A heat treatment method for stress-lasting GH4169 bolts

Abstract

The invention discloses a heat treatment method for a stress-enduring GH4169 bolt, which is characterized in that it comprises the following steps: head hot upsetting, primary solution heat treatment, turning / grinding thread rolling blank diameter, thread rolling, secondary solution heat treatment, finishing, cold extrusion R, aging heat treatment, inspection / test. The invention improves the stress endurance performance of the bolt by adding a secondary solution heat treatment after the thread rolling process of the conventional stress-endurance bolt and adjusting its position with the cold extrusion R process, thereby changing the bolt heat treatment process method, significantly improving the stress endurance performance of the bolt, and ensuring that the stress endurance test of the fastener is qualified.

Description

Technical Field

[0001] The invention belongs to the technical field of heat treatment, in particular to a heat treatment method for a stress-lasting GH4169 bolt. Background Art

[0002] Aviation bolts made of GH4169 can be divided into stress-enduring type and fatigue type. Stress-enduring bolts are mainly used for bolts below 650℃ that require the best combination of tensile strength, endurance strength and anti-relaxation. The main processing process of conventional stress-enduring bolts is: head hot upsetting → solution heat treatment → finishing → cold extrusion R → rolling thread → aging heat treatment → inspection / testing. The product mechanical properties test items are hardness, room temperature tensile, high temperature tensile and stress fracture. At present, when manufacturing stress-enduring bolts according to conventional processing procedures, it is often encountered that the stress fracture test fails and the fracture occurs in less than 23h, resulting in the product being scrapped due to unqualified stress endurance. Summary of the invention

[0003] The object of the present invention is to overcome the above disadvantages and provide a heat treatment method for stress-enduring GH4169 bolts that can ensure that the fastener passes the stress-endurance test.

[0004] The purpose of the present invention and the solution of its main technical problems are achieved by adopting the following technical solutions:

[0005] A heat treatment method for a stress-persistent GH4169 bolt of the present invention is characterized in that it comprises the following steps:

[0006] 1) Hot upsetting of the head;

[0007] Hot upsetting of bolt heads is performed according to the product design head shape;

[0008] 2) One solution heat treatment;

[0009] Select solution heat treatment equipment according to needs, set heat treatment parameters and then air cool or cool faster;

[0010] 3) Turning / grinding the diameter of the thread rolling blank;

[0011] Turn / grind the diameter of the thread rolling blank and roll the thread;

[0012] 4) Secondary solution heat treatment;

[0013] Perform secondary solution heat treatment, set heat treatment parameters and then air cool or cool faster;

[0014] 5) Finishing;

[0015] Carry out bolt finishing and cold extrusion R process;

[0016] 6) Aging heat treatment;

[0017] Select aging heat treatment equipment according to needs, set heat treatment parameters, and then air cool;

[0018] 7) Inspection / testing;

[0019] Carry out bolt size inspection and performance testing.

[0020] In the step 2), the heat treatment parameters are set to 960° C.-980° C. for 1 hour.

[0021] In the step 4), the heat treatment parameters are set to 970° C.-990° C. for 1 hour.

[0022] In the step 6), the heat treatment parameters are set as keeping the temperature at 710° C.-730° C. for 8 hours, cooling to 610° C.-630° C. at a rate of 40-60° C. / h, and keeping the temperature for 8 hours.

[0023] Compared with the prior art, the present invention has obvious beneficial effects; from the above technical scheme, it can be seen that: after the conventional stress-lasting bolt thread rolling process, a secondary solid solution heat treatment is added and its position with the cold extrusion R process is adjusted. The main processing process of the optimized bolt is: head hot upsetting → primary solid solution heat treatment → turning / grinding rolling thread blank diameter → thread rolling → secondary solid solution heat treatment → finishing → cold extrusion R → aging heat treatment → inspection / testing. The parameters of the primary solid solution heat treatment are: keep warm at 960℃-980℃ for 1h and then air cool or cool faster; the parameters of the secondary solid solution heat treatment are: keep warm at 970℃-990℃ for 1h and then air cool or cool faster; the parameters of the aging heat treatment are: keep warm at 710℃-730℃ for 8h, cool to 610℃-630℃ at a rate of 40-60℃ / h, keep warm for 8h, and then air cool. By adding a secondary solution heat treatment after the conventional stress-endurance bolt thread rolling process and adjusting its position with the cold extrusion R process, the bolt heat treatment process method is changed to improve the stress endurance performance of the bolt, significantly improve the stress endurance performance of the bolt, and ensure that the fastener stress endurance test is qualified. DETAILED DESCRIPTION

[0024] The specific implementation methods, structures, features and functions of the present invention are described in detail below in conjunction with preferred embodiments.

