How to anneal aluminum rivets with steel

How can you harden steel?

What should we do if we want to harden the steel? First, we need to be aware that larger flames produce less heat and smaller flames produce more heat. Bubble burners only heat a small, very specific area. For larger steel elements, you have to work in a forge to heat the whole thing enough.

How can we harden the steel?

Some of us have probably asked ourselves this question several times - how can we safely harden the steel?

We should always wear glasses and gloves when operating a propane burner. Before starting the burner, we must read all the instructions to know how to use it safely and we must follow them carefully and faithfully. When working, we should always wear thick gloves to avoid burns.

On a metal or steel surface, for example, we can use an anvil to avoid the risk of fire. In the event of a fire, a class B fire extinguisher must be kept close by.

The best way to keep the steel directly on fire is with a non-dominant hand and metal tongs so as not to approach the fire. If we cannot hold the steel with pliers, we should place it on a larger refractory work surface. Let's use your dominant hand to heat the entire piece of steel before aiming the flame at the area to be hardened. We should always wait until the steel turns cherry red. The color of the steel should always be observed because it changes as the steel gets warmer. If the steel is shiny cherry red, about 760 ° C (1400 ° F), then it's hot enough to harden.

Cooling of the steel after hardening

After hardening, we should cool the steel properly. To do this, we move the heated steel directly into the coolant with pliers because it is still hot. If you have completely immersed the steel in water or oil, we should stay away because steam or splashes can form. We hold on to the steel so that we don't have to look for it later. Hardening the steel quickly cools it down so that the feet inside harden together. We should therefore wear thick gloves and a face mask before we harden and cool the steel so that water or oil does not cause skin burns. Remove steel from the extinguishing agent when the bubbles stop forming. Water or oil will continue to boil when heat is transferred from the steel. The steel must be completely submerged until there is no more steam or bubbles, which should only take a few minutes. When we're done, we'll put the steel on the work surface. Hardened steel is harder but becomes more brittle. We are not supposed to drop the steel and bend it after it has been freshly hardened.

Cleaning the steel after hardening

We should wipe off any hardness residue from the steel. Water is corrosive to steel and can cause damage if left on the surface. That is why we should always remember to wear gloves when using a cloth to dry steel completely.

How to harden and anneal steel

Preheat the oven to 191 ° C. Then wait for the furnace to heat up completely before we put the steel in. If we can't put the steel directly in the furnace, use a welding torch.

If the steel area is small, we can use a smaller oven or toaster. Place the steel directly on the oven grid or baking sheet for 3 hours. Let's let the furnace heat a piece of steel. During the process, the steel heats up so much that the feet in it become soft and less brittle.

If we have to use a burner then it is better to point the end of the flame at the area that you want to cure. Then we keep heating the steel until we notice a blue color on the metal. This means that the steel is hardened.

Cooling the steel

After heating the steel for 3 hours, we turn off the furnace and let the steel cool down overnight. This allows the steel to normalize and maintain its hardened structure. The next morning we take the steel out of the furnace. If we harden the steel with a burner then it is advisable to place the metal on an anvil or other large heat-conducting steel surface in order to avoid possible injuries or burns.

Hardening the steel in oil

Very often people ask how steel can be hardened in oil. This process is not that different from water quenching. The first question we should ask ourselves is what do we want to harden? If an element is large (e.g. a machete) and is heavily exploited (e.g. we will not machine anything, chop wood, undermine other elements, etc.) then oil is the right direction because the higher impact strength of hardened steel makes you lose something of their hardness. And if the element is a hand knife, in this case, water (30-40 degrees).

Which oil should be chosen?

How many people have so many opinions. Some recommend professional so-called hard oils, which cost more than 50 euros, but others say that ordinary rapeseed oil should be enough. We can also find information from other blacksmiths who also use synthetic motor oil.

Categories Metal Encyclopedia