CN109750138B - Laser hardening method for steam inlet edge of large-thickness blade of steam turbine - Google Patents
Laser hardening method for steam inlet edge of large-thickness blade of steam turbine Download PDFInfo
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- CN109750138B CN109750138B CN201910023227.0A CN201910023227A CN109750138B CN 109750138 B CN109750138 B CN 109750138B CN 201910023227 A CN201910023227 A CN 201910023227A CN 109750138 B CN109750138 B CN 109750138B
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Abstract
The invention discloses a laser hardening method for a steam inlet edge of a large-thickness blade of a steam turbine, which comprises the following steps of: 1) pre-treatment, before laser hardening, removing oil and dust from the hardened area of the blade, brushing light absorbing agent and drying; 2) laser hardening, namely performing laser hardening on the back surface of the blade according to the required size, immediately performing laser hardening on the inner arc of the blade after the hardening of the back arc surface is finished, and continuously performing two hardening procedures; 3) cooling, namely standing and cooling the laser hardened blade; 4) tempering, namely performing tempering heat treatment on the laser-hardened blade; 5) polishing, namely polishing the hardened area of the tempered blade; 6) and (6) detecting the hardness. The steam inlet edge laser hardening method for the large-thickness blade of the steam turbine adopts a new process of back arc hardening and inner arc hardening, can perform laser hardening on the hardened areas of the inner and back arcs with larger width sizes, meets the hardening requirements of the blade, and is simple in process and easy to realize.
Description
Technical Field
The invention relates to a turbine blade processing technology, in particular to a laser hardening method for a steam inlet edge of a large-thickness turbine blade.
Background
The production process of the turbine blade meets a certain product which needs to be subjected to laser hardening on the air inlet edge of the blade made of X12 CrNiMoV. The size of the hardening zone is required as follows: referring to fig. 1 and 2, fig. 1 is a schematic view of a back arc hardening area of a conventional large-thickness blade for a steam turbine, fig. 2 is a schematic view of an inner arc hardening area of a conventional large-thickness blade for a steam turbine, where a in fig. 1 and 2 is a vertex of a blade inlet side, D1 is a back arc hardening width, D1 is an inner arc hardening width, the total length of the hardening area of the vertex of the blade inlet side is 200mm downward from the blade tip, a hardening area of 25mm from the inlet side in three gears of Z1, Z2 and Z3 which are 20mm, 90mm and 160mm from the blade tip is required to be a hardening area, and a non-hardening area of 33mm is required; the area of the inner arc, which is 4mm away from the air inlet edge, is a hardened area, and the area of the inner arc, which is 12mm away from the air inlet edge, is a non-hardened area (the hardness of the hardened area is more than or equal to 400HV, and the hardness of the non-hardened area is less than 350 HV). The method has strict requirements on the sizes of a hardened area and a non-hardened area of the back arc of the blade, and has the same requirements on the inner arc surface. For the blade, the conventional method is used for carrying out laser hardening on the back arc of the blade, and the hardened area size of the inner arc of the blade cannot meet the requirement. Especially for some vanes with thicker inlet edge hardened areas, the vanes with thicker inlet edges cannot meet the production requirements because the inner arc cannot be hardened or the hardening width is insufficient due to the faster self-cooling heat transfer.