[0025] The purpose of the present invention and the solution of its main technical problems are achieved by adopting the following technical solutions:

[0026] Example 1

[0027] The invention discloses a furnace temperature control method for heat treatment process test of small aviation parts, which is characterized by comprising the following steps: firstly, hot upsetting the bolt head according to the product design head shape, then performing a solid solution heat treatment, the heat treatment system is heat preservation at 960°C for 1 hour, air cooling or faster cooling, and then performing a secondary solid solution heat treatment after thread rolling, the heat treatment system is heat preservation at 990°C for 1 hour and faster cooling, and then performing finishing, cold extrusion R and aging heat treatment, the heat treatment system is heat preservation at 710°C for 8 hours, cooling to 610°C at a rate of 40°C / h, heat preservation for 8 hours, and then air cooling, and finally performing size inspection and performance test of the bolt.

[0028] Example 2

[0029] The invention discloses a furnace temperature control method for heat treatment process test of small aviation parts, which is characterized by comprising the following steps: firstly, hot upsetting the bolt head according to the product design head shape, then performing a solid solution heat treatment, the heat treatment system is heat preservation at 970°C for 1 hour, air cooling or faster cooling, and then performing a secondary solid solution heat treatment after thread rolling, the heat treatment system is heat preservation at 980°C for 1 hour and air cooling, and then performing finishing, cold extrusion R and aging heat treatment, the heat treatment system is heat preservation at 720°C for 8 hours, cooling to 620°C at a rate of 50°C / h, heat preservation for 8 hours, and then air cooling, and finally performing size inspection and performance test of the bolt.

[0030] Example 3

[0031] The invention discloses a furnace temperature control method for heat treatment process test of small aviation parts, which is characterized by comprising the following steps: firstly, hot upsetting the bolt head according to the product design head shape, then performing a solid solution heat treatment, the heat treatment system is heat preservation at 990°C for 1 hour, air cooling or faster cooling, and then performing a secondary solid solution heat treatment after thread rolling, the heat treatment system is heat preservation at 990°C for 1 hour and faster cooling, and then performing finishing, cold extrusion R and aging heat treatment, the heat treatment system is heat preservation at 730°C for 8 hours, cooling to 630°C at a rate of 60°C / h, heat preservation for 8 hours, and then air cooling, and finally performing size inspection and performance test of the bolt.

[0032] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A heat treatment method for stress-lasting GH4169 bolts, characterized in that: The following steps are involved: 1) Head hot upsetting: Hot upsetting of bolt heads is performed according to the product design head shape; 2) Primary solution heat treatment: Select solution heat treatment equipment according to demand, set heat treatment parameters and then air cool; 3) Turning / grinding thread rolling blank diameter: Turning / grinding the diameter of the thread rolling blank and rolling the thread; 4) Secondary solution heat treatment: Perform secondary solution heat treatment, set heat treatment parameters and then air cool; 5) Finishing: Carry out bolt finishing and cold extrusion R process; 6) Aging heat treatment: Select aging heat treatment equipment according to needs, set heat treatment parameters, and then air cool; 7) Inspection / test: Carry out bolt size inspection and performance testing.

2. A furnace temperature control method for heat treatment process test of small aviation parts as claimed in claim 1, characterized in that; In the step 2), the heat treatment parameters are set to 960° C.-980° C. for 1 hour.

3. A furnace temperature control method for heat treatment process test of small aviation parts as claimed in claim 1, characterized in that; In the step 4), the heat treatment parameters are set to 970° C.-990° C. for 1 hour.

4. A furnace temperature control method for heat treatment process test of small aviation parts as claimed in claim 1, characterized in that; In the step 6), the heat treatment parameters are set as keeping the temperature at 710° C.-730° C. for 8 hours, cooling to 610° C.-630° C. at a rate of 40-60° C. / h, and keeping the temperature for 8 hours.