Annealing is cold rolled precision bright steel tube heated to the appropriate temperature, according to the material and the size of the workpiece using different holding time, and then slowly cooled, the purpose is to make the internal organization of the metal to achieve or close to the equilibrium state, to obtain a good process performance and use of the performance, or further quenching of the organization for the organization of the preparation. Normalizing is the cold rolled precision bright steel tube heated to the appropriate temperature after cooling in air, the effect of normalizing is similar to annealing, only to get a finer organization, often used to improve the cutting performance of the material, but also sometimes used for some of the less demanding parts as the final heat treatment.
Quenching is the cold rolled precision bright steel tube heating insulation, in water, oil or other inorganic salts, organic aqueous solution and other quenching medium rapid cooling. After quenching cold rolled precision bright steel tube becomes hard, but at the same time become brittle.
In order to reduce the brittleness of cold rolled precision bright steel tube, the quenched cold rolled precision bright steel tube at a suitable temperature higher than room temperature and lower than 650 ° C for a long time insulation, and then cooled, this process is called tempering.
Annealing, normalizing, quenching, tempering is the overall heat treatment of the "four fires", of which the quenching and tempering are closely related, often used in conjunction with each other, can not do without the other.
"Four fires" with the heating temperature and cooling mode of different, and evolved a different heat treatment process. In order to obtain a certain degree of strength and toughness, the quenching and tempering at high temperatures combined with the process, known as tempering. After certain alloys are quenched to form a supersaturated solid solution, they are kept at room temperature or at a slightly higher appropriate temperature for a longer period of time in order to improve the hardness, strength, or electrical magnetism of the alloy. Such a heat treatment process is called aging treatment.
The pressure processing deformation and heat treatment effectively and closely combined to carry out, so that the cold rolled precision bright steel tube to obtain a very good strength, toughness with the method known as deformation heat treatment; in a negative pressure atmosphere or vacuum heat treatment known as vacuum heat treatment, which not only can make the cold rolled precision bright steel tube does not oxidize, do not decarburize, keep the surface of the treated cold rolled precision bright steel tube is smooth and clean, and to improve the performance of the workpiece. Performance, but also can pass into the infiltration agent for chemical heat treatment.
Surface heat treatment is only heating the surface layer of cold rolled precision bright steel tube to change the mechanical properties of the surface layer of the metal heat treatment process. In order to only heat the surface layer of cold rolled precision bright steel tube without excessive heat into the workpiece, the use of the heat source must have a high energy density, that is, in the unit area of cold rolled precision bright steel tube to give a larger heat energy, so that the surface layer of cold rolled precision bright steel tube or localized can be a short period of time or instantaneous to reach a high temperature. Surface heat treatment of the main methods of flame quenching and induction heating heat treatment, commonly used heat sources such as oxyacetylene or oxypropane flame, induction current, laser and electron beam.
Chemical heat treatment is by changing the cold rolled precision bright steel tube surface chemical composition, organization and properties of the metal heat treatment process. Chemical heat treatment and surface heat treatment is different from the latter change the chemical composition of the surface layer of the workpiece. Chemical heat treatment is placed on the workpiece containing carbon, nitrogen or other alloying elements of the medium (gas, liquid, solid) in the heating, insulation for a long time, so that the surface layer of the workpiece infiltration of carbon, nitrogen, boron and chromium and other elements. After infiltration of elements, and sometimes other heat treatment processes such as quenching and tempering. Chemical heat treatment of the main methods of carburization, nitriding, metal penetration.
Heat treatment is one of the important processes in the manufacturing process of mechanical parts and molds. Generally speaking, it can ensure and improve the cold rolled precision bright steel tube of various properties, such as wear resistance, corrosion resistance, etc.. Can also improve the organization of the blank and stress state, in order to facilitate a variety of cold and hot processing.
For example, white cast iron after a long time annealing treatment can be malleable cast iron, improve plasticity; gears with the correct heat treatment process, service life can be doubled or dozens of times more than the non-heat treatment of the gears; In addition, inexpensive carbon steel through the infiltration of certain alloying elements with some pricey alloy steel performance, can replace some heat-resistant steel, stainless steel; molds and dies are almost all need to be After heat treatment can be used.