Metal Alloy Strength Comparison
Most of the tubing produced today uses 304 stainless steel as the alloy of choice due to its great combination of strength, ductility, price, and availability. 304 is a great starting point for many designs as it works for most applications. However, this alloy may not be optimal for the application and may require specialized processing to deal with the shortcomings of the material.
Inconel® 625 Stainless Steel
Inconel® 625 stainless steel, with a chromium-nickel and low carbon content, is used for its outstanding corrosion resistance especially at elevated temperatures. This alloy has similar physical properties and fabrication characteristics as Type 304 at room temperature. The unique chemistry of Inconel® 625 increases the corrosion resistance in salt water applications and against high temperature oxidation. In the medical field, it has served the MRI compatible market due to its high nickel content that keeps a low magnetic permeability even at high strengths. Inconel® 625 is more expensive than 304, but is readily available.
316/316L Stainless Steel
Type 316 /316L stainless steel, with its chromium-nickel and low carbon content, is a commonly used austenitic stainless steel. This alloy has similar physical properties and fabrication characteristics as Type 304. The addition of Molybdenum (versus 304) increases the corrosion resistance in salt water applications. The biocompatibility of this alloy has been well researched. This grade of stainless is an economical option and typically readily available. The lower carbon content in 316L grade increases resistance to intergranular corrosion following welding or stress relieving
304/304L Stainless Steel
Type 304/304L stainless steel, with its chromium-nickel content, is the most versatile and widely used of the austenitic stainless steels. No other grade of stainless steel comes in so many forms, finishes and used with such diverse applications. These grades can be severely deep drawn without intermediate annealing, which has made this grade the industry standard in the manufacture of drawn stainless parts. The lower carbon content in 304L grade increases resistance to intergranular corrosion following welding or stress relieving. These grades of stainless steel are the most economical and readily available.
MP35N® Alloy, with its nickel-cobalt-chromium-molybdenum content, has a special combination of high strength, ductility and corrosion resistance. In the annealed state, it has the same easy-to-work characteristics of the 300 series alloys, yet it is capable of being hardened by a simple heat treatment. It has higher tensile strength/hardness and even ductility compared to the 300 series when cold-worked. After the aging heat treatment, it has one of the highest strengths on any currently produced alloys. The unique properties of MP35N® allow for it to be used in applications where other alloys have failed.