What Does
Baking Mean?
Baking is a treatment method of steel products. This treatment method consists of heating surface layers of steel parts, which causes distortion in lattices. The heating of steel surface layers causes temperature differences between the surfaces and interior of parts, which ultimately reduces delayed fracture and hydrogen embrittlement.
This method of treatment is used to remove hydrogen infused during plating and other chemical processing. It can be used in stripping, chemical milling, pickling and etching.
Baking is also known as hydrogen embrittlement relief.
Corrosionpedia Explains Baking
Baking means heating a material surface in a furnace at a controlled temperature to remove gases and inhibit material fracture. A steel part has a higher susceptibility to hydrogen embrittlement because when it is manufactured it contains hydrogen in molten steel or hydrogen penetrates the surface during pickling to remove scale. Traditionally, steel parts are baked in a furnace for a few hours at 210-570°F (100-300°C) to reduce concentrations of hydrogen in steel parts. The optimum baking temperature for screws is regarded as 3630°F (2000°C).
Steel parts subjected to baking include:
- Screws such as wood screws
- Tapping screws
- Parts made of carbon steel or low-alloy steel such as:
- Bolts
- Pins
- Washers
- Plates
Duration of baking in a furnace depends on concentration of hydrogen or size of the parts. Generally, four hours are needed. When a batch-type furnace is used for baking, the productivity is reduced; the total stock and the facilities are increased. Also, when it is conducted in a continuous-type furnace, a long conveyor is necessary, causing higher production cost.
The baking furnace functions similarly to a heat-exchanger where “cold” air is sucked into the flues (pit-walls) and cools down the hot-baked anodes during anode production. The manufacture of a high-quality anode with good strength and electrical conductivity requires baking “green” anodes in a baking furnace.