Disclosure of Invention
The invention aims to provide a laser hardening method for the steam inlet edge of a large-thickness blade of a steam turbine, which aims to solve the problem that the hardening requirement cannot be met only by carrying out laser hardening on a back arc when the large-thickness blade of the steam turbine is hardened in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
a laser hardening method for the steam inlet edge of a large-thickness blade of a steam turbine comprises the following steps:
1) pre-treatment, before laser hardening, removing oil and dust in a hardened area of the blade, brushing and decorating a light absorbing agent, drying by blowing, and increasing the absorption of a laser irradiation area to laser energy;
2) laser hardening, namely performing laser hardening on the back surface of the blade according to the required size, monitoring hardening temperature in real time by using an infrared thermometer during laser hardening, and correspondingly adjusting the input laser power according to a temperature measurement result to ensure that the temperature of a light spot irradiation area is uniform and consistent in the whole process and does not have large fluctuation, performing laser hardening on the inner arc of the blade immediately after the hardening of the back arc surface is finished, wherein two hardening procedures are continuously performed and the middle part cannot be interrupted;
3) cooling, namely placing the laser hardened blade on a twisting frame for standing and cooling;
4) tempering, namely placing the laser hardened blade into a bench furnace for tempering heat treatment;
5) polishing, namely polishing the hardened area of the tempered blade to remove oxide skin;
6) and (4) hardness detection, namely performing hardening detection on the blade, and carrying out the next procedure after the blade is qualified.
Particularly, the speed of laser hardening the back surface of the blade in the step 2) is 80 mm/min-150 mm/min, and the hardening temperature is 1400 ℃ to 1800 ℃.
Particularly, the speed of laser hardening the inner arc of the blade in the step 2) is 90 mm/min-120 mm/min, and the hardening temperature is 1350 ℃ to 1700 ℃.
In particular, the specific process of the tempering heat treatment in the step 4) is as follows: the temperature is 250-290 ℃, the heat preservation time is 70-100 minutes, the heating rate is less than or equal to 70 ℃/h, the furnace is charged below 150 ℃, and the furnace is cooled to below 160 ℃, and the furnace is kept stand for air cooling or furnace cooling.
In particular, the detection method of step 6) is as follows: and cutting the hardened blade into a sample, preparing a metallographic sample, corroding the metallographic sample, and measuring the microhardness at a required position.
Compared with the prior art, the laser hardening method for the steam inlet edge of the large-thickness blade of the steam turbine has the advantages that a new process of back arc hardening and inner arc hardening is adopted, the hardening area with the inner and back arcs and the larger width size can be subjected to laser hardening, the hardening requirement of the blade is met, the process is simple, and the laser hardening method is easy to realize.
Drawings
FIG. 1 is a schematic view of a back arc hardened region of a prior art large thickness steam turbine blade;
FIG. 2 is a schematic illustration of an inner arc hardened region of a prior art large thickness steam turbine blade;
FIG. 3 is a schematic view of the Z1 gear position detection of the blade hardened by the laser hardening method for the steam inlet edge of the large-thickness blade of the steam turbine according to the invention;
FIG. 4 is a schematic view of the Z2 gear position detection of the blade hardened by the laser hardening method for the steam inlet edge of the large-thickness blade of the steam turbine according to the invention;
FIG. 5 is a schematic view of the Z3 gear position detection of the blade hardened by the laser hardening method for the steam inlet edge of the large-thickness blade of the steam turbine according to the invention;
FIG. 6 is a schematic view of the detection of the Z4 gear of the blade hardened by the laser hardening method for the steam inlet edge of the large-thickness blade of the steam turbine.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
Example one
In this embodiment, a laser hardening method for a steam inlet edge of a large-thickness blade of a steam turbine includes the following steps: 1) pre-treatment, before laser hardening, removing oil and dust in a hardened area of the blade, brushing and decorating a light absorbing agent, drying by blowing, and increasing the absorption of a laser irradiation area to laser energy; 2) laser hardening, namely performing laser hardening on the back surface of the blade according to the required size, wherein the back arc laser hardening speed is 80mm/min, the hardening temperature is 1400 ℃, an infrared thermometer is used for monitoring the hardening temperature in real time during laser hardening, and the input laser power is correspondingly adjusted according to the temperature measurement result, so that the temperature of a light spot irradiation area is uniform and consistent in the whole process, no large fluctuation exists, the inner arc of the blade is immediately subjected to laser hardening after the back arc surface is hardened, the inner arc laser hardening speed is 90mm/min, and the hardening temperature is 1350 ℃; the two hardening procedures are continuously carried out, and the middle part can not be interrupted; 3) cooling, namely placing the laser hardened blade on a twisting frame for standing and cooling; 4) tempering, namely placing the laser hardened blade into a bench furnace for tempering heat treatment, wherein the specific process of the tempering heat treatment comprises the following steps: the temperature is 250 ℃, the heat preservation time is 70 minutes, the heating rate is less than or equal to 70 ℃/h, the furnace is charged below 150 ℃, and the furnace can be stood for air cooling or furnace cooling when the furnace is cooled to below 160 ℃; 5) polishing, namely polishing the hardened area of the tempered blade to remove oxide skin; 6) and (4) hardness detection, namely performing hardening detection on the blade, and carrying out the next procedure after the blade is qualified.
