[TheForge] Tempering and hardness

[Paul Novorolsky]

Thanks Saint, That about sums up what I found, and represents my total 
knowledge on the subject of Full Hard SS. What I'm hoping to find out is 
a little more detail, particularly about the use of the term "tempered" 
in this context. I'm still assuming that it was tempered first, and then 
hardened.

**Paul



On 12/5/11 11:12 PM, Saint Phlip wrote:
> http://www.upmet.com/301-full-hard.shtml
>
> "301 Full Hard differs from other forms of 301 offered by United
> Performance Metals in that it has been hard cold rolled to its full
> hard condition. This increases the metal's attractiveness for forming
> and increases its fatigue life. In its full hard condition, type 301
> stainless steel has a tensile strength of 185,000 PSI minimum, and a
> minimum yield strength of 140,000 PSI. The combination of hardness and
> toughness make it ideal for springs."
>
>
>
> On Mon, Dec 5, 2011 at 11:25 PM, Bruce Freeman<freemab222 at gmail.com>  wrote:
>> I am no expert either, but I've also done some reading on these
>> subjects.  You are correct about carbon steels and some alloy steels.
>> You harden them (typically after annealing) by heating them to red and
>> quenching rapidly.  You temper the glass-hard steel by heating to a
>> much lower temperature (as indicated coincidentally by the temper
>> colors) to reduce the hardness and increase the toughness. AFAIK,
>> steel is the only material that can be hardened this way.
>>
>> Someone else on this forum will have to elaborate on the metallurgy.
>>
>> SS is steel in that it is mostly iron, but it has so much chromium and
>> nickel (and other elements?) that its behavior can be quite different
>> from carbon steel.  There are more than one kind of SS.  I understand
>> some SS's can be hardened and tempered, but I'm not sure of that.
>> IIRC, the 300-series can only be work-hardened.
>>
>> But if you weren't forging SS, then SS was pretty much irrelevant to
>> the question. He might as well have spoken about copper or brass,
>> which you anneal by heating to red and plunging into water, and harden
>> by work-hardening (e.g., hammering or drawing through a die).  Try
>> THAT with tool steel and see how "soft" it gets!
>>
>> The effect of hardening and tempering, along with grain growth, can be
>> demonstrated fairly easily with a test piece, if you want to go to the
>> trouble.  I would have told this know-it-all to go fire up a forge and
>> try it himself if he didn't believe me.
>>
>> On Mon, Dec 5, 2011 at 9:59 PM, Paul Novorolsky<crosspein at sbcglobal.net>  wrote:
>>> During a public demonstration last weekend, I was explaining to someone
>>> about hardening and tempering in pretty general terms. When I said that
>>> tempering sacrifices some hardness for toughness, a spectator told me I
>>> was wrong. He pretty much said "No it doesn't, tempering makes it harder".
>>>
>>> I disagreed assuming he had hardness and toughness confused, stating
>>> that the heat treating charts for common steels show a reduction in
>>> hardness at various tempering levels. He continued to tell me I was
>>> wrong, because he had bought 100's of tons of "full hard stainless
>>> steel" and asked how I explain that material. I told him I had no
>>> knowledge of it, but tool steels will lose some hardness during
>>> tempering. He repeated that I was wrong. At that point I was agitated,
>>> and told him to do some research and he'll see that tempering does
>>> result in loss of hardness, at which time his wife seemed annoyed with
>>> him and dragged him out of our shop. (amusing in itself, as he was a big
>>> man)
>>>
>>> While I could have handled that a little better, probably by asking for
>>> a detailed explanation of the process used for "full hard stainless",
>>> which I'm sure he had no clue.
>>>
>>> Anyway, I'm looking for more education. When I got home, I did some
>>> research, but I'm still short on details. If I understood what I read,
>>> "full hard stainless" is tempered, and then maybe cold rolled to work
>>> harden back hardness. I'm not really looking for tremendous detail here,
>>> just an explanation "in blacksmith terms" about what this stuff is.
>>>
>>> I also came across a statement in one search that popped up that said
>>> that some alloys will become harder by tempering. Being an internet
>>> source and therefore dubious in my eyes, I tried unsuccessfully to find
>>> additional sources to provide some verification. (and then lost the link
>>> that had that statement in the first place). So question 2 is "are there
>>> steels that become harder by tempering?"
>>>
>>> It's been awhile since I read anything on metallurgy, and since I tend
>>> to use macro processes for my heat treating, I tend to forget a lot of
>>> the details, but I'm hoping there are a few bits of knowledge, or maybe
>>> rumors to be had from the list. Any help?
>>>
>>> **Paul
>>> ______________________________________________________________
>>> TheForge mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/theforge
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:TheForge at mailman.qth.net
>>>
>>> TheForge mail list group photo site is
>>> http://www.photoworks.com
>>> Login: blacksmithblacksmith at hotmail.com
>>> Password: anvil
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>
>>
>>
>> --
>> Bruce
>> NJ
>> ______________________________________________________________
>> TheForge mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/theforge
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:TheForge at mailman.qth.net
>>
>> TheForge mail list group photo site is
>> http://www.photoworks.com
>> Login: blacksmithblacksmith at hotmail.com
>> Password: anvil
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>
>
>