Question: another steel question

[diane b]

I was reading Carl's (CRW) thread about steel and started this one so as not to hijack his thread. I don't understand what all the numbers (410, 416, 303, 304, etc.) mean. Scott (Pilguns) wrote, "303 and 304 are gummy...410 or 416 is preferred to cut." What is in the steel that makes it gummy? What in the steel makes 410 or 416 better for cutting? Glenn wrote,"...Mirinan prefers heat treated 416." and Fred Carter wrote, "416ss heat treated and tempered at 1100f engraves very well." What is the difference between heat treating and tempering? I have annealed metal - is this what is meant by "heat treating?" The metals I have worked in are copper, brass, silver, and gold. Steel is a new animal for me. I would appreciate any information or direction to threads in this website, other websites, books, magazine articles, etc. that could help me understand steel better, and what qualities make steel better for engraving. Thank you ahead of time for any help you can give me.
Diane

 

[Weldon47]

Diane,

The thread refers to stainless steel & the numbers are the type or grade. Chromium is added to carbon steel to produce stainless & the higher the percentage the more resistant to rust the steel becomes. In addition to chromium, there are other alloy elements as well, each of these affect the way the steel machines (which is what you are really doing when you engrave it). IMHO, higher chromium content steels tend to "gall" or tear instead of cutting smooth and clean like you are used to on the non-ferrous metals. A cutting lube will help this but may not totally eliminate it. A slight change to your graver geometry (face angel, heel, etc...) might help you along too.
Experiment with the different grades & see how they feel to you. It's not that big of a deal really once you get used to it! The worst thing is getting a hold of something that is barely soft enough to cut but way too hard to actually do your best work in....those are tough to get through!

Weldon

 

[Charlie]

Gee, heat treated steel is just that. Steel that has been mechanically modified with heat. The 400 series Stainless Steel which is heated to 1450º to 1550ºF and quinched in Oil, will become harder and stronger. Yet this harder and stronger steel might break more easylie because internal stresses will develope because of the quenching process. When the hardened steel is brought back up to a temperature of say, 1100ºF and held at this temperature for one hour, this is called tempering. This tempering process will soften the steel somewhat, but remove the internal stresses. Now the steel is hard, and tuff at the same time, and it is said; the steel has been heat treated.

300 series stainless is not heat treatable but it is corrosion resistent and tuff. Also, it is not friendly to cut.

Anealed steel, is steel that has been brought up to temperature in excess of 1400ºF and cooled slowly over a span of several hours. This annealing process will leave the steel, soft and stress free.

 

[monk]

truth be known, volumes of books be required to hold all the info neded to cover all the data on steel and its' alloys.crs, or cold rolled is just an advanced version of mild steel. it's a bit more dense, but quite engraveable. stainless alloys-- test with a magnet. if a magnet sticks, the piece will usually be able to be engraved. has less chrome and hard stuff in it.

 

[dhall]

Hi Diane,

Well, here's the uber-geek response. For more than you ever wanted to know about the composition of any number of materials, check out www.matweb.com. You can find out the exact differences between various alloys. The numbers are a short hand reference to different "recipes". Different performance characteristics are engineered into the alloys by adding/deleting various elements, and/or changing the percentages of the elements. Some alloys are better for casting, others for forging, others machining, others for welding, others for different properties as tools, etc. Kind of interesting in a background sort of way, but the experiential testimonials folks are offering up here are going to be of more direct value to you as an engraver.

Insofar as "heat treating" steel, there are 3 basic words/concepts that come into play, Annealing, Hardening and Tempering. There is some overlap between ferrous and non-ferrous metals, but there are some very distinct differences, so it can get confusing because some words used in both arenas can have slightly different shades of meanings or implications. There are also lots of nuances and exceptions to what follows, but as a general overview, in broad strokes, this is what goes on.

When people say "heat treating", they might mean all 3 steps, Annealing, Hardening and Tempering, but usually, what they really mean it to convey, is a combination of both Hardening and Tempering. Annealing makes the metal soft. How it does this is different between ferrous and non-ferrous metals, but the end result is that internal stresses are virtually eliminated, and at the end of the process, the metal is about as soft as it can be at room temperature. Hardening is self explanatory, but generally for steels, hardening ends up being too much of a good thing. It's possible, but very difficult to get steel hardened to the desired hardness in just one step. It usually gets too hard when it undergoes its hardening routine. Too much hardness results in a material that is brittle, and will readily break. To modify the hardness, the process of tempering is used. What happens is that as the brittleness is reduced, so is the hardness to a lesser degree, but the toughness is increased. Hardness is the ability of a material to withstand scratching or abrasion. Toughness is the ability of a material to withstand shock and breakage. You could make a razor blade and a hammer out of the same alloy (you wouldn't, but it is possible, for discussion purposes), but you'd want to harden and temper them differently. The thinness of the razor will allow some flexing, even though it really is quite brittle, but you need a razor very hard and not tempered to a great degree. Conversely, a hammer, because of the significant shock to which it is subjected, needs to be somewhat hard, but very, very tough. Same alloy, vastly different heat treating regimens.

All of this stuff goes on as a result of heating and cooling. The rate of heating, how hot, how long at a given temperature, the rate of cooling, how cold, what is used for heating, the environment in which its heated, what is used for cooling, etc., all of these things can come into play and have an importance in Annealing, Hardening and Tempering. There are internal changes that allow/cause all of this to happen that occur at a molecular level, and as Monk pointed out, many, many volumes describe the minutia of it all, but this should take some of the mystery and confusion out of what you're hearing/reading when it comes to this topic.

Good Luck,
Doug

 

[Weldon47]

Great explanation, Doug! Thanks for baring your "geekness" before us all!

WL

 

[diane b]

Thank you all for the education and taking the time to answer my questions.

Dear Weldon, You are so right. There is nothing like experimenting. A person needs to geth their hands into it to find out what works for them. Thank you for explaining about the chromium and how it affects the steel.

Dear Doug and Charlie, wow! Great information on heat treating: annealing, hardening and tempering. Very thorough information. I appreciate the link. Thank you

Dear Monk, There is nothing like having an easy rule-of-thumb when one is trying to evaluate something: if a magnet sticks, it's probably good for engraving - so easy! Thank you

I really appreciate the generosity of your information, as well as all those who are so willing to share their knowledge on this site. Thank you again.

Diane