Grade 309 / 309S are austenitic chromium-nickel stainless steels, which are often used for high temperature applications. Due to their high chromium and nickel content, Grade 309 / 309S pipes are highly corrosion resistant, and have outstanding resistance to oxidation. Also, they exhibit excellent heat resistance while providing good strength at ambient or elevated temperatures. However, the only significant difference between 309 and 309S is the carbon content. Grade 309S stainless steel pipes have a much less carbon composition, which minimizes carbide precipitation, and improves weldability.
The following properties of 309 / 309S stainless steel pipes make them suitable for specific applications:
Superior heat resisting austenitic stainless steel Good for continuous exposure to 2000 degree F Intermittent service to 1800 degree F.
The grade does not perform as well as grade 600 or 800 steel in reducing, nitriding or carburizing atmospheres. However, it does outperform most heat resistant stainless steels in these conditions.
309 / 309S stainless steel pipes and tubes are used exclusively for their excellent oxidation resistance, and strength at high temperatures. Additionally, they offer good resistance to creep deformation and extreme environment. Some examples include, but are not limited to:
|Typical Chemical Composition % (max values, unless noted)|
|309||max: 0.4 min: 0.8||2.0 max||0.75 max||0.045 max||0.03 max||min: 22.0 max: 24.0||min: 12.0max: 15.0||Balance|
|309H||min: 0.04 max: 0.08||2.0 max||0.75 max||0.045 max||0.03 max||min: 22.0 max: 24.0||min: 12.0max: 15.0||Balance|
|Typical Room Temperature Mechanical Properties|
|Grade||Tensile StrengthKSI (MPA)||Yield Strength 0.2% KSI offset KSI (MPA)||Elongation (% in 2ʺ(50.8 mm)||Hardness (Brinell) MAX|
Which is better ss304 or ss316?
Since Type 316 stainless steel alloy contains molybdenum bearing it has a greater resistance to chemical attack than 304. Type 316 is durable, easy-to-fabricate, clean, weld and finish. It is considerably more resistant to solutions of sulfuric acid, chlorides, bromides, iodides and fatty acids at high temperature.
What is good quality stainless steel?
304 stainless steel is the most common form of stainless steel used around the world due to excellent corrosion resistance and value. 304 can withstand corrosion from most oxidizing acids. That durability makes 304 easy to sanitize, and therefore ideal for kitchen and food applications.
What is the difference between 304, 304H and 304L?
In fact, the content of chromium and nickel is 304 stainless steel, and the composition contains 18% chromium (Cr) and 8% nickel (Ni), but the main difference lies in the carbon content.
304L is an ultra-low carbon stainless steel. The carbon content is reduced to less than 0.03%, which can avoid intergranular corrosion. In theory, the effect of stress corrosion resistance is stronger than that of 304, but the effect is not obvious in practical applications. The purpose of reducing carbon and adding titanium is the same, but the smelting cost of titanium-added 321 is higher, the molten steel is thick, and the price is more expensive.
The H in 304H refers to high temperature. High carbon content is the guarantee of high temperature strength. GB150 requires that when austenitic steel is used above 525 degrees, the carbon content should not be less than 0.04%. Carbide is the strengthening phase, especially the high temperature strength. Better than pure austenite.
Among the three, the highest carbon content is 304H, the lowest carbon content is 304L, and the carbon content of 304 stainless steel is between the two. The higher the carbon content, the worse the corrosion resistance of stainless steel and the easier it is to rust. The difference in carbon content also causes the price to be different, or the requirements for different uses are also different.
Why is stainless steel so expensive?
Stainless steel is more expensive to produce because of the addition of the variety of alloying elements, such as iron, chromium, nickel, manganese and copper. … The chromium attaches itself to oxygen more readily than iron and thus creates a chromium oxide layer which protects the metal from degradation.
What is the safest stainless steel?
Stainless steel cookware is generally recognized as a safe material for cookware. Any good quality stainless steel, be it 304 or 316 stainless steel, is a better choice than most of the other available materials. For example, coated aluminum pans lose their non-stick over time.
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