Hardening treatment process for hard alloy valve rod brazing steel link handle

Abstract

The invention discloses a hardening treatment process for a hard alloy valve rod brazed steel link handle, which comprises the following steps of: pretreating a steel billet, preserving heat at 1040-1060 DEG C for 1 hour, and cooling with water; surface treatment: processing a steel billet to remove an oxide layer, and grinding the alloy valve rod to a preset size; cleaning treatment: cleaning the part and the solder by using an organic solvent or ultrasonic waves to remove oil stains; assembling and combining: combining according to a preset relation to ensure the solder position; high-frequency induction brazing: heating at 880-910 DEG C, preserving heat, and naturally cooling; and carrying out precipitation hardening treatment, namely keeping the temperature at 450-460 DEG C for 2 hours, and then carrying out furnace cooling or air cooling. According to the method, the hardness of the steel link handle reaches HRC36-41, the use requirement is met, welding flux loss and high-temperature failure are avoided, welding reliability is guaranteed, defects are avoided, and the joint quality is good.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat treatment, in particular to a hard alloy valve rod brazing steel connecting handle hardening process. BACKGROUND

[0002] In the prior art, there is a whole hard alloy. However, the whole hard alloy is easy to be damaged when it is impacted due to its fragile material characteristics during use;

[0003] When the hard alloy valve rod brazing steel connecting handle is connected, the existing connection method is brazing, but the steel connecting handle requires a hardness of HRC36-41, and after high-temperature brazing, the hardness of the steel part will decrease, which cannot meet the technical requirements, which has a negative impact on the quality and use of the product;

[0004] Therefore, we propose a hard alloy valve rod brazing steel connecting handle hardening process. SUMMARY

[0005] The purpose of the present application is to provide a hard alloy valve rod brazing steel connecting handle hardening process, which solves the problems raised in the background art.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a hard alloy valve rod brazing steel connecting handle hardening process, comprising the following process steps:

[0007] Step one: steel billet pretreatment: place the steel billet in a muffle furnace, heat at a temperature of 1040-1060℃ for 1 hour, and then cool to room temperature by water cooling;

[0008] Step two: surface treatment: mechanically process the cooled steel billet to remove the surface oxide layer to expose the fresh metal surface; at the same time, grind the hard alloy valve rod to remove the sintered surface to the preset size and surface roughness;

[0009] Step three: cleaning treatment: use organic solvent cleaning or ultrasonic cleaning to clean the steel connecting handle, hard alloy valve rod and welding material, and remove surface dirt and impurities;

[0010] Step four: assembly: assemble the cleaned steel connecting handle, hard alloy valve rod and welding material according to the preset assembly relationship to ensure that the welding material is located at the welding position;

[0011] Step five: high-frequency induction brazing: heat the assembled assembly by high-frequency induction to a temperature of 880-910℃ for brazing, stop heating after a preset time, and cool naturally;

[0012] Step 6: Precipitation hardening treatment: Place the brazed components in a muffle furnace and hold them at 450-460℃ for 2 hours to complete precipitation hardening. After that, cool them with the furnace or air cool them to room temperature.

[0013] In a preferred embodiment of the present invention, the steel connecting handle is made of 17-4PH precipitation-type stainless steel.

[0014] In a preferred embodiment of the present invention, in step one, the heating rate of the muffle furnace is 5-10℃ / min until it reaches 1040-1060℃.

[0015] In a preferred embodiment of the present invention, the solder is a silver-copper three-layer structure solder with the composition of Ag20+BCu58+Ag20, and the soldering temperature of the solder is greater than 800°C.

[0016] In a preferred embodiment of the present invention, in step three, the organic solvent is alcohol, acetone or gasoline.

[0017] In a preferred embodiment of the present invention, in step five, the heat preservation time for high-frequency induction brazing is 1-3 minutes.

[0018] In a preferred embodiment of the present invention, in step six, the heating rate of the muffle furnace is 3-8°C / min until it reaches 450-460°C.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] This invention achieves the required hardness of the steel connecting shank to HRC36-41 through brazing, meeting the hardness requirements during use. During heat treatment, it prevents solder loss and high-temperature failure, ensuring welding reliability. Furthermore, the welding is defect-free, and the weld joint quality is excellent, meeting the weld joint quality requirements. Attached Figure Description

[0021] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0022] Figure 1 This is a flow chart of the hardening process for brazing a steel connecting handle to a cemented carbide valve stem according to the present invention. Detailed Implementation

[0023] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0024] like Figure 1As shown, a hardening process for brazing a steel connecting shank to a cemented carbide valve stem is implemented as follows:

[0025] Raw material and equipment preparation

[0026] Steel connecting handle: 17-4PH precipitation type stainless steel billet is selected, and its size is determined according to the preset product specifications.

