Navigating the various grades of stainless steel can be confusing. The term "stainless" simply implies a chromium content of at least 10.5%. The specific micro-structure and added elements dictate the final properties. Here is a breakdown of the three most common grades we manufacture at Rama & Sons.
Austenitic Stainless: 304 and 316
These belong to the 300-series. They are non-magnetic (or very slightly magnetic after cold working) and cannot be hardened by heat treatment.
- SS 304 (18/8 Stainless): Contains 18% chromium and 8% nickel. It's the most common general-purpose stainless grade, offering good corrosion resistance. Used widely in food processing and general industry.
- SS 316 (Marine Grade): Similar to 304, but with the addition of 2-3% Molybdenum. This vastly increases its resistance to chlorides (saltwater) and harsh industrial chemicals. Essential for marine hardware and pharmaceutical applications.
Martensitic Stainless: 440C
This belongs to the 400-series. Unlike the 300-series, it IS magnetic, and crucially, it CAN be hardened by heat treatment.
- SS 440C: Contains high carbon and high chromium. Once heat-treated, it achieves the highest hardness, wear resistance, and strength of all stainless alloys (up to 58-62 HRC). However, its corrosion resistance is lower than 304/316. It is the premier choice for stainless steel ball bearings and valve components where both wear and moderate corrosion are factors.
Always specify the exact grade required for your operating environment. Contact our metallurgical experts for assistance.
