Austenitic Stainless Steels

You need a full course in metallurgy.

The pearlitic fine grain structure (of Normalizing) in Austenitic steel?

For alloying, in short you have

ferrite stabilisers (Cr, Si, W, V and Mo being the main)

Austenite Stabilisers (Ni and Mn are main with N and C being others)

For the last question it is available in ASM handbook.

For the first one you can refer to this

everything really depends on transformation temperature and nucleation elements. There should be a phase diagram for the metals that you are referring to. It would be your best reference.

If you are wondering why certain metals do not transform through certain phases, it's completely dependent on chemistry and the rate of cooling along with phase transformation temperature of each element.

This is the principle of all metallurgical design.

In this case solution annealed and normalizing have the same meaning. Quenching metals normally results in hardening. However; for austenitic stainless steels the opposite occurs, when they are quenched they anneal. Normalizing is a type of annealing that is usually done in air, but we want to trap the alloy in the austenite phase so cooling is rapid. To cool rapidly, and help prevent scaling, a salt solution (brine) is used. Hence the term "solution annealed" is applied.

As stated earlier the composition helps promote and sustain the desired crystalline phase and produce the austenitic, ferritic, and martensitic steels.

I have never seen creep temp. specified by ASTM which are the same standard specifications as ASME. ASME just adds a prefix letter, e.g. A 304 becomes SA 304. We do know that creep occurs at 30 to 40 percent of melt point.

Hi,

I always believed that "solution" stands for the high temperature achieved which is above the stability point of (mainly) chromium carbides. For that reason in some cases with non L grades if during manufacturing process the steel has been exposed to temperatures in the range of chromium carbide precipitation on grain boundaries, a "solution anneal" is required to eliminate the "sensitization" of steel to IG corrosion.

Kind regards

Kwetz, you are right.

Solution heat treat followed by rapid quench are; in fact, two different operations. I hope you'll agree that both are essential to producing a workable corrosion resistant austenitic. I was hoping to answer the part of the question referring to austenitic stainless steels not being normalized. I would not intentionally convey confusing or incorrect information.

Thank you for the correction

K is right- solution annealing is done at the temperature when the carbides move into the solution.

The cooling is done quickly (not always in brine solution, even some alloys are air blast cooled)

solution annealing is performed by heating the SS to approx 1050 -1100 °c this will dissolve the carbide and is important when the SS will be used in an enviroment where there is a potential for corrosion, is in contact with a corrosive solution.

Cr , Mo and other element are element that increase the ferrritic content while Ni, Mn, C increase the austenite content. if you look at the shaeffler diagram linked below you will see the effect of the different element:

http://www.nhml.com/i/resources_NHML_Martensite-Austenitic-Stainless_fig1_lg.gif

http://www.bssa.org.uk/topics.php

http://www.corrosionist.com/Stainless_Steel_grades.htm

S

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