If you thought that stainless steel never stains judging by the name, you’d be totally wrong.

They do have excellent resistance to a wide range of atmospheric environments and many corrosive media. They might be subject to pitting and crevice corrosion in warm chloride environments and to stress corrosion cracking above about 60 °C.

To make full use of different SS grades we have to know what the obvious differences are between 17-4PH stainless steel vs. 304 stainless steel vs. 316-grade stainless steel. Here, We’re going to help simplify it, to show you every detail of them.

Conclusion of Difference Between 17-4PH vs. 304 vs. 316 Stainless Steel

304ss-vs-316ss material

Here we list out a brief comparison. Hope it is useful for you.

Grade Different Applications
17-4 PH stainless steel It has higher hardening content and/or good corrosion resistance at temperatures of up to 600 °F (316 °C). Its valuable combination of properties gives designers opportunities to add reliability to their products while simplifying fabrication and often reducing costs. Ideal for applications in highly corrosive environments, like the petroleum and chemical industries.
304 stainless steel It cannot be heat-hardened and is also non-magnetic. While this grade of stainless steel won’t rust in normal environments, it will tarnish and has a strong resistance to the effect of various chemicals and acids. 304 stainless steel is very often used in the food, brewing, and dairy industries.
316 stainless steel This product offers high tensile strength. It is non-magnetic and must be hardened through cold working. The difference between type 304 and 316 stainless steel is the incorporation of molybdenum of up to 3%. It has better corrosion resistance than 304. This grade of stainless steel is commonly used in the surgical industry, paper pulp industry, and in the production of dyes and chemicals.

Comparison Table of Chemical Composition

CHEMICAL COMPOSITION
GRADES >> 17-4PH SS304 SS316
Carbon 0.06 0.07 0.06
Manganese 0.9 2 2
Phosphorous 0.03 0.05 0.045
Sulfur 0.02 0.03 0.02
Silicon 0.9 0.5 0.6
Copper, Columbium and Tantalum 4 N/A N/A
Molybdenum N/A N/A 2.1
Nickel 4 8.5 8
Chromium 17.5 18.5 18

Comparison Table of Mechanical Properties

MECHANICAL PROPERTIES & STRENGTH
GRADES >> 17-4PH SS304 SS316
Tensile Strength Mpa 1276 515 545
Yield Strength Mpa 1170 205 275
Hardness (HB) 350 215 220
Elongation % 8%Min 40%Min 45%Min

 

17-4 PH Stainless Steel

Advantages and Disadvantages of 17-4 PH Stainless Steel

Type 17-4 PH stainless steel is the most widely used of all the precipitation-hardening stainless steel. Its valuable combination of properties gives designers opportunities to add reliability to their products while simplifying fabrication and often reducing costs. Type 17-4 PH is a martensitic precipitation-hardening stainless steel that provides an outstanding combination of high strength, good corrosion resistance, and good mechanical properties at temperatures up to 600°F (316°C). Its unique combination of properties makes this alloy an effective solution to many design and production problems.

But when the alloy is exposed to seacoast atmosphere, it will gradually develop overall light rusting and pitting in all heat-treated conditions. In common with other stainless steels, 17-4 material is subject to crevice attack if exposed to stagnant seawater for any length of time.

17-4 PH Stainless Steel Applications

stainless steel casting parts

Due to its excellent resistance to corrosion, it is well suited to applications that require ease of fabrication and then the addition of strength/hardness for improved reliability. Such as:

  • Aerospace applications
  • Chemical processing equipment
  • Oil and petroleum refining equipment
  • Food processing equipment

304 Stainless Steel

304 stainless steel is the most common form of stainless steel used around the world, due to its excellent corrosion resistance and value. It contains between 16 and 24 percent chromium and up to 35 percent nickel, as well as small amounts of carbon and manganese. The most common form of 304 stainless steel is 18-8 (18/8) stainless steel, which contains 18 percent chromium and 8 percent nickel.

Advantages and Disadvantages of 304 Stainless Steel

The main benefit of 304 stainless steel is usually considered to be one of the strongest of the mild carbon steel available on the market. It has a high level of resistance to corrosion. 304 can withstand corrosion from most oxidizing acids. That durability makes 304 easy to sanitize, and therefore ideal for kitchen and food applications. It is much easier to mold than 316 stainless steel.

However, like 18-8 grade stainless steel, it does have one weakness: it is susceptible to corrosion from chloride solutions, or from saline environments like the coast. Chloride ions can create localized areas of corrosion, called “pitting,” which can spread beneath protective chromium barriers to compromise internal structures. Solutions with as little as 25 ppm of sodium chloride can begin to have a corrosive effect.

304 Stainless Steel Applications

  • Storage tanks
  • Fasteners and finishing hardware (screws, nuts, bolts, plates, handles)
  • Residential sinks and sink parts
  • Indoor architectural/decorative hardware (panels, sculptures, sconces)
  • Equipment tubing
  • Residential appliances

316 Stainless Steel

316 grade is the second-most common form of stainless steel. It has almost the same physical and mechanical properties as 304 stainless steel. The key difference is that 316 stainless steel contains an addition of molybdenum (up to 3%), which gives it improved corrosion resistance. This is particularly apparent for pitting and crevice corrosion in chloride environments.

Advantages and Disadvantages of 316 Stainless Steel

Stainless steel 316 has excellent corrosion resistance when exposed to a range of corrosive environments and media. It is usually regarded as “marine grade” stainless steel but is not resistant to warm seawater. Warm chloride environments can cause pitting and crevice corrosion. Grade 316 is also subject to stress corrosion cracking above around 60°C. Besides, 316 price is more expensive than 304 costs.

316 Stainless Steel Application

316 stainless steel is commonly used in many industrial applications involving processing chemicals, as well as high-saline environments such as coastal regions and outdoor areas where de-icing salts are common. Due to its non-reactive qualities, 316 stainless steel is also used in the manufacture of medical surgical instruments.

aerospace stainless steel casting parts

  • Industrial equipment is used in Pharmaceutical manufacturing, Chemical manufacturing
  • Industrial and chemical transportation
  • Pressure vessels
  • Cisterns and pipes for chemical applications
  • Medical equipment where non-surgical steel
  • Marine equipment
  • Outdoor site furnishings
  • Commercial kitchens
  • Food production and processing in saline environments
  • Commercial appliances

Stainless Steel Casting Foundry

SIPX casting is a stainless steel casting Foundry and Supplier in China. We can manufacture different grades of stainless steel casting products. Choosing the correct grade of stainless steel is essential to ensure your product quality. Now we know the difference between 17-4PH stainless steel, 304, and 316-grade stainless steel. You can make a better choice for your application in terms of casting.

Kindly contact us for more information and advice on our stainless steel foundry castings. You will get a professional answer.