Example two
In this embodiment, a laser hardening method for a steam inlet edge of a large-thickness blade of a steam turbine includes the following steps: 1) pre-treatment, before laser hardening, removing oil and dust in a hardened area of the blade, brushing and decorating a light absorbing agent, drying by blowing, and increasing the absorption of a laser irradiation area to laser energy; 2) laser hardening, namely performing laser hardening on the back surface of the blade according to the required size, wherein the back arc laser hardening speed is 115mm/min, the hardening temperature is 1600 ℃, an infrared thermometer is used for monitoring the hardening temperature in real time during laser hardening, and the input laser power is correspondingly adjusted according to the temperature measurement result, so that the temperature of a light spot irradiation area is uniform and consistent in the whole process, no large fluctuation exists, the inner arc of the blade is immediately subjected to laser hardening after the back arc surface is hardened, the inner arc laser hardening speed is 105mm/min, and the hardening temperature is 1525 ℃; the two hardening procedures are continuously carried out, and the middle part can not be interrupted; 3) cooling, namely placing the laser hardened blade on a twisting frame for standing and cooling; 4) tempering, namely placing the laser hardened blade into a bench furnace for tempering heat treatment, wherein the specific process of the tempering heat treatment comprises the following steps: the temperature is 270 ℃, the heat preservation time is 85 minutes, the heating rate is less than or equal to 70 ℃/h, the furnace is charged below 150 ℃, and the furnace can be stood for air cooling or furnace cooling when the furnace is cooled to below 160 ℃; 5) polishing, namely polishing the hardened area of the tempered blade to remove oxide skin; 6) and (4) hardness detection, namely performing hardening detection on the blade, and carrying out the next procedure after the blade is qualified.
EXAMPLE III
In this embodiment, a laser hardening method for a steam inlet edge of a large-thickness blade of a steam turbine includes the following steps: 1) pre-treatment, before laser hardening, removing oil and dust in a hardened area of the blade, brushing and decorating a light absorbing agent, drying by blowing, and increasing the absorption of a laser irradiation area to laser energy; 2) laser hardening, namely performing laser hardening on the back surface of the blade according to the required size, wherein the back arc laser hardening speed is 150mm/min, the hardening temperature is 1800 ℃, an infrared thermometer is used for monitoring the hardening temperature in real time during laser hardening, the input laser power is correspondingly adjusted according to the temperature measurement result, the temperature of a light spot irradiation area is uniform and consistent in the whole process, no large fluctuation exists, the inner arc of the blade is immediately subjected to laser hardening after the back arc surface is hardened, the inner arc laser hardening speed is 120mm/min, and the hardening temperature is 1700 ℃; the two hardening procedures are continuously carried out, and the middle part can not be interrupted; 3) cooling, namely placing the laser hardened blade on a twisting frame for standing and cooling; 4) tempering, namely placing the laser-hardened blade into a bench furnace for tempering heat treatment at 290 ℃, keeping the temperature for 100 minutes, heating up at a rate less than or equal to 70 ℃/h, charging at the temperature below 150 ℃, and standing for air cooling or furnace cooling when the temperature in the furnace is below 160 ℃; 5) polishing, namely polishing the hardened area of the tempered blade to remove oxide skin; 6) and (4) hardness detection, namely performing hardening detection on the blade, and carrying out the next procedure after the blade is qualified.
