CN110669906A - Heat treatment method for mechanical detection of high-strength spring steel - Google Patents

Abstract

The invention discloses a heat treatment method for mechanical detection of high-strength spring steel, which comprises a spring steel heat treatment system, an induction heater, an infrared thermometer, a temperature controller, a quenching tank, a sample clamp and other indispensable electrical elements, wherein the spring steel heat treatment system has induction heating, temperature measuring, temperature controlling and cooling functions; the infrared thermometer measures the temperature of the sample heated by the induction heater, and the heating temperature and the heat preservation time are controlled by the temperature controller. The method has the advantages of short heating time, fine grain size of the sample, higher mechanical property, accurate temperature measurement as the sample temperature, reduction of the production inspection time of the spring steel and improvement of the production efficiency.

Description

Heat treatment method for mechanical detection of high-strength spring steel

Technical Field

The invention relates to the technical field of spring steel heat treatment, in particular to a heat treatment method for mechanical detection of high-strength spring steel.

Background

Spring steel refers to steel that is used specifically for the manufacture of springs and elastic elements. The elasticity of steel depends on its ability to deform elastically, i.e. within a specified range, to withstand a certain load without permanent deformation after the load is removed. The spring steel should have excellent overall properties such as mechanical properties, anti-creep properties, fatigue properties, hardenability, etc.

In order to verify the qualification of the high-strength spring steel, the mechanical property test after heat treatment is required when the high-strength spring steel is delivered from a factory, a proportion sample with the diameter of 10mm is generally adopted, a sample blank with a certain machining allowance is reserved, and the longitudinal mechanical property of the steel is measured after the heat treatment and the machining allowance removal. Because the sample is small, the existing heat treatment method is to use a box-type heating furnace for quenching at the temperature of more than 800 ℃, oil quenching and tempering at the temperature of more than 400 ℃. The method has the defects that the display temperature of the box type heating furnace is the furnace temperature, the heating temperature of the sample is not the same, the temperature fluctuation is large, and the error of the detected mechanical property distance truth value is large. Meanwhile, in order to enable the sample to be soaked, the heat preservation time is long, so that the austenite grain size of the sample is large, the toughness of the sample is reduced, and the mechanical property test result of the high-strength spring steel is often not good. In addition, the total time of heat treatment is usually more than two hours for sufficient heat preservation, so that the time cost is increased, and the production efficiency is reduced.

Method of the invention

The invention aims to provide a heat treatment method for mechanical detection of high-strength spring steel, which can improve the mechanical property index of heat treatment of the spring steel, reduce the production inspection time and improve the production efficiency.

In order to achieve the purpose, the technical scheme of the invention is as follows: a heat treatment method for mechanical detection of high-strength spring steel is characterized by comprising a spring steel heat treatment system, an induction heater, an infrared thermometer, a temperature controller, a quenching tank, a sample clamp and other indispensable electrical elements, wherein the spring steel heat treatment system has induction heating, temperature measuring, temperature controlling and cooling functions; the infrared thermometer measures the temperature of the sample heated by the induction heater, and the heating temperature and the heat preservation time are controlled by the temperature controller.

A heat treatment method for mechanical detection of high-strength spring steel comprises the following steps:

(1) placing a sample in the induction coil, starting a power supply, and aligning an infrared thermometer to the central point of the cross section of the sample;

(2) setting a specified quenching temperature and heat preservation time on a temperature controller;

(3) starting, and automatically stopping the induction coil after the heating temperature and the heat preservation time set in the step (2) are finished;

(4) taking out the sample by using sample pliers, and putting the sample into a quenching tank for quenching;

(5) after drying the sample, continuously placing the sample into an induction coil, repeating the step (2), starting a temperature controller, setting a designated tempering temperature and heat preservation time, and repeating the step (3);

(6) and taking out the sample, cooling the sample to room temperature, and measuring the mechanical property of the sample on a tensile testing machine.

Compared with the prior art, the invention has the advantages that: the heating time is short, the grain size of the sample is fine, the mechanical property is higher, the determination temperature is the sample temperature, the temperature determination is accurate, the spring steel production inspection time is reduced, and the production efficiency is improved.

The high-strength spring steel mechanical detection heat treatment method provided by the invention is used for heating through the induction heater, and controlling the heating temperature and the heat preservation time through the infrared thermometer and the temperature controller, so that the heat treatment of the quenching and tempering process of the spring steel sample can be performed, and the mechanical property value after the heat treatment can be accurately obtained.

