xiehe model

There are many commonly used follow-up processes, such as heat treatment, surface treatment, etc. These processing techniques are used to make precision parts more practical.

Heat treatment includes three stages of heating, heat preservation and cooling. The main factors affecting heat treatment are temperature and time.

Heat treatment is to heat the solid steel to a certain temperature, carry out the necessary heat preservation, and cool it to room temperature at an appropriate speed, so that the internal structure of the steel changes, so as to obtain the required properties.

In CNC precision parts processing, heat treatment is to improve the mechanical function of mechanical parts and ensure that the processing quality meets the needs of commodity use.

First of all, we need to understand how many methods are included in the so-called heat treatment in the processing of parts? In view of the frequency and importance of various methods in the process of processing, we choose the following type of analysis, that is, focus analysis.

During machining, we use the four most heat treatment methods: annealing, normalizing, quenching and tempering. Let's analyze them one by one.

Annealing

Definition of annealing treatment:

A metal heat treatment process in which metal parts are heated to a certain high temperature, kept for a period of time, and then allowed to cool naturally.

Its main function:

1. Reduce the hardness of the parts and improve the cutting performance

2. Eliminate the residual stress of the parts, stabilize the size, and reduce the probability of deformation and cracks

3. Refine the grains, adjust the structure, and eliminate the defects of the material structure

4. Make the material organization and composition uniform, improve the material properties or prepare the organization for the subsequent heat treatment process

Normalize

Definition of normalized processing:

Heat the metal parts to a certain high temperature, keep them for a period of time, and then let them cool in the air by spraying water, spraying, air blowing, etc. Different from the annealing treatment, the cooling speed is faster, so the obtained material structure needs to be more fine, the mechanical properties should also be improved.

Its main function:

1. Remove the internal stress of the material

2. Reduce material hardness and increase plasticity

Quenching treatment

The definition of quenching treatment:

Heat the metal parts to a temperature above the critical temperature Ac3 or Ac1, keep it for a period of time to make it fully or partially austenitized, and then rapidly cool below Ms at a cooling rate greater than the critical cooling rate for martensitic transformation heat treatment craft.

Its main function:

1. Significantly improve the rigidity, hardness, wear resistance and fatigue strength of parts

2. Physical and chemical properties that meet the ferromagnetic and corrosion resistance properties of some special steels

Tempering

Definition of tempering treatment:

It refers to the heat treatment method in which the hardened or normalized steel is soaked at a temperature lower than the critical temperature for a period of time, and then cooled at a certain speed to increase the toughness of the material.

Its main function:

1. Eliminate the residual stress generated when the workpiece is quenched to prevent deformation and cracking;

2. Adjust the hardness, strength, plasticity and toughness of the workpiece to achieve better performance requirements;

3. The organization and size are stable and the accuracy is guaranteed;

4. Improve and enhance processing performance.

Purpose of heat treatment

When the parts designed by the mechanical design engineer need to be heat treated, it is nothing more than the following requirements:

1. The purpose of eliminating the casting stress of the material is to obtain a more stable machining size and accuracy.

2. To improve the cutting performance of parts, the purpose is to have higher processing efficiency, better processing quality and lower processing costs during the processing of parts.

3. Improve the rigidity, hardness and wear resistance of parts.

The heat treatment requirements of most parts are designed around the above three aspects, so you only need to use the above four heat treatment methods according to your own requirements.