How tempering in heat treatment processes is formulated 10

It depends on the hardness and other mechanical properties of the material you are tempering.

Senior knife friends know that the knife production process must go through heat treatment, that is, annealing, normalizing, quenching, and tempering. And the most important and most used of these four fires is quenching and tempering.

Quenching is one method of making knife steel harder. First, the knife steel is heated to a certain temperature, which depends on the steel, and if you really have no experience, you can heat it to between 1050-1090°C, and then cool it quickly. The hardness of the knife steel is obtained through this process.

The principle is simple. During the austenite conversion process, the carbides in the knife steel are gradually dissolved, and the carbon and chromium brackets are suddenly dissolved and distributed in the steel matrix. When there is a sufficient amount of carbide dissolved in the knife steel, this state is maintained by rapidly cooling the steel, i.e. quenching.

During the quenching process, the structural structure of the steel is transformed from austenitic socks to martensite. As the microstructure transforms, the material will become harder and more wear-resistant, but also more brittle.

In order to reduce brittleness and improve toughness, it needs to be tempered. Usually the material is heated to 175-350 and tempered for about 2 hours to bridge the bridge, which can achieve a hardness of 53-63HRC and maintain a good balance between sharpness retention, wear resistance and toughness.

Tempering should be carried out within a reasonable time after quenching, preferably in about an hour, to reduce the brittleness caused by hardening. It is also crucial that the blade should be allowed to cool to room temperature before starting tempering, otherwise the martensitic transition will be interrupted and the hardening results will be weakened.

The specific temperature of tempering can be determined depending on the intended use of the tool. The higher the tempering temperature, the softer the material and the higher the toughness; The lower the tempering temperature, the harder and more brittle the material.

For example, a camping knife or survival knife can be tempered at a temperature of 350 to allow it to withstand rough handling without breaking; If the knife is expected to have good sharpness and edge retention, it can be tempered at 175°C for maximum hardness.

When the tempering temperature is below 175°C, it will achieve extremely high hardness, but it will cause the material to be very brittle. Similarly, tempering temperatures above 350°C should also be avoided, as this will lead to reduced brittleness and corrosion resistance. It is also important to note that if the tempered blade is exposed to a temperature higher than the tempering temperature, such as during grinding, the performance of the blade will be affected.

Proper quenching and tempering will result in a good balance between hardness, toughness and corrosion resistance of the finished insert.

Normalizing: The workpiece is heated to a suitable temperature and then cooled in the air, the effect of normalizing is similar to annealing, but the resulting structure is finer, and it is often used to improve the cutting performance of the material.

Annealing: The workpiece is heated to an appropriate temperature, different holding times are adopted according to the material and the size of the workpiece, and then slow cooling (the slowest cooling rate) is carried out, with the aim of making the internal structure of the metal reach or close to equilibrium, and obtain good process performance and service performance.

Quenching: After the workpiece is heated and insulated, it is quickly cooled in the quenching medium such as water, oil or other inorganic salts and organic aqueous solutions. After quenching, the steel becomes hard, but at the same time brittle.

Tempering: In order to reduce the brittleness of the steel, the quenched steel is kept warm for a long time at an appropriate temperature higher than room temperature and lower than 710, and then cooled.

Types of annealing.

1. Complete annealing and isothermal annealing.

Complete annealing, also known as crystalline annealing, is generally referred to as annealing, which is mainly used for casting, forgings and hot-rolled profiles of various carbon steels and alloy steels with sub-eutectic composition, and sometimes also used for welded structures. It is often used as a final heat treatment for some unimportant workpieces, or as a pre-heat treatment for some workpieces.

2. Spheroidization annealing.

Spheroidized annealing is mainly used for carbon steels and alloy tool steels (such as steel grades used in the manufacture of cutting tools, measuring tools, and molds). The main purpose is to reduce hardness, improve machinability and prepare for later quenching.

3. Stress relief annealing.

Stress relief annealing, also known as low-temperature annealing (or high-temperature tempering), is mainly used to eliminate the residual stress of castings, forgings, welded parts, hot-rolled parts, cold-drawn parts, etc. If these stresses are not relieved, they will cause deformation or cracks in the steel after a certain period of time, or during the subsequent cutting process.