Drawings

FIG. 1 shows a structure after heat treatment by the heat treatment process of the present invention.

Detailed Description

The following examples are intended to illustrate the invention, but the scope of protection of the invention is not limited to the following examples.

The specific embodiment of the invention is as follows:

TABLE 155 melting chemical composition in weight percent (wt%) of SiCrV spring Steel

Number plate	C	Si	Mn	P	S	Cr	V
								55SiCrV	0.56	1.40	0.72	0.009	0.001	0.73	0.20

The heat treatment system components comprise a 120KW induction heater, an infrared thermometer, a liquid crystal display temperature controller, a quenching tank, quenching oil, sample clamps, a cooling system, other indispensable electrical elements, water pipes and the like. By adopting the spring steel heat treatment device, aiming at the steel 55SiCrV (shown in table 1) for the automobile suspension spring with the diameter of 18mm, the heat treatment process steps and parameters are as follows:

(1) processing a sample into a proportional sample (examples 1 and 2) with the diameter of 10mm and the total length of 110mm, putting the proportional sample into a quartz tube of an induction coil (the length of the quartz tube is multiplied by the diameter of 18mm multiplied by 20mm), turning on a power supply, and aligning an infrared thermometer to the central point of the cross section of the sample;

(2) setting the quenching temperature to 860 ℃ on a temperature controller control panel, and keeping the temperature for 4 s;

(3) starting the induction heater, and automatically stopping the work of the induction coil after the temperature and the heat preservation time are set in the step (2);

(4) immediately taking out the sample by using the sample clamp, putting the sample into a quenching tank for quenching, and airing the sample after quenching;

(5) continuously placing the sample into an induction coil, setting the tempering temperature to be 410 ℃, and keeping the temperature for 8 s;

(6) and (5) air cooling the sample, and detecting the mechanical property on a tensile testing machine after cooling.

Meanwhile, the samples cut by the same hook number are subjected to heat treatment in a box-type heating furnace (comparative example), and the heat treatment process comprises the following steps: quenching at 860 ℃, preserving heat for 30min, oil quenching, tempering at 410 ℃, preserving heat for 90min, and air cooling. The heat-treated sample was subjected to a tensile test. The results are shown in Table 2.

In addition, the austenite grain size and the quenched and tempered structure of the sample were measured by the above two heat treatment methods, respectively, and the results are shown in table 2.

TABLE 2 post heat treatment Performance index, texture, Austenite grain size

As can be seen from Table 2, the heat treatment mechanical property of the spring steel is detected by the heat treatment method, the mechanical property is excellent, the spring steel has obvious fine crystal effect, the structure is tempered troostite, and meanwhile, the method is convenient to operate, saves time and obviously shortens the inspection period.

The above description is only for specific exemplary description of the present invention, and it should be noted that the specific implementation of the present invention is not limited by the above manner, and it is within the protection scope of the present invention as long as various insubstantial modifications are made by using the technical idea and technical solution of the present invention, or the technical idea and technical solution of the present invention are directly applied to other occasions without modifications.

Claims (2)

1. A heat treatment method for mechanical detection of high-strength spring steel is characterized by comprising a spring steel heat treatment system, an induction heater, an infrared thermometer, a temperature controller, a quenching tank, a sample clamp and other indispensable electrical elements, wherein the spring steel heat treatment system has induction heating, temperature measuring, temperature controlling and cooling functions; the infrared thermometer measures the temperature of the sample heated by the induction heater, and the heating temperature and the heat preservation time are controlled by the temperature controller.

2. The heat treatment method for mechanical detection of the high-strength spring steel as claimed in claim 1, wherein the method comprises the following steps:

(1) placing a sample in the induction coil, starting a power supply, and aligning an infrared thermometer to the central point of the cross section of the sample;

(2) setting a specified quenching temperature and heat preservation time on a temperature controller;

(3) starting, and automatically stopping the induction coil after the heating temperature and the heat preservation time set in the step (2) are finished;

(4) taking out the sample by using sample pliers, and putting the sample into a quenching tank for quenching;

(5) after drying the sample, continuously placing the sample into an induction coil, repeating the step (2), starting a temperature controller, setting a designated tempering temperature and heat preservation time, and repeating the step (3);

(6) and taking out the sample, cooling the sample to room temperature, and measuring the mechanical property of the sample on a tensile testing machine.

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