The hardness detection methods of the three embodiments are the same, the hardened blade is cut into a sample, a metallographic sample is prepared and corroded, and the microhardness is measured at a required position, as shown in fig. 3 to 6, the hardness result of each gear meets the hardening requirement.
The foregoing embodiments are merely illustrative of the principles and features of this invention, which is not limited to the above-described embodiments, but is capable of various modifications and changes without departing from the spirit and scope of the invention, which are intended to be within the scope of the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (5)
1. A laser hardening method for the steam inlet edge of a large-thickness blade of a steam turbine is characterized by comprising the following steps:
1) pre-treatment, before laser hardening, removing oil and dust in a hardened area of the blade, brushing and decorating a light absorbing agent, drying by blowing, and increasing the absorption of a laser irradiation area to laser energy;
2) laser hardening, namely performing laser hardening on the back surface of the blade according to the required size, monitoring hardening temperature in real time by using an infrared thermometer during laser hardening, and correspondingly adjusting the input laser power according to a temperature measurement result to ensure that the temperature of a light spot irradiation area is uniform and consistent in the whole process and does not have large fluctuation, performing laser hardening on the inner arc of the blade immediately after the hardening of the back arc surface is finished, wherein two hardening procedures are continuously performed and the middle part cannot be interrupted;
3) cooling, namely placing the laser hardened blade on a twisting frame for standing and cooling;
4) tempering, namely placing the laser hardened blade into a bench furnace for tempering heat treatment;
5) polishing, namely polishing the hardened area of the tempered blade to remove oxide skin;
6) and (4) hardness detection, namely performing hardening detection on the blade, and carrying out the next procedure after the blade is qualified.
2. The steam turbine large-thickness blade steam inlet edge laser hardening method according to claim 1, wherein the speed of laser hardening the back surface of the blade in the step 2) is 80 mm/min-150 mm/min, and the hardening temperature is 1400 ℃ to 1800 ℃.
3. The steam turbine large-thickness blade steam inlet edge laser hardening method according to claim 1, characterized in that the laser hardening speed of the blade inner arc in the step 2) is 90 mm/min-120 mm/min, and the hardening temperature is 1350 ℃ to 1700 ℃.
4. The steam turbine large-thickness blade steam inlet edge laser hardening method according to claim 1, characterized in that the tempering heat treatment in the step 4) comprises the following specific processes: the temperature is 250-290 ℃, the heat preservation time is 70-100 minutes, the heating rate is less than or equal to 70 ℃/h, the furnace is charged below 150 ℃, and the furnace is cooled to below 160 ℃, and the furnace is kept stand for air cooling or furnace cooling.
5. The steam turbine large-thickness blade steam inlet edge laser hardening method according to claim 1, characterized in that the detection method of the step 6) is as follows: and cutting the hardened blade into a sample, preparing a metallographic sample, corroding the metallographic sample, and measuring the microhardness at a required position.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910023227.0A CN109750138B (en) | 2019-01-10 | 2019-01-10 | Laser hardening method for steam inlet edge of large-thickness blade of steam turbine |
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| CN201910023227.0A CN109750138B (en) | 2019-01-10 | 2019-01-10 | Laser hardening method for steam inlet edge of large-thickness blade of steam turbine |
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| CN109750138B true CN109750138B (en) | 2021-02-09 |
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| CN1740350A (en) * | 2005-09-16 | 2006-03-01 | 浙江工业大学 | The laser reinforcing process of the intake side of turbine vane |
| CN101333584A (en) * | 2008-07-30 | 2008-12-31 | 无锡透平叶片有限公司 | Laser heat treatment vulcanized process for leading edge of blade |
| CN101871036A (en) * | 2009-04-23 | 2010-10-27 | 上海电气电站设备有限公司 | Laser processing technology for low-pressure last stage blade of steam turbine |
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