Annealing The workpiece is heated to an appropriate temperature, with different holding times depending on the material and the size of the workpiece, followed by slow cooling (the slowest cooling rate), with the aim of making the internal structure of the metal reach or close to equilibrium, obtain good process properties and usability, or prepare the structure for further quenching.

Normalizing heats the workpiece to a suitable temperature and cools it in the air, the effect of normalizing is similar to annealing, but the resulting structure is finer, often used to improve the cutting performance of the material, and sometimes used for some parts with low requirements as the final heat treatment.

Quenching: After the workpiece is heated and insulated, it is quickly cooled in the quenching medium such as water, oil or other inorganic salts and organic aqueous solutions. After quenching, the steel becomes hard, but at the same time brittle.

In order to reduce the brittleness of the steel, the quenched steel is kept warm for a long time at an appropriate temperature above room temperature and below 710, and then cooled, this process is called tempering.

Annealing, normalizing, quenching and tempering are the "four fires" in the overall heat treatment, in which quenching and tempering are closely related, often used together, and one is indispensable.

Metal heat treatment is a process in which the metal workpiece is heated to a suitable temperature in a certain medium, and after being kept at this temperature for a certain period of time, it is cooled at different speeds. Metal heat treatment is one of the most important processes in material production, compared with other processing processes, heat treatment generally does not change the shape and overall chemical composition of the workpiece, but by changing the internal microstructure of the workpiece, or changing the chemical composition of the surface of the workpiece, to give or improve the performance of the workpiece. It is characterized by an improvement in the intrinsic quality of the workpiece, which is generally not observable to the naked eye.

The "four fires" in metal heat treatment refer to annealing, normalizing, quenching (solid solution) and tempering (aging).

There are four basic processes of metal heat treatment: annealing, normalizing, quenching and tempering, commonly known as the "four fires" of metal heat treatment.

What is the difference between quenching, tempering, normalizing, and annealing? Today is a long time to see.

What does normalizing, annealing, quenching, and tempering mean? Have you figured it all out?

There are four basic processes of metal heat treatment: annealing, normalizing, quenching and tempering, commonly known as the "four fires" of metal heat treatment.

First, the first fire of metal heat treatment - annealing:

1. Annealing is to heat the workpiece to an appropriate temperature, adopt different holding times according to the material and the size of the workpiece, and then carry out slow cooling, the purpose is to make the internal structure of the metal reach or close to equilibrium, obtain good process performance and use performance, or prepare for further quenching.

2. The purpose of annealing:

Improve or eliminate various structural defects and residual stresses caused by steel in the process of casting, forging, rolling and welding, and prevent deformation and cracking of workpieces.

Softening of chemical parts for machining.

Grain refinement and improvement of the structure to improve the mechanical properties of the workpiece.

Tissue preparation for final heat treatment (quenching, tempering).

Second, the second fire of metal heat treatment - normalizing:

1. Normalizing is to heat the workpiece to a suitable temperature and then cool it in the air, the effect of normalizing is similar to annealing, but the resulting structure is finer, often used to improve the cutting performance of the material, and sometimes used for some parts with low requirements as the final heat treatment.

2. The purpose of normalizing:

It can eliminate the overheated coarse grain structure and Wechsler structure of casting, forging and welding parts, and the strip structure in rolled materials; refinement of grains; It can also be used as a pre-heat treatment before quenching.

It can eliminate the reticulated secondary cementite and refine the pearlite, which not only improves the mechanical properties, but also facilitates the spheroidization annealing in the future.

Free cementite at grain boundaries can be eliminated to improve its deep-drawing properties.

3. The third fire of metal heat treatment - quenching:

1. Quenching is to heat and keep the workpiece warm, and then quickly cool it in water, oil or other inorganic salts, organic aqueous solutions and other quenching mediums. After quenching, the steel becomes hard, but at the same time brittle.

