METALLURGY 101 - Different Steel Definded

[Scratch]

I started this thread on another forum and I think it would be good to have on this forum also. I know when I first started, I didn?t know the difference between HR and CR steel and didn?t want to look like an idiot so I did some research. If you have any input, or info on any other common types of metals, post it up here and I?ll keep editing this first post so the good stuff is at the top of the thread.

MILD STEEL-not aluminum, not copper, not stainless, just regular old magnetic, steel that'll rust.

A-36 STEEL- Is a standard steel alloy which is a common structural steel used in the United States. * Plate * I-beam * Pipe * Bar * Sheet are some of the forms it is made in. Steel seems to have an inconsistent numbering scheme. Sometimes it's as above, where the number is somewhat descriptive. Other times I think it's just a spec number. A-36 specifies minimum yield strength, not hardness. So it could have more carbon than mild, if that's what was in the soup when they made it.

AR STEEL - Abrasion Resistant Steel Plate (AR Steel Plate) with superior forming, welding and wear characteristics. This steel plate, with it's high Brinell Hardness ( BHN ) ratings, is particularly suited to the mining equipment, earth moving equipment, ore and aggregate processing, road building equipment manufacturing and fabrication industries, and rifle range silhouette targets, target backstops and bullet trap applications. Hardening agents such as carbon and manganese are used in the make-up of AR Steel Plate. Standard AR steel plate grades are AR200, AR400, AR500, and AR600 with the higher the number, representing the higher BHN rating.

COLD ROLLED STEEL- formed cold using pressure to force the steel down to the size wanted. It has a tighter grain, therefore Harder than HOT ROLLED STEEL, and is good for machining. It also has much closer tolerances than hot rolled. Hot rolled rounds are not exactly round, cold rolled is. If it matters use cold, if it doesn't, use hot & save the money.

HOT ROLLED STEEL- steel created and formed using a process that puts a layer of "mill-scale" on the surface of the steel, that among other things, acts as a pretty good rust preventative. It is worked into shape by roll forging. Shaping at a red temperature so it is easier to shape. and less pressure is needed. Also not quite as hard as COLD ROLLED STEEL.

PICKLED AND OILED- (P&O steel) Hot rolled steel that is oiled as a rust preventative that is much easier to remove than mill scale. Pickling is a treatment of metallic surfaces in order to remove impurities, stains, rust or scale with a solution called pickle liquor, containing strong mineral acids, before subsequent processing, such as extrusion, rolling, painting, galvanizing or plating with tin or chromium. The two acids commonly used are hydrochloric acid and sulphuric acid. Pickling liquor may be a combination of acids and may also contain nitric or hydrofluoric acids.
Oiling is the rust treatment.

SHEET STEEL- any of the steel formed into big flat sheets like sheets of plywood. Sheet steel is rated for thickness. This is by the gauge number rather than the fractional thickness.

PLATE STEEL- Plate steel is rated for thickness. This is by the fractional thickness rather
than the gauge number. Plate starts at 3/16"

IRON- Is too soft to hold an edge or shape in its pure form. It is combined with other materials to form other materials that are better worked.

CAST IRON- It is an iron alloys containing 1.8?4.5% carbon. Cast iron usually is made into specified shapes, called castings, for direct use or for processing by machining, heat treating, or assembly. In special cases it may be forged or rolled moderately.

WROUGHT IRON- Wrought Iron was created from bloom steel. It came out of the blooms as a lump of molten steel. This blob was hammered into shape to refine it and drive out the impurities. It was wrought, hence the name wrought iron. It has a grain to it almost like wood. It was much easier to forge weld than modern hot rolled.

DAMASCUS STEEL- Damascus got its name from the Damascus region in the middle east. Not because it was made there, but because it was a trading center and was sold there. The proper modern name is pattern welded steel. Usually layers of a high carbon steel are stacked with a lower carbon steel and forge welded together. After they are welded various things can be done to the billet to create a pattern. (twists, holes drilled, slots cut etc) When you then grind a knife blade on an angle it reveals different layers and the pattern. You also need to etch the steel is some type of acid so that the variations in metal show up. The high carbon doesn't etch as easily as the low, so you get purty purty patterns. I recommend a book called, The Pattern Welded Blade, by Jim Hrisoulas. What I just wrote is the most basic explanation. He covers it well and shows how to create various patterns. It is a great book by a true master of the craft.

GALVANIZED STEEL- is the process of coating iron or steel with a thin zinc layer, by passing the steel through a molten bath of zinc at a temperature of around 860 ?F (460 ?C). When exposed to the atmosphere, pure zinc reacts with oxygen to form zinc oxide, which further reacts with carbon dioxide to form zinc carbonate, a dull grey, fairly strong material that stops further corrosion in many circumstances, protecting the steel below from the elements. This known as Hot dip, there is a Cold dip which doesn't give as strong bonding or protection but is a cheaper process.

TOOL STEEL-Any of various steels capable of being hardened sufficiently so as to be a suitable material for making cutting tools. Contains materials that make it a good performer for cutting, and shaping other materials. Also called High speed steel.

STAINLESS STEEL- Any of various steels alloyed with at least 10 percent chromium and sometimes containing other elements and that are resistant to corrosion or rusting associated with exposure to water and moist air.

[elkriverfab]

Scratch,

Thanks for the info.

That's nice info to have in one location.
It answered a few questions I was wondering about.

Thanks.

[parrotlady]

Thanks Scratch! That is good info... I am afraid to confess that I thought mild steel was cold rolled steel... I probably could have saved quite a few dollars if I had bought mild steel instead of cold rolled to practice on... Live and learn

[AnotherDano]

Thanks Scratch! That is good info... I am afraid to confess that I thought mild steel was cold rolled steel... I probably could have saved quite a few dollars if I had bought mild steel instead of cold rolled to practice on... Live and learn

Don't let the terms cross you up, April.
Mild steel can be formed hot or cold.

Think of a sheet cake, layered cake and a bunch of cupcakes. They are formed differently, but they are all just cake.

The term Mild steel differentiates between it and the hardened steels that come in many grades.

(That's my understanding,,, Someone smarter than I may come along with a correction).

[peepers]

Thanks man. Thats is good information, wish I had it years ago.