It is important to gain knowledge about PH stainless steel. Most especially if you’re about to purchase for your fabrication projects.
Understanding its properties can help you make informed decisions in your own projects.
In this article, we will discuss its several benefits. As well as the manufacturing processes and applications where the material is most often used.
Let’s get through this!
What is PH Stainless Steel?
PH steels are stainless steel alloy that contains high phosphorus levels. It is deeply utilized in many applications where extreme corrosion protections are needed.
It is also called “precipitation hardening” stainless steel. The reason is due to its ability to increase its hardness when exposed to certain temperatures. The phosphorus addition to the alloy increases the resistance on corrosive elements. As a result, it became more resistant to pitting and crevice corrosion.
The Development History
Understanding the history can help you identify potential problems that may arise when using the material.
Let us now learn about the journey of PH steel from the beginning until today.
| Timeframe | The Development of PH Stainless Steel |
| Year 1930s |
|
| 1940-1950 |
|
| 1951-1960 |
|
| 1970s |
|
| 1980-1989 |
|
| 1990-2000 |
|
| 2001-2009 |
|
| 2010s |
|
| 2011-2020 |
|
Precipitation-Hardened (PH) Steel Composition
The composition of PH steel is as follows:
| 16–18% | Chromium |
| 8–10.5% | Nickel |
| 4–7% | Molybdenum |
| 0.45% | Nitrogen |
| 0.2% | Carbon |
| 0.03% | Phosphorus |
| Balance | Iron |
Properties of Precipitation-Hardened SS
By having a better understanding of its properties, you can make wise choices for your manufacturing projects.
Let us now discover both the physical and mechanical properties of PH steels.
Physical Properties
- Density: 7.75 – 8.0 g/cm3
- Tensile Strength: 750 – 1650 MPa
- Yield Strength: 500 – 1250 MPa
- Elongation: 20 – 40%
- Hardness: 28 – 45 HRC
- Thermal Conductivity: 16 – 24 W/(m. K)
- Thermal Expansion: 13 – 15 µm/m.K
Mechanical Properties
- Tensile Strength: Its tensile strength is typically between 1,000 and 1,500 MPa (megapascals).
- Yield Strength: The yield strength is typically between 500 and 1,000 MPa.
- Elongation: The elongation is between 10 to 20%.
- Hardness: Its hardness is typically between 40 to 50 Rockwell C (HRC).
- Ductility: The ductility of precipitation-hardening stainless steel is usually between 15 and 25%.
- Impact Resistance: Its impact resistance is typically between 20 and 40 joules.
APPLICATIONS
PH Stainless Steel has a wide range of applications, including chemical & industrial, medical, and marine environments.
In the chemical and industrial industries, PH steel is often used in tanks, piping, and other equipment. The alloy is also resistant to most acids and bases. Therefore it is an ideal choice for pipe and tube systems in chemical processing plants. In addition, it is also used in chemical storage tanks and reactors.
In the medical field, the said material is used in surgical tools. You can use it manufacturing scalpels, dental tools, and other medical instruments. It is also used for implants and other prosthetics.
However, in marine environments, it is used in boats, ships, and other vessels. It is also used in aquariums and other underwater structures.
Finally, PH steel is also used in the food processing and packaging industry. It is used in kitchen utensils, cookware, and food processing machinery. You can also use the material to make containers and storage tanks for food products.
PH Stainless Steel Advantages
The primary benefit is its outstanding oxidation resistance.
PH steel is highly unaffected by many common forms of corrosive factors. Therefore it is a great choice for applications that are exposed to harsh elements. Additionally, Precipitation hardening steel is extremely durable and can withstand high temperatures.
Another great benefit is its ability to resist stress.
This alloy is exceptionally strong and can withstand high levels of stress. Even without weakening or breaking. Because of this, it became excellent for applications requiring strength and durability. Plus! It is highly formable, allowing for complex shapes and designs.
Finally, the PH stainless steel is highly machinable, allowing for precise machining and fabrication. This makes it a great choice for projects demanding exact tolerances and intricate designs.
SHORTCOMINGS
The primary shortcoming of using PH stainless steel is its susceptibility to corrosion. This type of alloy is less corrosion-resistant than other stainless steel alloys. Also, it is susceptible to pitting and crevice corrosion when exposed to chloride solutions.
Moreover, PH steels also have a lower melting point. Which then makes the material difficult to weld or fabricate.
Another disadvantage, it is not magnetic and has a lower strength than other stainless steel alloys. However, in terms of pricing, this material is more expensive and is not as widely available.
Machining Process
You need to know the machining process for precipitation-hardened steels. Why?
It helps you to ensure that the steel meets quality standards and offers maximum performance for the intended use.
Melting Process: The stainless steel scrap or the raw material is melted down in a furnace to create a molten alloy.
Forging Process: The molten alloy is then forged or shaped into a specific form, either a bar, plate, or sheet.
Hot Rolling Process: The forged stainless steel is subjected to hot rolling in order to reduce its thickness and increase its strength and hardness.
Annealing Process: The hot-rolled stainless steel is heated in order to relieve any stresses, strains, and other imperfections that may be present.
Cold Rolling Process: The annealed stainless steel is then cold rolled to reduce its thickness further and to improve its surface finish.
Pickling: The cold rolled stainless steel is then pickled in a chemical bath to remove impurities and oxides.
Finishing Process: The pickled stainless steel is then polished to the desired finish and then subjected to final quality control.
Tips for Maintenance
PH steel requires proper care to ensure it remains to look its best and preserves its longevity.
Here are some tips for maintenance:
- Clean Regularly: It is important to regularly clean its surfaces to remove any dirt, grime, and fingerprints. Use a mild soap-and-water solution.
- Avoid Abrasive Cleaners: Abrasive cleaners can scratch and damage the surface of stainless steel, so it is important to avoid them.
- Use Protective Coatings: To protect surfaces from corrosion and wear, it is a good idea to apply a protective coating, such as a sealant or wax.
- Polish with a Soft Cloth: To maintain its shine and luster, it’s important to polish the surface regularly. Use a soft cloth to do this.
- Minimize Scratches: To minimize scratching, always use a soft cloth or a microfiber cloth when cleaning. Avoid using steel wool or abrasive pads.
Duplex VS PH Stainless Steel
The major difference between them is in their chemical composition.
Duplex stainless steels have a higher chromium, molybdenum, and nitrogen content than PH steels. Duplex also has higher fatigue strength, perfect for applications that need a high level of mechanical stress.
Compared to PH stainless steel, it has higher sulfur content so, therefore, more resistant to localized corrosion. It also has a lower cost than duplex metal, making it suitable for use in less demanding applications.
CONCLUSION
You have learned now how incredibly valuable and versatile PH stainless steel is. From the kitchen or medical instruments to large-scale engineering projects, this material offers a wide range of utilities. No wonder it is one of the most chosen metals today.
If you still have any concerns, let us know. Please contact our team!