Heat treatment process for large-size 20CrMnMoB guide rail
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A large-scale, guide-rail technology, used in heat treatment furnaces, heat treatment equipment, manufacturing tools, etc., can solve the problems of uneven mechanical properties testing results of the whole section, excessive quenching and cooling of workpieces, and inability to finish machining due to workpiece deformation. Quenching effect and uniformity, small deformation of workpiece, effect of reducing deformation and cracking of workpiece
Inactive Publication Date: 2022-02-01
HENAN ZHONGYUAN SPECIAL STEEL EQUIP MFG CO LTD
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Problems solved by technology
[0002] At present, in the production of 20CrMnMoB guide rails, due to their large specifications and external dimensions of about 560*280*7800, according to the conventional production method, heat treatment is carried out in a box-type resistance furnace. After heat treatment, the workpiece is not only deformed seriously but also has uneven quenching and cooling. As a result, the workpiece cannot be finished due to serious deformation and the test results of the mechanical properties of the full section are uneven, and there are unqualified phenomena.
[0003] In order to solve the above problems, measures such as increasing the finishing allowance and turning on the largest quenching liquid stirring device during quenching are usually adopted, but the effect is minimal. Although increasing the finishing allowance solves the problem that the workpiece cannot be finished due to deformation after heat treatment, it causes The production cost is wasted, and the production cost will increase by at least 10%. The cooling water with high quenching and cooling force is used during production, which will cause deformation and cracking of the workpiece due to excessive quenching and cooling force. At the same time, although the maximum quenching and cooling water stirring device is turned on during quenching, the Since the workpiece cannot be turned over, and the stirring device is under the workpiece, resulting in uneven cooling on the upper and lower sides of the workpiece, a new heat treatment process is urgently needed to solve the technical problems in production
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Embodiment 1
[0022] Embodiment 1: A heat treatment process for a large-scale 20CrMnMoB guide rail.
[0026] The heat treatment process steps are as follows:
[0027] Step 1), process a central hole of φ170mm in the middle part of the sample at 200mm from the riser end of the workpiece, and use a φ165mm threading rod to pass through the central hole during heat treatment to hang the workpiece and place it in a 12-meter deep well furnace heating furnace;
[0028] Step 2), after the completion of step 1), perform quenching: when the workpiece enters the furnace, the furnace temperature is ≤450°C, and the temperature is raised to 550°C-570°C at a heating rate of ≤50°C / h-70°C / h, and the heat preservation is carried out 2h~4h, then heat up to 880℃~900℃ at a heating rate of ≤50℃ / h~70℃ / h, keep warm for 5...
Embodiment 2
[0036] Embodiment 2: A heat treatment process for a large-scale 20CrMnMoB guide rail.
[0040] The heat treatment process steps are as follows:
[0041] Step 1), process a central hole of φ170mm in the middle part of the sample at 200mm from the riser end of the workpiece, and use a φ165mm threading rod to pass through the central hole during heat treatment to hang the workpiece and place it in a 12-meter deep well furnace heating furnace;
[0042] Step 2), after the completion of step 1), perform quenching: when the workpiece enters the furnace, the furnace temperature is ≤450°C, and the temperature is raised to 550°C-570°C at a heating rate of ≤50°C / h-70°C / h, and the heat preservation is carried out 2h~4h, then heat up to 880℃~900℃ at a heating rate of ≤50℃ / h~70℃ / h, keep warm for 5h...
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Abstract
The invention relates to a heat treatment process for a large-sized 20CrMnMoB guide rail, which effectively solves the phenomena of deformation, cracking and non-uniform cooling after heat treatment of the large-sized 20CrMnMoB guide rail. A central hole is processed in the middle of a dead head end of a workpiece, and during heat treatment, a penetrating rod penetrates through the central hole to hang the workpiece in a pit furnace for suspending, so workpiece deformation in the heat treatment heating and quenching process is reduced; the integral uniform heating of the workpiece is ensured by adopting speed-limiting temperature rise and stepped heat preservation modes, the temperature difference inside and outside the workpiece is reduced, the internal thermal stress of the workpiece is reduced, and cracking or deformation of the workpiece is avoided; during quenching, a water-based liquid medium with the concentration of 9-15% is adopted for quenching and cooling, and the quenching effect and uniformity are guaranteed; and speed-limiting furnace cooling is adopted after tempering is finished, the internal stress of the workpiece can be effectively removed, finish machining deformation is avoided, the large-specification 20CrMnMoB guide rail produced through the method is small in workpiece deformation after heat treatment, the mechanical property of the total cross section is uniform and consistent, and the detection result is qualified.
Description
technical field [0001] The invention belongs to the technical field of heat treatment of metal materials, and in particular relates to a heat treatment process for a large-size 20CrMnMoB guide rail which effectively solves the deformation, cracking and uneven cooling of the large-size 20CrMnMoB guide rail after heat treatment. Background technique [0002] At present, in the production of 20CrMnMoB guide rails, due to their large specifications and external dimensions of about 560*280*7800, according to the conventional production method, heat treatment is carried out in a box-type resistance furnace. After heat treatment, the workpiece is not only deformed seriously but also has uneven quenching and cooling. As a result, the workpiece cannot be finished due to serious deformation and the test results of the mechanical properties of the full section are uneven, and there are unqualified phenomena. [0003] In order to solve the above problems, measures such as increasing the...
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Application Information
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