Dongguan Lihua Machinery Equipment Co., LTD. gives you a brief explanation of the methods of quenching and their own advantages and disadvantages.
1. Induction heating surface quenching
: the workpiece is placed in the sensor, electrically heated, so that the surface of the workpiece is rapidly heated to the required quenching temperature, and then the water is sprayed onto the surface of the workpiece. The advantages are that it heats fast and even and is of high productivity. It can also prevent surface decarbonization and oxidation and reduce deformation. The disadvantage is that it requires quite complex electrical equipment.
2.Single liquid quenching: heating the steel to quenching temperature, and cooling in a quenching agent (water, salt water or oil), is called quenching. The advantage is that method is simple so it’s widely applied. The disadvantage is that the internal stress is large so the steal is prone to crack or deformation.
3.Double liquid quenching: cooling the heated steel parts in water or salt water first, and when it is cooled to a certain degree (depending on the material), transferring it quickly into the oil to cool, is called double liquid quenching. The advantages are that it can guarantee high hardness and reduce deformation and cracking. The disadvantage is that the technical operation requirements are high which means the time of the steel in the water must be strictly controlled .
4.Stepped quenching: Cooling the workpiece that is heated to quenching temperature in a bath or alkaline bath with a temperature slightly above or slightly below the Ms point, and keeping a certain time in the bath, then puting it in the air or oil to cool, is called stepped quenching. The advantage is that it greatly reduces the quenching internal stress making the deformation and the cracking tendency greatly reduced. The disadvantage is that it can only be used for workpiece with thickness or diameter not exceeding 8 -- 10mm.
5.Flame surface quenching: use oxyacetylene to heat the workpiece surface, and then quickly put it into water to cool it. The advantage is it’s economical and convenient and of high efficiency. The disadvantage is that the quality is not good, if not controlled properly, it’s easy to produce overburnt, decarbonization, the unequal and other defects.
6.partial quenching: It is relative to the above methods which are the overall heating quenching methods. Some of the artifacts only need partial quenching, such as calipers, only the claw needs hardness, then just heats the claw, the other part is not heated.