How to make the metal heat treatment for castings in China？

Metal Heat treatment is the heating of metal materials to a certain temperature and heat preservation for a certain time,then cooled at the set temperature finial obtain the desired mechanical properties’s metal hot working process.

Metal Heat treatment process mainly includes heating, heat preservation, cooling three processes, sometimes only heating and cooling two processes,but these processes are interconnected and uninterrupted. Heating is one of the important processes of heat treatment. Dandong Iron Casting Group mainly uses liquid gas fuel furnace and electric furnace heating,Including  well furnace, box furnace, vacuum furnace and gas furnace.

It is always difficult to control heating temperature and cooling rate during heat treatment,heat treatment engineers need sufficient practical experience and rigorous quality control programs.Fortunately, our foundry can independently complete casting, heat treatment and machining processes in  our own workshop,so it will make it easier to control castings quality and delivery time.

Metal heat treatment process is mainly divided into three categories: integral heat treatment, surface heat treatment and chemical heat treatment.However, depending on the heating medium, heating temperature and cooling methods, each large category can be distinguished into several different heat treatment processes,the same metal can obtain different microstructure and mechanical properties when using different heat treatment processes.Iron and steel are the most widely used metal in industry, and the microstructure is the most complex, so there are many kinds of iron and steel heat treatment processes.

Overall heat treatment is to heat the workpiece as a whole and then cool it at an appropriate rate,to change the overall mechanical properties's Metal heat treatment process. Steel and iron overall heat treatment has four basic processes: annealing, normalizing, quenching and tempering.

Annealing is to heat the workpiece to the appropriate temperature, using different holding time according to the material and workpiece size, and then slow cooling,finial make metal internal organization close to equilibrium,obtaining good mechanical properties and preparation for further quenching.

Normalizing is to heat the workpiece to a suitable temperature and cool in the air,and normalizing effect is similar to annealing.It's just getting finer tissue and improving cutting performance of low carbon materials.

Quenching is to heat the workpiece after heat preservation, in water, oil or other inorganic salts, organic aqueous solution and other quenching medium rapid cooling.The steel parts become hard but brittle at the same time after quenching,to reduce the brittleness of steel,Heat the quenched steel at an appropriate temperature above room temperature and below 650℃ for a long time before cooling,this process is called tempering.

In order to obtain certain strength and toughness, the process of combining quenching and high temperature tempering are called quenching and tempering.Surface heat treatment is only heating the surface of the workpiece,to change the mechanical properties of the metal heat treatment process.The main methods of surface heat treatment are flame quenching and induction heat treatment,use of heat sources such as oxygen acetylene or oxypropane flame, induction current, laser and electron beam.

Chemical heat treatment is a metal heat treatment process by changing the chemical composition, structure and properties of the surface layer of the workpiece.The main methods of chemical heat treatment are carburizing, nitriding and metalizing.