industries where you’re most likely to find them.
What is precipitation hardening?
The chemistry of a material determines the categories of stainless steel; however, with precipitation hardening, it’s more about the process than the alloying agents, which is why other metals can also undergo a similar process. The precipitation hardening process applies to aluminum, nickel, and titanium.
Precipitation hardening is a type of heat treatment that can strengthen malleable materials like steel. The technical process entails heating the metal in such a way that fine particles or impurities are produced that obstruct the movement of defects in the metal’s crystal lattice structure. The material is strengthened as its plasticity decreases.
Depending on the techniques used, the metal can react in a variety of ways when heated. Consider how water vapor freezes in the air. Depending on the atmospheric conditions, the new particles may take the form of clouds, hail, or snow. Similarly, precipitation in solids can have vastly different properties.
Precipitation hardening differs from ordinary tempering in that the alloys must be kept at a constant elevated temperature for a specified time to allow precipitation to occur. This is referred to as “aging the metal.”
What is a typical precipitation hardening?
The hardening process generally consists of three major steps: First, the metal must be treated with a solution. The metal will be heated to a high temperature during this stage to dissolve any precipitates and alloying agents into a supersaturated solution. Temperatures in the 1800° to 1950°F range are typical and can occur in conjunction with the hot-rolling process.
The metal will then be quenched to bring it down to room temperature.
This can happen quickly enough in air, oil, or water to produce a supersaturated solid solution. A slower cool down will produce a coarser grain size than a faster cool down. In general, the finer the grain size, the better the finished alloy.
What are some of the common applications of precipitation hardening of stainless steel?
Precipitation hardened stainless steel is most commonly found in high-tech industries such as aerospace and energy due to its superior strength. 17-4, for example, is widely used in the aerospace industry, as well as in petroleum and chemical applications. Gears, valves, and other engine parts, turbine blades, high-strength shafts, molding dies, and nuclear waste casks are some of the other applications for precipitation hardening alloys.
What are the most popular hardening alloys for precipitation?
Martensitic precipitation hardening stainless steels are the most widely used PH grades. These alloys typically have an austenitic structure during the heat treatment process, but when cooled to room temperature, they undergo a transformation that more closely resembles martensitic alloys. 17-4 (17 percent chromium, 4 percent nickel), 13-8 (13 percent Cr 8 percent Ni), and 15-5 are some of the more common grades (15 percent Cr 5 percent Ni). These grades can be heat treated to achieve high strength while also providing excellent corrosion resistance and machinability. They’re all attracted to each other.
Specific conditions, such as conditions H900, H1025, H1100, and H1150, are achieved by age hardening martensitic PH grades. The temperature of the age hardening process is indicated by these conditions. Each condition will produce different mechanical properties in the metal, but they will also differ in machinability and corrosion resistance. After age hardening, the martensitic PH grades have very good dimensional stability.
On the other hand, austenitic precipitation hardening alloys retain their basic austenitic structure even after heat treatment. These alloys are typically less strong than the other two categories, but they have the advantage of being completely austenitic. A286. For example, it is suitable for applications requiring high strength and corrosion resistance up to 1300°F
