Steel spring hardness 65g. The initial chemical composition of steel and the requirements for parts made from it. Optimal technological processes of material heat treatment

This alloy is a structural spring steel. This material has a high elasticity. In order to achieve such properties, the alloy is initially quenched, then subjected to medium temperature tempering.

As a rule, the following types of delivery are carried out from this material: long or shaped steel, calibrated and ground bars, silver pieces and tapes, thick-walled sheets, strips and wires, forged blanks, etc.

Products made of steel grade 65G are used in modern industry and engineering. An example of such details are:

• thrust washers and springs,
• gears and friction discs,
• springs and brake bands,
• clamping and feed collets,
• flanges and bearing housings,
• parts with high wear resistance,
• various elements that work without shock loads.

The exact chemical composition of steel grade 65G

Operational and specifications products made from this alloy, as well as its exact chemical composition, are regulated by the GOST 14959-79 standards. As part of 8 elements, the most common are: manganese, carbon and silicon. The secondary ones are:

• Chromium,
• Nickel,
• Copper,
• Sulfur and Phosphorus.

The exact percentage of all components is presented in the table below, and is also clearly shown in the diagram.

Properties of steel grade 65G

The specific gravity of this material is 7850 kg/m3. The hardness of the alloy according to Brinell reaches 10 -1 = 241 MPa. Critical points occur at the following temperature indicators:

• Ac1 = 721°
• Ac3(Acm) = 745°
• Ar3(Arcm) = 720°
• Ar1 = 670°
• Mn = 270°

The initial forging temperature is +1250°С, the final temperature varies from +760°С to +780°С. Workpieces with a cross section of up to 100 mm are cooled in air, cooling of products with a cross section of 101 mm to 300 mm is cooled in a trough.

Machinability is available in quenched and tempered condition with Brinell hardness of 240 units and tensile strength of 820 MPa.

Basically, products made from 65G steel are not used for welded structures. However, contact-spot welding is available for them without restrictions.

Parts made of this material may be prone to temper brittleness, provided that the composition contains about 1% manganese. In this case, the alloy is quite insensitive to the effects of flocs.

Polished rod and silver:, GOST 7419.0-78, GOST 7419.8-78. Sheet thick: . Tape:, GOST 1530-78, GOST 19039-73. Strip: , . Wire: . Forgings and forged blanks: .
Class: Structural spring-spring steel
Industrial use: springs, leaf springs, thrust washers, brake bands, friction discs, gears, flanges, bearing housings, clamping and feed collets and other parts that require increased wear resistance and parts that work without shock loads.

The use of steel 65G and heat treatment of products: spiral springs, sheet and spring washers are made of steel 65G and other spring steels. Spring steel is used to make springs. The hardness of the springs is within R c = 40-50, and spring washers R c = 40-48. Upon acceptance, the springs are checked for hardness and elasticity. The test method should, as far as possible, approximate the actual operating conditions of the springs (tension, compression or bending).

Springs made from heat-treated (patented) wire or tape of classes H, P and B undergo additional tempering at a temperature of 250-350 ° to relieve internal stresses that have arisen during their manufacture and to improve the elastic properties of the wire.

Spring release is best done in saltpeter baths for 5-10 minutes, depending on the cross section of the material. When tempering in oil or electric furnaces, special attention should be paid to the uniformity of heating. Vacation time in these furnaces is 20-40 minutes.

Springs made of annealed steel are quenched and tempered. In the case of making springs from wire with a diameter of more than 6 mm, before hardening, a high tempering is performed at a temperature of 670-720 ° to eliminate hardening resulting from cold winding. Hot-wound springs are normalized before hardening.

For heating for quenching, the springs are placed in chamber furnaces or salt baths heated to the required temperature. To avoid deformation, large springs are heated in a special device.

Small springs are loaded into the oven on a baking sheet. Exposure in the furnace should be the smallest - to prevent oxidation and decarburization. To reduce the residence time in the oven, small springs are placed on a preheated baking sheet. In the absence of a protective atmosphere in the furnace, the springs are packed in an insulating environment, or small amounts of charcoal are thrown into the furnace. Cool the springs in oil. It is not recommended to cool the springs in water to avoid cracking. If hardening in water is necessary, the exposure should be no more than 2-3 seconds. followed by cooling in oil.

Before release, the springs are cleaned of oil by washing in a soda solution or thoroughly rubbing in sawdust. Oil that is not removed from the springs flares up during vacation and changes the vacation conditions, which leads to uneven heating and low hardness. The tempering temperature is 300-420°. The annealing of the extreme turns is carried out in a lead bath.

Large springs are put on pipes before release to eliminate warping.

Attention should be paid to the surface of the material used for the manufacture of springs. Risks, hairlines and other defects lead to the formation of cracks, and the decarburized layer leads to a decrease in the elastic properties of the spring.

Quite often, anti-corrosion coatings used on a number of springs make them brittle due to hydrogen saturation of the metal during etching and during the coating process. This is especially noticeable on springs made of wire or tape of small cross section. This brittleness, called etching or hydrogen, is eliminated by heating the finished springs in oil, glycerin or an oven at a temperature of 150-180 ° for 1-2 hours.

However, during prolonged etching, the metal is saturated with hydrogen so strongly that the indicated temperature does not eliminate brittleness and the springs must be annealed. To avoid deep hydrogenation, springs made of thin wire or tape should not be pickled before coating, but should be sandblasted and heated after coating, as indicated above.