The heat treat colors should come off somewhat easily, are you heat treating in foil or an inert environment? Try vinegar, sometimes it will take off the color effortlessly. If you need to grind it for a while to remove something isn't right, even a quick touch to the buffer should remove the color.
Full Answer
Is discoloration after heat treatment a problem?
The part was always bright after heat treating. In trying to minimize distortion, different heat treat options were being tried. The heat treater asked if discoloration was a problem. I asked my customer, he said no. The parts came back dull grey almost black appearance.
What is the best way to remove discoloration from the surface?
The electrochemical method is extremely effective in these cases since it successfully removes oxides from the surface and restores the anti-corrosive passive layer. Brushing and grinding can also remove discoloration but it is impossible to guarantee that proper (re)passivation will occur.
What is the best way to reduce scale in heat treatment?
A. For eliminating or substantially reducing scaling, anti scale compound may be used. Removal of anti scale compound after heat treatment is easy, and surface finish of component is good. Unproductive work of scale removal is either eliminated or substantially reduced.
How to remove the discoloration caused by welding?
Usually, discoloration involving lighter (yellow) shades is much easier to remove since it forms under the influence of lower temperatures during welding. Electrochemical method is extremely effective in these cases since it successfully removes oxides from the surface and restores the anti-corrosive passive layer.
How do you remove heat treatment scaling?
Common methods include “pickling” a part in aqueous acid solution, washing it in scale removal chemicals, electronic removal (via a process that's essentially the opposite of electroplating) and mechanical removal. Heat treaters typically prefer mechanical removal via blasting.
How do you remove tempered steel?
0:271:44Rebuild: The Skill That Helps You Drill Through Steel - YouTubeYouTubeStart of suggested clipEnd of suggested clipSolution spot annealing basically reverse heat treating that tool steel to get into the metal. YouMoreSolution spot annealing basically reverse heat treating that tool steel to get into the metal. You need to soften part of it you need to remove the temper.
Can you Unharden steel?
Place the steel in a heat treat oven or forge and slowly raise the temperature of the steel to its particular austenite region. The austenite temperature region is different for each grade of steel and can usually be found from the foundry that produced the sample of steel.
Can you Retemper steel?
No. The tempering reduces the amount of martensite and thus makes the steel softer. Heating it again to a lower temperature will not introduce additional martensite. The only way to do that is to heat it until the metal de-magnetises, quench it again, and then temper to the desired hardness.
What causes heat treat scale?
Scale is an iron-rich film that can form on a part once it reaches high temperatures in heat treatment or manufacturing settings where the atmosphere is not controlled. There’s no fixed temperature associated with scale formation because it’s very dependent on the elements making up a part.
Heat treat scale removal
Manufacturers and heat treaters each have their preferred scale removal methods.
Heat treat scale prevention
There are some instances, however, when heat treat scale prevention is recommended over removal. For example, tool steel and stainless steel parts are often best treated in vacuum furnaces that remove atmosphere from the chamber. With no atmosphere to react to, scale won’t form.
Plan ahead
Remember that scale formation represents an actual loss of material on a part. If you’re concerned that your specs don’t account for this loss, speak with your engineers about designing with scale removal in mind and whether it’s feasible to design with more scale-resistant materials.
How to remove heat tint from stainless steel?
Several methods are commonly used to remove discoloration on stainless steel after welding – electrochemical cleaning, chemical pickling, and mechanical grinding & brushing are just few of them. However, the choice of method depends largely on the scope of the problem.
What are some examples of heat tints?
Industrial terminology recognizes a variety of related terms signifying the same phenomenon – discoloration, oxide scale, and rainbow effect are just some of the popular examples.
What temperature does stainless steel change color?
The color combination depends largely on the amount of heat used during welding – darker colors (brown, blue, and purple) are usually formed at higher temperatures (> 370 °C or 698 °F). ...
Is discoloration easier to remove?
However, the choice of method depends largely on the scope of the problem. Usually, discoloration involving lighter (yellow) shades is much easier to remove since it forms under the influence of lower temperatures during welding.
Does Cougartron remove oxide scale?
Cougartron weld cleaners effectively remove all traces of discoloration. When it comes to low-powered systems, the process of removing the oxide scale can become more complicated. In certain cases, the use of various methods is necessary but electrolytic cleaning in most situations is the most appropriate solution.
What is the best way to remove mill scale?
Sulfuric acid is very common for removing mill scale. For heat treated and weld steel you may want to set up a small pilot tank with the following mixture: 18% by volume of 70% nitric acid. 6% by weight of ammonium bifluoride. 2% by volume hydrochloric acid. Temp. ambient.
Can you use an inert gas furnace to remove scale?
If you cannot afford to use an inert gas furnace to prevent the scale, but the production is too high to bag the nails & needles, and anti-scale compounds can't practically be applied, you'll have to chemically remove it as suggested.
Can you use hot alkaline cleaner to remove scale?
We've used hot alkaline cleaners for removing that kind of scale, and sometimes it even works. Pickling in hot, dangerous hydrochloric acid can also work, but I don't recommend it: you might remove the scale, and cause the part to crack from hydrogen embrittlement.
How to smother an onion in oil?
Quench the blade so that the entire edge goes in first followed immediately by full submersion. Hold the blade horizontally and move it down into the oil quickly as if you are chopping an onion below the surface of the oil. Quenching only takes a few seconds. Have a lid ready to smother a fire if the oil ignites.
How to temper a knife?
The following seven steps show how to use heat treatment to harden and temper your knife. If you are using a knife made from milled steel by material removal you can proceed straight through steps 1-7. If your knife was forged, normalizing is a good idea. To normalize repeat steps 1 through 3 three times letting the knife air cool between each ...
What is the purpose of dim lighting on a knife?
The goal is to attain an orange glow evenly spread along the blade, in particular on the cutting edge.
What is the chemical used to alter / reduce a component of, or the entire color, of a por
Bleaching. – a chemical used to alter / reduce a component of, or the entire color, of a porous gem. Some gemstones are bleached and then dyed, a form of “combination treatment.”. 1. The most commonly encountered bleached gems include:
Why is jade bleached?
Bleaching in jade is typically part of a two-step process: because acid bleaching causes the material to become slightly porous or susceptible to breakage along fractures, it is then subsequently treated with polymer impregnation to fill these open spaces to produce a better overall appearance.
What is surface coating?
– altering a gem’s appearance by applying a coloring agent like paint to the back surfaces of gems (a treatment known as “backing”), or paint applied as a coating to all or a portion of a gemstone’s surface with the effect of altering the color . 1.
Why do pearls need dye?
Pearls – Dye often improves the appearance of lower–quality natural and cultured pearls by enhancing their color. Many pearls seen in the market are dyed, as the bottle of dye-soaked pearls (left) shows, and the single pearl demonstrates (right).
Is a gemstone treatment permanent?
Non-disclosure of this treatment could cause a person to believe that a particular gemstone was of higher quality naturally and therefore be more valuable than it actually is. An added challenge is that treatments can be permanent, long lasting, or short-lived under normal jewelry use.
Can you remove dye from a gem?
Many dyes can be removed if the gem comes into contact with a solvent such as alcohol or acetone. Some dyes are unstable with exposure to the ultraviolet in sunlight and can fade over time. 3. Detectability –A qualified gemologist can detect dyed gems in most cases.