2. The purpose of quenching:

Improve the mechanical properties of finished metal or parts. For example, improve the hardness and wear resistance of tools and bearings, improve the elastic limit of springs, and improve the comprehensive mechanical properties of shaft parts.

Improve the material properties or chemical properties of certain special steels. For example, improve the corrosion resistance of stainless steel, increase the permanent magnetism of magnets, etc.

Fourth, the fourth fire of metal heat treatment - tempering:

1. In order to reduce the brittleness of the steel, the quenched steel is kept warm for a long time at an appropriate temperature higher than room temperature and lower than 710, and then cooled, which is called tempering.

2. The purpose of tempering:

Reduce internal stress and reduce brittleness, quenched parts have great stress and brittleness, if not tempered in time, it will often produce deformation and even cracking.

Adjust the mechanical properties of the workpiece, after the workpiece is quenched, the hardness is high and the brittleness is large, in order to meet the different performance requirements of various workpieces, it can be adjusted by tempering, hardness, strength, plasticity and toughness.

Stabilize the workpiece dimensions. Through tempering, the metallographic structure can be stabilized to ensure that it will not be deformed in the future use process.

Improve the cutting performance of certain alloy steels.

Anneal; Choose 500--550 degrees according to different materials.

Tempering; According to the material and use, it is divided into [low back 180--240, middle back 300--360, high back 580--660] normalizing.

Generally, 920-930 quenching is used.

According to different materials, 800-860 degrees are different.

The temperature of annealing, tempering, normalizing and quenching in heat treatment varies according to the structure and performance requirements of the material. In general, too high or too low a temperature will affect the physical properties of the material. Here are some typical heat treatment temperature ranges:

1.Annealing: generally between 500 -950, the annealing temperature of different metal materials is also different;

2.Tempering: The temperature is between 150 -700 °C, which usually needs to be adjusted according to the specific product thickness and hardness requirements;

3.Normalizing: The temperature is generally between 780 and 940, which can change the volume of detailed massive ferrite in the metal structure and the amount and shape of carbides;

4.Quenching: Different steels correspond to different quenching temperatures, generally between 820 -950.

It should be pointed out that different heat treatment methods and temperatures will also have different effects on the mechanical properties, corrosion resistance, and heat resistance of metal materials. Therefore, in practical application, it is necessary to choose the appropriate heat treatment method and temperature according to the characteristics of the material and the use environment to achieve the best effect.

Heat treatment is a common process in material processing, and annealing, tempering, normalizing, and quenching are the four basic processes. The exact temperature and time parameters of these processes are directly related to the type, shape, size, composition, etc. of the material to be treated, and need to be precisely designed and controlled on a case-by-case basis. Below are the approximate temperature ranges for each process:

1.Annealing: It is usually a heat treatment method in which the material is heated to a high temperature (400°C 900°C), stabilized for a certain period of time, and then cooled to room temperature.

The purpose of annealing is generally to soften the material, improve its plasticity, relieve stress, improve the uniformity of the structure, etc.

2.Tempering: It is a heat treatment method that heats the quenched and hardened material to a certain temperature range (below the critical temperature, usually 500 °C 700 °C), keeps it warm for a certain time, and then cools it at different temperatures.

The purpose of tempering is generally to improve the toughness of the material, reduce brittleness, and reduce residual stress.

3.Normalizing: It is a heating process that heats the material above the normal phase change temperature (850 °C 1000 °C), and combines it with a heat treatment process, mainly to heat the mild steel casting from high temperature to the normal phase transition zone, so as to achieve grain refinement, eliminate defects, improve material plasticity and other effects.

4.Quenching: It is a method of heating the material to an appropriate high temperature (800 °C to 1200 °C) and then rapidly cooling to a room temperature controlled between 0 and 60 °C.

The purpose of quenching is to cool the material quickly, so that its structure changes, enhances hardness, increases strength, and reduces toughness.

It should be noted that these temperature ranges are for reference only and do not represent the temperature range of all annealing, tempering, normalizing and quenching processes, and the specific situation also needs to be determined according to different materials, different process designs and actual working conditions.