阅读说明：本技术 一种40Cr转向节锻后余热细化晶粒方法 (Method for refining grains by residual heat after forging of 40Cr steering knuckle ) 是由 祁斌 周细应 袁松 于 2019-10-23 设计创作，主要内容包括：本发明提供了一种40Cr转向节锻后余热细化晶粒方法。具体包括：加热所述40Cr转向节的胚料进行模锻,控制所述模锻的初始温度和终锻温度,得到40Cr转向节；将40Cr转向节放入网带炉中预冷；其后,将40Cr转向节投至冷却水中搅拌淬火,直至40Cr转向节的表面温度降低至50℃。采用本发明提供的40Cr转向节锻后余热细化晶粒方法,所得到的40Cr转向节综合性能更好,晶粒相对细化；并且在生产效率提高,降低成本的同时,进一步具有节能环保和提升产品质量的优势。(The invention provides a method for refining grains by using residual heat after forging of a 40Cr steering knuckle. The method specifically comprises the following steps: heating the blank of the 40Cr steering knuckle to perform die forging, and controlling the initial temperature and the final forging temperature of the die forging to obtain the 40Cr steering knuckle; placing the 40Cr steering knuckle into a mesh belt furnace for precooling; thereafter, the 40Cr knuckle was put into cooling water and stirred to be quenched until the surface temperature of the 40Cr knuckle was reduced to 50 ℃. By adopting the method for refining the crystal grains by the waste heat after the 40Cr steering knuckle is forged, the obtained 40Cr steering knuckle has better comprehensive performance and the crystal grains are relatively refined; and the production efficiency is improved, the cost is reduced, and the advantages of energy conservation, environmental protection and product quality improvement are further realized.)

1. The method for refining the grains by using the residual heat after forging the 40Cr steering knuckle is characterized by comprising the following steps of:

s1, heating the blank of the 40Cr steering knuckle to perform die forging, controlling the initial temperature of the die forging to be 1150 ℃, the finish forging temperature to be 900-950 ℃, and obtaining the 40Cr steering knuckle after the heating is finished;

s2, placing the 40Cr steering knuckle obtained in the step S1 into a mesh belt furnace to be precooled to 800-840 ℃ for 2-3 minutes;

and S3, putting the 40Cr steering knuckle obtained in the step S2 into cooling water, stirring and quenching until the surface temperature of the 40Cr steering knuckle is reduced to 50 ℃.

2. The post-forging residual heat grain-refining method of claim 1, wherein the temperature of the cooling water in step S3 is 20-40 ℃.

3. The post-forging residual heat grain-refining method of claim 3, wherein the temperature of the cooling water is 30 ℃.

Technical Field

The invention relates to the field of heat treatment of automobile parts, in particular to a method for refining grains by residual heat after forging of a 40Cr steering knuckle.

Background

With the rapid development of society, automobiles have become indispensable transportation means in people's lives. The steering knuckle, also known as a cleat, is one of the important parts in an automobile steering axle, and can enable an automobile to stably run and sensitively transmit the running direction.

The steering knuckle has the functions of transmitting and bearing the front load of the automobile, supporting and driving the front wheel to rotate around the main pin so as to steer the automobile. In the driving state of the vehicle, it is subjected to a variable impact load, and therefore, it is required to have a high strength. At present, for an automobile steering knuckle, two conventional methods for refining grains by waste heat after forging are available: the waste heat is utilized to directly quench and reheat to quench, and quenching medium is quenching oil or polymer medium. The former quenching treatment is generally liable to suffer from the following disadvantages: since the quenching temperature is high, the crystal grains are coarse and there is a possibility of deformation cracking. In addition, the quenching oil or polymer medium is relatively easy to cause environmental protection problem, and the waste medium is difficult to treat or has stable quality (the oil or polymer medium is easy to age and decompose at high temperature to cause unstable performance). The latter reheating and quenching treatment is liable to cause the following problems: the energy consumption is large, the production efficiency is low, and the economic benefit is low; the problems of environmental protection caused by large quenching medium, difficult treatment of waste medium or stable quality also exist. In addition, stress concentration is easy to occur at the transition position of the main pin and the flange due to the influence of structural stress and thermal stress in the production process of the steering knuckle of the small automobile, and the possibility of cracking is high. Therefore, it is important to control the heat treatment process in the quenching process.

