Complete Guide to Stainless Steel Grades: 304 vs 316 vs 904L

Introduction

Stainless steel is one of the most versatile materials used across industries, from food processing to petrochemical plants. However, not all stainless steel is created equal. The grade you choose can significantly impact performance, longevity, and cost.

In this guide, we'll compare the most commonly used stainless steel grades — SS 304, SS 316/316L, and SS 904L — to help you make informed procurement decisions.

SS 304: The Workhorse

ASTM Designation: A240 Type 304

SS 304 is the most widely used stainless steel grade, accounting for over 50% of all stainless steel production worldwide.

Chemical Composition

Chromium: 18-20%

Nickel: 8-10.5%

Carbon: ≤0.08%

Key Properties

Excellent corrosion resistance in atmospheric conditions

Good formability and weldability

Non-magnetic in annealed condition

Temperature resistance up to 870°C

Best Applications

Food processing equipment

Kitchen sinks and appliances

Architectural trim and molding

Chemical containers

Heat exchangers

SS 316/316L: The Chemical Warrior

ASTM Designation: A240 Type 316/316L

SS 316 adds molybdenum (2-3%) to the 304 composition, dramatically improving resistance to chloride corrosion and chemical attack.

Chemical Composition

Chromium: 16-18%

Nickel: 10-14%

Molybdenum: 2-3%

Carbon: ≤0.08% (316), ≤0.03% (316L)

Key Properties

Superior resistance to chlorides and sulfuric acid

Better creep resistance at elevated temperatures

316L variant offers better weldability (low carbon prevents sensitization)

Pitting Resistance Equivalent (PRE): ~25

Best Applications

Marine environments

Chemical processing

Pharmaceutical equipment

Food processing where chlorides are present

Surgical instruments

SS 904L: The Premium Choice

ASTM Designation: A240 Type 904L

SS 904L is a super austenitic stainless steel with very high levels of chromium, nickel, and molybdenum, plus copper addition.

Chemical Composition

Chromium: 19-23%

Nickel: 23-28%

Molybdenum: 4-5%

Copper: 1-2%

Key Properties

Exceptional resistance to sulfuric acid

Outstanding pitting and crevice corrosion resistance

PRE > 36

Resistant to stress corrosion cracking

Best Applications

Sulfuric acid processing

Phosphoric acid production

Oil and gas (sour service)

Seawater cooling systems

Comparison Table

How to Choose

Budget-conscious, general use → SS 304

Marine or chemical exposure → SS 316L

Highly aggressive chemicals → SS 904L

Conclusion

Selecting the right stainless steel grade saves money in the long run by preventing premature failures and reducing maintenance. At Swastik Metal Industries, we stock all major grades and can provide material test certificates for every shipment.

Need help choosing the right grade? Contact our technical team for expert guidance.