Hardenable SS

[ozzie34231]

I'm wondering if stainless steel is hardenable in a home shop. What series? Where can I find temperatures. I have a controlable electric furnace. (1100 C).

Is 303 "case hardenable"?

Thanks,
Jerry

[fkaCarel]

The types are 403, 405, 406, 410, 414, 416 and 420. They have all Chromium in the region of 11%-14%. C is 0.15%, in 405 0.03% and 420 0.2-0.45%. 405 has 0.10-0.30 Al, 406 3.5%-4.5% Al, 414 1.25% Ni, 416 max 0.8% Zr. They have a ferritic-martensite structure. At 1000C 100% transfer to the austenitic fase. Max hardening with fast cooling. Structure is then hard brittle martensite. Description applies for 410.

As the 300 series have a max C of 0.06% they are not hardenable.

[ozzie34231]

Thanks for your quick reply. So after heating 410 through to 1000C and quenching, can I then temper it. What Approx temps?

Re: the 303, will "Kasinit" create a case hardening? I'm making tiny vise jaws and case hardening would give me a hard surface and a tough center. ( I think )!

Many thanks,
Jerry

[fkaCarel]

Re Tempering, my book says glowing out at 730C, which makes sense. But maybe this phrase will help:

"Material difficult to weld because of hardening. Preheat at 250C necessary, glow after welding at 730C during 4 hours per inch thickness. Cool slowly till 600C (30C per hour), after that cool in air."

The 303 is as far as I know a stainless with additions for machining. I think you refer with "Kasinit" carbonising the surface. As Chromium is more prone to absorbing the carbon you will get problems with Chromium carbides, intercristalline corrosion. Just rereading this stuff you will see that the 300 series have 18% Chromium and 8% Nickel and the hardenable 400 14% Chromium. This 4% difference is if I remember clearly, the solution to make hardening of stainless possible. The surgical stainless. I see no reference to Nickel and Carbon.

[Bud Guitrau]

I agree with fkaCarel about the 400 series. When a higher hardness in a stainless steel is needed, 440C is used. With its higher carbon content, (approximately 1% compared to about .4% carbon in 420 and 440), 440C can attain the highest hardness (60Rc) of any standard grade stainless providing higher abrasion resistance.

Another common tool steel grade of stainless is AISI 17-4 PH, with 17-4 signifying up to 17% chrome and about 4% nickel. The PH suffix designates that this is a precipitation hardening steel (also called age-hardening). Both terms are accurate descriptions because unlike the high heat and rapid quenching in oil or water of other steels, this steel is raised to only 925°-1050°F (within the range of your furnace) and held at that temperature for one hour per inch of thickness and then slowly cooled (aged) to room temperature. During the cooling period the structure undergoes a phase transition that precipitates the austenite into martensite producing hardnesses up to 48Rc depending upon the aging temperature.

Since 17-4 age-hardens at comparatively low temperatures, there is no distortion, but unlike most tool steels that tend to grow slightly during hardening, 17-4 will shrink enough to necessitate shrinkage allowances, especially in larger or longer parts. If aged at less than 1000°F, it will shrink up to .0005” per inch. When aged at 1100°F and higher, up to .001” per inch must be allowed.

Good luck!

Bud

[ajl6549]

Originally Posted by ozzie34231 Thanks for your quick reply. So after heating 410 through to 1000C and quenching, can I then temper it. What Approx temps? Re: the 303, will "Kasinit" create a case hardening? I'm making tiny vise jaws and case hardening would give me a hard surface and a tough center. ( I think )! Many thanks, Jerry

Why 303 SS for vice jaws? 8620 case hardened, or 4140 etc.

[ozzie34231]

The jaws need some degree of corrosion resistance

[ozzie34231]

BTW Thanks to all, for your replies.
Jerry