Therefore, the invention provides a method for refining grains by residual heat after forging of the 40Cr steering knuckle, which can ensure that the austenite grain size of the 40Cr steering knuckle is relatively small and can further reduce the possibility of deformation and cracking of the steering knuckle. The method for refining the crystal grains by using the waste heat after forging can effectively refine the crystal grains, remarkably improve the performance stability and the production efficiency of the steering knuckle, save energy and effectively reduce the production cost.

Disclosure of Invention

In order to overcome the technical defects and solve the conventional problem, the invention provides a method for refining grains by using residual heat after forging of a 40Cr steering knuckle, which can ensure that the austenite grain size of the 40Cr steering knuckle is relatively small and can further reduce the possibility of deformation and cracking of the steering knuckle. The method for refining the crystal grains by using the waste heat after forging can effectively refine the crystal grains, remarkably improve the performance stability and the production efficiency of the steering knuckle, save energy, avoid environmental pollution and effectively reduce the production cost.

The invention provides a method for refining grains by using residual heat after forging of a 40Cr steering knuckle, which comprises the following steps:

s1, heating the blank of the 40Cr steering knuckle to perform die forging, controlling the initial temperature of the die forging to be 1150 ℃, the finish forging temperature to be 900-950 ℃, and obtaining the 40Cr steering knuckle after the heating is finished;

s2, placing the 40Cr steering knuckle obtained in the step S1 into a mesh belt furnace to be precooled to 800-840 ℃ for 2-3 minutes;

and S3, putting the 40Cr steering knuckle obtained in the step S2 into cooling water, stirring and quenching until the surface temperature of the 40Cr steering knuckle is reduced to 50 ℃.

Preferably, the temperature of the cooling water in step S3 is 20 to 40 ℃.

Preferably, the temperature of the cooling water is 30 ℃.

Compared with the prior art, the invention has the technical advantages that: by reducing the finish forging temperature of the 40Cr knuckle, the austenite grain size of the 40Cr knuckle is ensured to be relatively small. In addition, the invention further adopts water as a quenching medium, and reduces the possibility of deformation and cracking of the steering knuckle by controlling the precooling temperature and the precooling time. The method for refining the crystal grains by using the waste heat after forging can effectively refine the crystal grains, remarkably improve the performance stability and the production efficiency of the steering knuckle, save energy, avoid environmental pollution and effectively reduce the production cost.

Drawings

FIG. 1 is a schematic flow chart of the method for refining grains by waste heat after forging of a 40Cr steering knuckle.

Detailed Description

The advantages of the invention are further illustrated in the following description of specific embodiments in conjunction with the accompanying drawings.

Fig. 1 is a schematic flow chart of a post-forging residual heat grain refining method according to an embodiment of the present invention. The invention provides a method for refining grains by using residual heat after forging of a 40Cr steering knuckle. Specifically, the method for refining the grains by using the residual heat after forging comprises the following steps:

s1, heating the blank of the 40Cr steering knuckle, performing die forging on the blank of the steering knuckle through medium-frequency induction heating, wherein the die forging initial temperature is 1150 ℃, and the finish forging temperature of the 40Cr steering knuckle is controlled to be 900-950 ℃. The final forging temperature is controlled to be lower than the initial temperature, so that the deformation refined grains can be effectively applied to the sizes of austenite grains, and the quenching structure is relatively refined.

And S2, putting the 40Cr steering knuckle heated in the step S1 into a mesh belt furnace, and pre-cooling. The temperature of the mesh belt furnace is set to 800-840 ℃ to ensure that the heated 40Cr steering knuckle is cooled from 900-950 ℃ to 800-840 ℃. The pre-cooling time is typically 2-3 minutes. Through the pre-cooling operation in the mesh belt furnace, the surface and the core of the obtained 40Cr steering knuckle can have relatively uniform structure and performance, so that the possibility of deformation and cracking of the 40Cr steering knuckle is effectively reduced.

