Quench Hardening Stainless Steel, Does It Work?

In this video, Mal and Stephen explore the idea of quench hardening of stainless steel blades.

[@bjornSE]

Thanks for making this, very well explained and the practical demonstration helps a lot too!

[@mathieulapointe1207]

Great explanation 😊 thanks

[@hopefullysoonaweldingengineer]

Very informative video thank you. How formability of material will chance as the grains grow? As irregulary arranged grain boundry atoms pass into the grains the whole formability of the metal should increase because of slip planes may increase. Am I wrong?

[@khotsokeyho5525]

How do we get stainless steel harder?

[@TheZoneTakesYou]

work hardening should introduce dislocations and make granular movement more difficult -> harder

[@m.a.farrokhzad1962]

Some grades of stainless steel can get harder by adding alloying elements such as copper followed by a special heat treatment known as precipitation hardening (PH) which allows formation of hard intermetallic compounds within the steel. Example 17-4 PH steel which has added copper. Plain ferritic stainless steel has low carbon content but by adding upto 1% carbon which can transform it to martensitic stainless steel series which are hard.

[@MushookieMan]

What would be the hardness of a single crystal stainless piece compared to ordinary stainless made of grains? And what about metallic glass?

[@everydaymaterials9830]

To measure microstructure hardness and depending on the size of grain, Vickers microhardness or for smaller grains Atomic Force Microscopy (AFM) can be used.

[@fishdude666ify]

I've got a stainless bar someone gave me, no idea what kind; I've quenched it in oil and it was so freaking hard brand new resin disks wouldn't touch it. It was like grinding on titanium.

[@everydaymaterials9830]

Perhaps it is martensitic which has close to 1% carbon id can be quenched hardened, For this video we had ferritic stainless steel which has low carbon (less than 0.2%) which doesn't produce sufficient martensite after quenching and therefore can't be hardened.

[@Hello-ts5kh]

@@everydaymaterials9830 jus for some clarification you don’t need 1% C to make a stainless martensitic. 403/410 type stainless steels are commonly used martensitic grades in the power industry and often have C contents below .15%. My company buys annealed 403 forgings that as received measure around 80 HRB and will quench harden to about 44 HRC with only .12% C.

[@john-michaelrobinson3994]

Why did you quench it in water rather than oil?

[@everydaymaterials9830]

quenching in water provides a greater hardness than quenching in oil. Our goal was showing quenching will not increase the hardness of stainless steel.

[@rizkiezeddin6071]

Is there any way to regain the hardness? And also based on the phase diagram you showed us that stainless steels with 16-18% chromium will always be in ferritic state regardless of tempeprature change below 1500c, however I check for SS316 stainless steel contains about 16-18% Cr but is considered austenitic stainless steel. Am i misunderstanding anything?..

[@Hello-ts5kh]

That diagram is not accurate for 3XX series steels because they have large nickel additions which increase the size of the austenite phase.

[@john-michaelrobinson3994]

What about Chromium carbides?

[@everydaymaterials9830]

Time is a factor for producing Chromium Carbide (CrC) precipitation. Water quenching a think blade is fast heat loss process and does not produce much CrC. However, for thicker blades, CrC precipitation is a possibility.

[@phillipdridge9775]

And i still dont know how to harden stainless....

[@everydaymaterials9830]

Perhaps look into carburizing process for SS or other surface hardening methods listed in here: www.worldstainless.org/Files/issf/non-image-files/PDF/Euro_Inox/Surface_Hardening_EN.pdf

[@phillipdridge9775]

@@everydaymaterials9830 thank you very much ❤️

[@phillipdridge9775]

@@everydaymaterials9830 thank you very much ❤️