Stainless or Stainless Steel?

[ianinsa]

I have the ir gun type of thermometer (I first saw one at John Emerling's place) and some K type thermocouple units, and my son has an iPhone, well I have been astounded at just how inaccurate my stuff can be he,he. Alan you can get 1750deg C off eBay for about $100. The cheapies that are good for 400-500 degrees Celsius are about $20 and you'll be amazed as to just how many uses the can be put to. I love them for cooking.

[patrick]

From a metallurgists point of view 304, 316, 410, 420, 422, 440 (A, B, C) S32550, S32205, S32750 etc. are all types of stainless steels. The % of the various elements is widely different in each grade or grade family by they all are both stainless and they are all steel. The difference in scrap value is due primarily to the nickel content. The difference in function is that the 300 series grades are austenitic, which means they have very good ductility, even subzero temperatures. The 400 serials, most of which will transform to martensite, are not nearly as ductile, nor as costly. They can be made much stronger than the austenitc grades but they do not  have the same level of corrosion resistance as the austenitic family. The last group are Duplex grades which means they exist as combination of austenite and ferrite. They have very good corrosion resistance and strengths similar or somewhat higher than the 300 series but are less costly due to a lower nickel content.

[Alan Evans]

snip... Alan you can get 1750deg C off eBay for about $100. snip...

​I have looked a few times but I only ever found the 500˚ C or the £500 plus ones.

Are there any brand names for the $100 ones or are they generic?

Alan

[arftist]

If you can prove to then that it is indeed 17-4 or some other grade of stainless steel, they may pay more for it. As far as they are concerned though, magnets only stick to iron/steel. 

I brought in 20' of 17-4 4" shaft. Thought I had a payday. Magnet convinced them it was $.05/pound, not the $.55 I was expecting. Didn't unload, drove until I found a yard with a tester. Still didn't make big bucks but it was worth the drive. Yard cut a sliver off with a partner saw and paid for the test. Obviously they wouldn't be bothered for a small lot. 

[ianinsa]

Alan, I have bough off a chap via xxxxx xxxxxxx xxxx, I will PM you the info they have got lots of goodies and he will DHL them for you. I got one plus 3 more k type thermocouple units with digital readouts when I bought my last 20kw single phase induction heater (what a toy, ooh-yea!)

[SmoothBore]

I wasn't going to get into this topic, ... since it's basically irrelevant to all but Knife Makers.

But I'll point out a distinction that's been more-or-less overlooked.

 

Historically, there's been a distinction between "Nickle" steels, and "Chromium" steels.

Both of which are sometimes referred to as "Stainless" steel, ... but not always.

 

Beyond that, ... I'll second the notion that depending on the local Scrapper for technical information, ... is a bit risky. 

 

 

.

[patrick]

Smooth Bore- I did address that a few posts up. The 300 series grades are alloyed with much more nickel than the 400 series. That alloys them to be austenitic to very low temps and keep their ductility bu they are realatively  week. The nickel also aid in corrosion resistance. The 400 series lack nickel but are still stainless. Becuase they don't have the nickel they can be heat treated  to develop martensite. Good for wear resistance and edge retention. However, they are not as corrosion resistant as the 300 series materials because they lack nickel. But that also makes them cheaper.

17-4 is in a family of stainless steels which are called martensitic precipitaion hardening. They are low carbon, but do form martensite. Instead of tempering them to reduce hardness, you age them to allow copper based precipitates to form and add stress. This improves the hardness and strength. They are also in the low nickel catagory so corrosion resisitance is coming from chrome.