how to check stainless steel 304 and 316

Introduction to Stainless Steel 304 and 316

Stainless steel 304 and 316 are two of the most widely used austenitic alloys, valued for their corrosion resistance and versatility in industries like chemical processing, food production, and marine applications. Both are non-magnetic and comply with standards like ASME SA240 and ASTM A240, but they differ in composition and performance. 304 is cost-effective for general use, while 316, with added molybdenum, excels in chloride-rich environments.

Knowing how to identify these grades is crucial for ensuring the right material is used. Gangsteel, a leading manufacturer and exporter in China, supplies both sa 240 304 material and sa 240 316 material with certifications. As experts in ASME SA240 stainless steel plates, Gangsteel offers reliable solutions. This guide details methods to check if stainless steel is 304 or 316, incorporating terms like ss 304 plate density and sa 240 304l material.

Why Differentiate Between 304 and 316 Stainless Steel?

304 and 316 have similar appearances but distinct properties. 304 is ideal for general corrosion resistance, while 316’s molybdenum enhances pitting resistance in saline or acidic conditions. Incorrect identification can lead to material failure in applications like sa 240 gr 304 pipe or sa 240 gr 316 plate. Methods include physical tests, chemical analysis, and documentation review.

Method 1: Magnet Test for Non-Magnetic Properties

Both 304 and 316 are austenitic, making them ss 304 non magnetic and non-magnetic for 316 in annealed conditions. Use a neodymium magnet:

• Procedure: Clean the surface of the sa-240-304 material or 316 item and place the magnet on it. If it doesn’t stick, it’s likely 304 or 316. If it sticks, it’s a magnetic grade like 430.
• Limitation: Cold-working (e.g., bending sa 240 type 304 304l) can induce slight magnetism, so this test isn’t definitive.

Method 2: Molybdenum Drop Test (Chemical Spot Test)

The presence of molybdenum in 316 (2-3%) is the key differentiator. A molybdenum test kit distinguishes:

• Procedure: Apply a drop of molybdenum reagent (available from suppliers) to a clean surface of sa240 304 stainless or 316. A color change (e.g., yellow or green) within 1-2 minutes indicates molybdenum, confirming 316. No change suggests 304 or sa 240 304l material.
• Accuracy: Highly reliable for sa 240 gr 304/304l vs 316, but requires proper handling of chemicals.

Method 3: Spark Test for Visual Identification

Grinding stainless steel produces distinct spark patterns:

• 304: Produces long, thin sparks with few forks, orange in color, due to low carbon in material sa 240 304.
• 316: Similar but slightly denser sparks due to molybdenum.
• Procedure: Use a grinder on a small area of sa 240 304 plate or 316 and observe spark characteristics.
• Limitation: Requires experience and comparison with known samples.

Method 4: Chemical Composition Analysis

For precise identification, use spectrometry (e.g., XRF or OES) to analyze composition:

• 304: 18-20% Cr, 8-10.5% Ni, no Mo.
• 316: 16-18% Cr, 10-14% Ni, 2-3% Mo. Labs can test sa240-304 material or sa 240 304h material for exact alloy content. Ss 304 plate density and sa 240 304l density are both 7.93 g/cm³, so density isn’t a differentiator.

Method 5: Check Certification and Labeling

Verify mill test certificates (MTCs) or labels:

• 304: Marked as UNS S30400, AISI 304, or sa 240 304 material.
• 316: Marked as UNS S31600 or AISI 316. Gangsteel provides MTCs for sa240 304l material and 316, ensuring compliance with ASME SA240.

Applications Where Identification is Critical

Correct identification is vital for:

• Marine: 316 for saltwater resistance in sa 240 gr 316 plate; 304 for freshwater.
• Chemical: 316 for acidic environments; 304 for mild corrosives in sa 240 gr 304 plate.
• Food: Both for hygiene in plat stainless 304 or 316.

Gangsteel’s SA240 Gr 304 and 316 are ideal for these uses.

Price and Availability Considerations

Ss sheet 304 priceand ss 304 plate price range $1,820-$3,584/MT, while 316 is $2,500-$4,000/MT due to molybdenum. Gangsteel offers competitive pricing for sa240-304 a240-304 and 316.

Why Choose Gangsteel for 304 and 316 Stainless Steel?

Gangsteel provides:

• Quality: Certified to ASTM A240.
• Customization: Sizes like plat ss 304 3 mm.
• Global Reach: Fast delivery for sa 240 tp 304/l.
• Variety: Including SA240 Gr 347 and SA240 Gr 904L.

Conclusion

Checking if stainless steel is 304 or 316 involves magnet tests, molybdenum tests, spark tests, or composition analysis. For what is sa 240 304 or sa 240 tp 304l, use certified suppliers like Gangsteel. Contact for UNS stainless steel plates.

FAQ

What is SA 240 304?

What is sa 240 304is ASME SA240 Grade 304 stainless steel.

What is the difference between 304 and 316?

304 is general-purpose, while 316 has molybdenum for chloride resistance.

What is SA240 material?

What is SA240is the ASME standard for stainless steel like sa240 ss 304.

Is 304 non-magnetic?

Yes, ss 304 non magnetic unless cold-worked.

What is the density of SA 240 304?

Sa 240 304 densityis 7.93 g/cm³.

What is the price of 304 stainless steel?

Ss 304 steel priceranges $1,820-$3,584/MT.