The method of thermal treatment of parts made of alloy steel

 

(57) Abstract:

Usage: the field of engineering, can be used for heat treatment of parts made of alloy steel and used in the design of the car. Essence: to improve strength characteristics of such parts used method of heat treatment, which consists in saturating the surface layer part of the carbon at the temperature 930-950oC followed by oil quenching and low temperature tempering, additionally held high holiday with subsequent hardening by high frequency currents and cooled to 5-10% aqueous solution of coolant with additives emulsifiers and subsequent low-temperature tempering. 3 Il., table 1.

The invention relates to mechanical engineering and can be used for heat treatment of parts made of alloy steel and used in the design of the car.

From the book Lactina Y. M. Leontieva C. P. "Materials. A textbook for engineering higher educational institutions" M: mechanical engineering, 1980, S. 230, there is a method of heat treatment of alloyed steel cementation, which consists in saturating the carbon surface layer with pocost core 32-45 HRC, and the depth of the hardened layer to the hardness 515 HV 0,9-1,4 mm

This heat treatment is widely used in many fields of engineering and, in particular, for cases of constant velocity joints (CV joints) front wheel drive cars VAZ. These enclosures hinges are made of alloyed steel type HG, HG, HG by cold extrusion. This method will get complex and high-precision parts, which do not require subsequent grinding operations.

However, this method of heat treatment has a significant disadvantage. For example, for buildings CV joint, consisting of hull, which is the hinge, and the tail current for torque transmission, the tail part, subjected to cementation, is an imperfect indicators of the strength and durability. A significant improvement of these indicators, especially the cyclic durability and the time of occurrence of the first crack when torsion is achieved while protecting the tail from cementation with the help of special pastes and the subsequent hardening tail currents of high frequency (HDTV). However, such pastes generally toxic, environmental and economic constraints do not apply in serala of alloy steels, as well as their cyclic durability and the formation of the first crack, and reducing the influence of the latter on cyclic durability.

This will improve the dimensions, lower weight, greater stability of the quality characteristics.

For this purpose, the method of heat treatment of parts made of alloy case hardening steel, which consists in the fact that the surface layer part is saturated with carbon at a temperature of 930 950oC followed by quenching in the quenching oil and low-temperature tempering, according to the invention additionally conduct high holiday items, heated by high frequency currents and quenching emulsifiers, and then perform low-temperature tempering.

The comparison of the proposed solutions with the level of technology on scientific, technical and patent documentation on the priority date has shown that the set of essential features of the claimed solution was not known, hence it corresponds to a condition of patentability "novelty."

Analysis of the known technical solutions in this field of technology showed that the proposed method has characteristics that are absent in the known technical solutions, and their use in the claimed owls who has an inventive step compared to the current level of technology.

The proposed method is industrially applicable, because it can be implemented in a known industrial equipment, therefore corresponds to the condition of patentability "industrial applicability".

Comparative testing of sample parts with the same geometric dimensions. Under No. 1 was presented to the sample without heat treatment. Under N 2 for a sample that has undergone only cementation. Under N 3 sample, the past only the annealing. Under N 4 specimen that has undergone the heat treatment by the present method, the main stages of which, reinforcing the sample are carburizing and annealing intermediate high holidays. The main indicator of the strength of the power parts, one of which is the tail part of the CV joint, is the yield stress, after which the item loses its geometrical dimensions. The details N 2, held only cementation, the yield strength increases by 56% details N 3, held only the annealing, the yield also increased by 56% In items # 4, the heat-treated by the present method, the yield strength increased by 134% This increase is more than the total increase of the yield strength of the samples, each of which was only one kind thermoabrasion characteristics are summarized in the table.

In addition, tests were carried out on a cyclic durability, in which the samples were loaded pulsating torque from 0 to 100 KGM KGM with a frequency of 1 Hz. They showed that the cyclic durability of parts, heat-treated by the present method, exceeds the requirements of the method (200 thousand cycles). For comparison, tests were carried out with samples pre-loaded torque, until the first crack. The initial crack in the samples with cementation was recorded at the moment 170 200 KGM, and the samples processed by the present method, at the moment more than 250 KGM. Then parts with cracks were tested for cyclic durability. The test results showed that the samples have undergone cementation, durability was 3 to 7 times lower than the base value of 200 thousand cycles, and samples processed by the present method, exceeded the base number of cycles.

In Fig. 1 shows the depth of the hardened layer details after saturation of the surface layer of a carbon (carburizing); Fig. 2 the depth of the hardened layer parts after quenching its high-frequency currents (TWh) of Fig. 3 the depth of the hardened layer of the workpiece after heat treatment of her by the claimed method, vkluchaetsia the hinge, and number 2 of his tail, which made slots used for transmission of torque.

The inventive method is carried out as follows.

Details of stainless steel, manufactured by cold extrusion method, put to saturate their surface carbon in the process furnace in which and conduct chemical-heat treatment at a temperature of 930-950oC.

Then perform their quenching tank with boarded-up oil and washing to remove oil from the surface of the parts. Next, produce a low-temperature tempering in a furnace with a temperature of 160-180oC. Heating to high temperature tempering (750-780oC) conduct currents of high frequency induction heating). Further details of the cooled air within the regulated time, for example for steel IN it is 2-3 minutes Then heated parts with high-frequency currents to the temperature 880-900oC and quenched them in 5-10% aqueous solution of coolant with additives emulsifiers. In particular, there is used an aqueous solution of coolant OSMANILA E2. Finally, perform low-temperature tempering in a furnace with a temperature of 160-180oC for 120-150 minutes

Thus, along with the complexity of the process by introducing additional operations, the claimed method of treatment has several advantages. First, increase the strength characteristics and increases the service life of critical components. The possibility of combining the operations of the high holidays and the subsequent quenching on the same equipment with the use of induction heating. Due to the high degree of mechanization and automation of the process achieved a high level of stability in quality, and therefore excluded the cases of marriage.

The method of thermal treatment of parts made of alloy steel including carburizing at 930 950oWith cooling, high-temperature tempering, quenching and low tempering, characterized in that the cooling after carburizing is carried out in the oil, then spend extra low vacation, heating under high-temperature tempering and quenching is performed by high-frequency currents, and cooling from the quenching temperature are within a 5 to 10% aqueous solution of coolant with additives emulsifiers.

 

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FIELD: rolling-mill machinery.

SUBSTANCE: the invention presents an installation for rolled metal cooling and is dealt with metal rolling, in particular with cooling of rolled metal. The installation for rolled metal cooling contains a body with an inlet branch-pipe and two rows of outlet branch-pipes displaced from each other by a half step. Value of a step of the outlet branch pipes in each row does not exceed four internal diameters of the branch-pipes. Across the body opposite to an entry of the inlet branch-pipe a dissector is installed. Along the body opposite to the outlet branch-pipes there are two entire central plates and two fragmentary lateral plates forming two longitudinal funnel-shaped cavities, turned by their narrow parts to each row of outlet branch-pipes. Fragmentariness of the lateral plates is created at the expense at least of one cutout in the base of each plate, at the longitudinal butts of which there are two perpendicularly fixed damping plates facing inside the funnel-shaped cavities. The invention allows to increase evenness, flexibility and efficiency of the rolling metal cooling process and ensures reliable operation of the installation.

EFFECT: the invention allows to increase evenness, flexibility and efficiency of the rolling metal cooling process and ensures reliable operation of the installation.

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