Better, Stronger, Cheaper; RA 253MA is Your Solution

As a follow up to the recent blog entry about creep strength and what that is, you might be wondering which alloys have better creep properties than others.  Typically, creep properties follow right along with alloys that have higher room temperature yield strengths which can be attributed (primarily) to elevated carbon and nitrogen levels.

Creep RuptureOne such alloy is RA 253 MA. For applications up to 2000°F, RA 253 MA is one of the strongest and most creep resistant alloys on the market; having average creep values similar to RA 602 CA at 1900°F and higher creep strengths than 601 up to 2000°F. You could take our word for it or let the picture below speak for itself.

This picture shows pieces of 16ga material fabricated into rings. During the test, the rings were subjected to 1800°F and left in the furnace until only one was left without visible creep. After 38 hours the 601 material finally gave out (however slightly) supporting the data that suggests RA 253MA has better creep properties at elevated temperatures. This test was run in the 1980’s in Sweden and I can personally say that this photo has not been altered as I have seen the rings and they look the exact same in real life as they do in the picture.

While RA 253MA is typically considered inferior to 601 due to the maximum  sustained operating temperatures in oxidizing environments; 2000°F for RA 253MA and 2200°F for 601; it is almost always considered an upgrade to 309 and 310 stainless steels. There are many benefits to using RA 253MA over 309 or 310 and the links below have the direct comparisons between 309, 310 and RA 253MA.

RA 253MA vs 309

RA 253MA vs 310

 

All of the grades that have been brought up in this post have been used for many similar applications; bar baskets, retorts, rotary kilns, heat treating fixtures and radiant tubes, to name a few. On one occasion, RA 253MA was implemented into a carbon electrode heat treating application where 309 had been used for years. The higher creep strengths in RA 253MA did not allow for as much distortion as the 309. Since then, other companies with the same application are beginning to test RA 253MA.

RA 253MA may not always be the best grade in all applications. However, when strength is one of the most important material properties, RA 253MA cannot be overlooked… especially when it is less than half the price of 601.

Tyler Reno