S3, putting the 40Cr steering knuckle obtained in the step S2 into cooling water, stirring and quenching, wherein the temperature of the cooling water is 20-40 ℃, and the preferred temperature is 30 ℃. The method for refining the grains by the residual heat after the 40Cr steering knuckle is forged, which is provided by the invention, adopts cooling water as a quenching medium to replace oil or a polymer medium, so that the problems of environmental pollution and unstable product quality are solved. When the surface temperature of the 40Cr steering knuckle is reduced to about 50 ℃ in cooling water, the process of refining grains by using waste heat after forging is completed, and the obtained 40Cr steering knuckle can effectively avoid deformation and cracking due to the slightly higher water outlet temperature, so that the quality of a product is ensured, and the reject ratio is reduced.

Example 1

3066 method for refining crystal grains by waste heat after forging of steering knuckle: 3066 heating the blank of the steering knuckle, die forging the blank in a medium frequency induction heating furnace, controlling the initial temperature of die forging at 1150 ℃ and the final temperature of die forging at 900-950 ℃. And after heating is finished, trimming the obtained steering knuckle, and then conveying the steering knuckle to a mesh belt furnace with the precooling temperature of 840 ℃ through a conveying device for directly precooling for 2-3min until the temperature of the steering knuckle is reduced to about 840 ℃. By adopting a precooling measure, the temperature of the steering knuckle is reduced, and the temperature difference between the surface and the core of the steering knuckle is reduced, so that the possibility of deformation and cracking of the steering knuckle is effectively reduced.

Then, the steering knuckle is further quickly put into a quenching water tank filled with cooling water of 30 ℃ by a conveying device and is continuously stirred, the water outlet temperature of the steering knuckle is controlled to be 50 ℃, and the deformation and the cracking of the steering knuckle are further avoided.

After the treatment by the method, the top of the 3066 knuckle was measured at 10mm from the surface and found to have a hardness of 47.6HRC and a grain size of about 6. The bottom of the knuckle was measured at a distance of 10mm from the surface to find that the hardness was 48.0HRC and the grain size was about 6 grade. And no micro-crack is found in the observation of the structure of the steering knuckle, thereby meeting the requirements of the structure and the performance of the steering knuckle.

Example 2

The method for refining the crystal grains by the waste heat after forging of the 1046B knuckle comprises the following steps: heating the blank of the 1046B knuckle, and die forging the blank by heating the blank in a medium-frequency induction heating furnace, wherein the initial temperature of die forging is controlled to be 1150 ℃, and the final forging temperature is controlled to be 900-950 ℃. And after heating is finished, trimming the obtained steering knuckle, and then conveying the steering knuckle to a mesh belt furnace with the precooling temperature of 840 ℃ through a conveying device for direct precooling for 3min until the temperature of the steering knuckle is reduced to about 840 ℃. By adopting a precooling measure, the temperature of the steering knuckle is reduced, and the temperature difference between the surface and the core of the steering knuckle is reduced, so that the possibility of deformation and cracking of the steering knuckle is effectively reduced.

Then, the steering knuckle is further quickly put into a quenching water tank filled with cooling water of 30 ℃ by a conveying device and is continuously stirred, the water outlet temperature of the steering knuckle is controlled to be 50 ℃, and the deformation and the cracking of the steering knuckle are further avoided.

After the treatment by the method, the hardness of the top of the obtained 1046B knuckle is detected to be 54.5HRC at a position 10mm away from the surface, and the grain size is 4-5 grade. The bottom of the knuckle was measured at 10mm from the surface and found to have a hardness of 52.0HRC and a grain size of 4-5 grade. And no micro-crack is found in the structure observation, thereby meeting the requirements of the structure and the performance of the steering knuckle.

Practice proves that: the method for refining the crystal grains by the waste heat after the 40Cr steering knuckle is forged can reduce pollution and cost and improve production efficiency. The obtained knuckle structure (main structure classification and grain size) and performance meet the quality related requirements of the knuckle.

It should be noted that the embodiments of the present invention have been described in terms of preferred embodiments, and not by way of limitation, and that those skilled in the art can make modifications and variations of the embodiments described above without departing from the spirit of the invention.