DIY, craft, materials, and such / Metal notes

From Helpful
Revision as of 15:55, 17 July 2023 by Helpful (talk | contribs) (→‎Common metals and metal alloys)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search

Common metals and metal alloys


This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

The name doesn't describe what happens to the metal, but the typical way this is done: you set up an electrolytic cell (chemical reaction from an external electrical source), where the metal to be treated is the anode.

It's effectively intentional, controlled corrosion to form a thick oxidized layer.

It's mainly done to create a protective layer, that tends to be more abrasion resistant, though there are also aesthetic reasons, like a uniform finish that can be dyed.

It is perhaps most used on aluminium alloys, but applies to various other metals as well.

Soldering, brazing, and welding

This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Soldering often refers to soft soldering - for electronics and sometimes craft.

Such solding puts a filler metal between two metals, where the filler has a (often much) lower melting point than the metal it's put on.


Copper, silver, and gold are probably easiest to solder to.
Iron, steel, nickel are not as easy, but doable.
Stainless steel and aluminium tend to be harder yet (largely due to their oxide layer(verify)).
Cast iron and some high-carbon steels won't really solder at all - but plating on them may be

These days, soldering is perhaps best known soldering electronics, where you have copper traces, and usually tin-plated leads, and because these are small and you need fairly little filler (the solder), you also need relatively little heat.

The solder used for this was often a tin-lead mix that melts around 180°C (varying with mix), while newer lead-free solders melt around 220-250°C (varying with mix).

For more practical details on soldering in electronics, see Electronics_project_notes/Common_terms,_useful_basics,_soldering#Soldering.

Soldering in metal plumbing requires more heat to work well, largely just because the pipes you're soldering act as heatsinks. This is part of why propane or even acetylene are common in this use, as they let you add heat faster and get things done before the heat spreads.

Before electricity, soldering used a chunky bits of metal (often copper) that was hammered into a widge-like shape, held in a fire, and useful for a short while due to its thermal mass.

Brazing seems to be defined mostly as working with fillers with higher-than-soldering melting points, higher than 420°C - or a bit higher, depending on who you ask.

So while you could say you can solder things like aluminium and it just requires much higher temperatures, you'ld probably call that brazing.

Aluminium needs higher temperatures in part because of the different filler material (involving aluminium itself, which melts at 660C), and also partly for the same soldering in plumbing is nontrivial: you're working on often-larger pieces of metal so it's hard to keep the working area hot enough without heating all of it.

(somewhat confusingly, you can also weld (most) aluminium, though this works differently)

Also, what some call hard soldering (often copper/silver) is often technically a form of brazing.

Welding refers to cases where

instead of relying on filler to fill the gaps between two metals're melting the existing metals so that they coalesce -- moxing something in is optional but sometimes a good idea

While you can weld without adding something, adding a little material can help there to be enough metal to melt together.

The filler is also part of this coalescing, so the filler metal type must fit the metal you're welding.

The coalescing is why (when done correctly) welding is typically stronger than soldering or brazing - it basically becomes the same piece of metal (...if only at the joint edges, and with some metallurgic footnotes relating to that heat changes metals).

Note that "makes two solids meld into each other"

  • also includes welding in a forge, which is fine for small pieces and softer metals but unwieldy for anything large, or for stronger metals.
  • is mostly associated with metals, but the description also applies e.g. to some plastics, mostly thermoplastics.
For example, what we call PVC glue is not glue but a solvent, that dissolves the surface of two PVC parts before you push them together. It would be more accurate to call this something like "PVC solvent welding".

See also:


This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Welding coalesces to pieces of metal by melting both pieces. Adding something is often optional. See above for a broader comparison.

Arc welding

Arc welding[1], using electricity, is probably the most recognizable subgroup, in part because it is generally less expensive, and less involved (how does a pressure relief valve work exactly - and who wants tanks of explosive gas when they can avoid it and/or there are careless dorks nearby).

Arc welding still groups a number of techniques.

Most arc welding variants involve a shielding gas somehow, because something that hot will oxidize easily (typically with air's oxygen), which is something you want to prevent at least while working on it (because it makes the weld pool harder to work with, and weaker).

Where exactly that gas comes from is one of the things that varies with the type of welding.

For attempted completeness
This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

The most used seem to be(verify):

  • Gas Metal Arc Welding - GMAW, a.k.a. MIG
  • Gas Tungsten Arc Welding - GTAW, a.k.a. TIG
  • Shielded Metal Arc Welding - SMAW, a.k.a. 'stick welding', manual metal arc welding (MMA/MMAW)
  • Flux Cored Arc Welding - FCAW

For more completeness:

  • Gas metal arc welding (GMAW) [2]
consumable electrode - a wire fed through the gun with a motor
a shielding gas feeds through the welding gun, from a bottle
technically groups two techniques where the welding gun supplies a consumable electrode, and a shielding gas
Metal Inert Gas (MIG) or Metal Active Gas (MAG) indicates the type of shielding gas
Inert is often argon and helium, an option only really used for nonferrous welding, such as aluminium
Active (mixtures of argon, carbon dioxide and oxygen) and are necessary for proper workings on ferrous/steel welding
often DC (and postitive polarity), sometimes AC

  • shielded metal arc welding (SMAW), sometimes stick welding, or MMAW / MMA (Manual metal arc welding) [3]
electrodes are consumable sticks
...that are coated with flux, which on use release vapours that act as shielding gas, and provides a layer of slag, both of which help against contamination while you work
making it one of the simplest and most portable variations (no gas bottles) and the easiest to get started with
one of the downsides is that you consume the electrode relatively quickly, and have to stop to replace it
electrodes need to be stored/used dry, because moisture messes up the flux (one reason for putting the flux on the inside - see FCAW)
  • Flux(ed)-cored arc welding (FCAW / FCA) [4]
similar to SMAW in many ways
flux from the consumed electrode usually enough for shielding (though in some situations external shielding gas is used for FCAW)
both count on gas, and slag, to protect during welding
both add some filler to work
both can be DC or AC
FCAW puts the flux on the inside, where environment moisture can't easily get to it
FCAW feeds a wire through
can be more productive than continuously replacing sticks (and can help lower slag entrapment defects where continuing welds)
SMAW equipment is cheaper, and is easier on more materials

  • Gas tungsten arc welding (GTAW), a.k.a. Tungsten inert gas (TIG) [5]
welding gun is a head that provides an nonconsumable electrode, and feeds the protective gas
separate filler rods
harder to do than than GMAW, and more expensive, but can be more controlled, can be stronger, and can handle more materials


  • Plasma arc welding (PAW) [6]
much like GTAW

  • Submerged arc welding (SAW) [7]
blocks contaminants by arcing submerged in a layer of granular flux.
makes sense in industrial settings

  • Electroslag welding (ESW) [8]
  • Electrogas welding (EGW) [9]

Resistance welding, Spot welding

Non-arc welding
This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.


  • Gas welding
    • often oxyfuel/oxyacetylene [10]
  • Resistance welding (ERW) [11]

  • Energy beam welding
    • laser beam welding (LBW) [13]
    • electron beam welding (EBW) [14]
  • Solid-state welding [15]
    • Ultrasonic welding [16], of plastics but also metals
  • Forge welding [17]
    • ...Historically