[0027] Carbide valve stem: Made of carbide material that meets industry standards, with initial dimensions reserved for grinding.

[0028] Solder: A silver-copper three-layer structure solder is selected, consisting of Ag20+BCu58+Ag20 (by weight). Its brazing temperature must be greater than 800℃ to ensure matching with the process temperature.

[0029] Cleaning reagents: Prepare alcohol (or acetone, gasoline) as an organic solvent for cleaning.

[0030] Equipment: muffle furnace (with temperature control and heating rate adjustment function), high frequency induction brazing equipment, machining equipment (such as lathes and grinding machines), ultrasonic cleaning machine.

[0031] Specific process steps implementation

[0032] Step 1: Billet Pretreatment

[0033] Place the 17-4PH stainless steel billet into a muffle furnace, set the heating rate to 5-10℃ / min, and gradually heat it to 1040-1060℃ (for example, select 1050℃).

[0034] After reaching the target temperature, maintain the temperature for 1 hour to ensure uniform internal temperature of the billet.

[0035] After the heat preservation is completed, the steel billet is quickly removed and cooled to room temperature by water cooling to complete the pretreatment.

[0036] Step 2: Surface Treatment

[0037] After cooling, the steel billet is machined (e.g., turned, ground) to remove the surface oxide layer until a fresh metal surface is exposed, ensuring the bonding strength of subsequent welding.

[0038] Meanwhile, the carbide valve stem is ground according to preset dimensions (such as diameter and length) and surface roughness (such as Ra0.8μm) to ensure the assembly accuracy with the steel connecting handle.

[0039] Step 3: Cleaning

[0040] The machined steel connecting handle, carbide valve stem, and silver-copper triple-layer solder were cleaned separately:

[0041] If using organic solvents for cleaning, you can soak and wipe with alcohol to remove surface oil, dust and other impurities;

[0042] If ultrasonic cleaning is used, place the workpiece in the cleaning tank, add alcohol as the cleaning medium, and ultrasonically clean for 10-15 minutes to enhance the cleaning effect.

[0043] After cleaning, allow the workpiece to air dry to avoid secondary contamination.

[0044] Step 4: Assembly

[0045] Align the two parts according to the preset assembly relationship (such as the docking position of the steel connecting handle and the carbide valve stem), place three layers of silver and copper solder on the part to be welded (such as the joint), and ensure that the solder completely covers the welding area and the workpiece is firmly fixed to prevent displacement during heating.

[0046] Step 5: High-frequency induction brazing

[0047] Place the assembled components into the induction coil of the high-frequency induction brazing equipment, adjust the equipment parameters, and start heating.

[0048] Control the heating rate to rapidly heat the workpiece to 880-910℃;

[0049] After reaching the target temperature, hold for 1-3 minutes (adjust according to the welding area, such as 1 minute for small workpieces) to ensure that the solder melts fully and wets the welding interface.

[0050] After the heat preservation is completed, stop heating, remove the assembly, and allow it to cool naturally to room temperature to complete the brazing.

[0051] Step Six: Precipitation Hardening Treatment

[0052] Place the brazed components into a muffle furnace, set the heating rate to 3-8℃ / min, and heat to 450-460℃.

[0053] After reaching the target temperature, hold for 2 hours to allow the 17-4PH stainless steel to precipitate a strengthening phase, thereby increasing its hardness.

[0054] After the heat preservation is completed, you can choose to cool with the furnace (slowly cool down to reduce internal stress) or air cool (let it cool down naturally) to room temperature to complete the entire hardening process.

[0055] Finally, after the above-mentioned process, the finished product is tested. The hardness of the steel connecting handle can reach HRC36-41, which meets the technical requirements. The welded joint is free of defects such as pores and cracks. The tensile test shows that the welding strength meets the design standard.

[0056] In summary, the brazing process ensures that the hardness of the steel connecting shank reaches the required range of HRC36-41, meeting the hardness requirements for use. During heat treatment, it prevents solder loss and high-temperature failure, guaranteeing the reliability of the weld. Furthermore, the weld is defect-free, and the weld joint is of good quality, meeting the weld joint quality requirements.

[0057] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0058] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A hardening process for brazing a steel connecting handle to a cemented carbide valve stem, characterized in that: The process includes the following steps: Step 1: Billet pretreatment: Place the billet in a muffle furnace and hold it at 1040-1060℃ for 1 hour, then cool it to room temperature by water cooling. Step 2: Surface treatment: The cooled steel billet is machined to remove the surface oxide layer until the fresh metal surface is exposed; at the same time, the carbide valve stem is ground to remove its sintered surface to the preset size and surface roughness. Step 3: Cleaning: Use organic solvents or ultrasonic cleaning to clean the steel connecting handle, carbide valve stem and solder used for welding, and remove surface oil and impurities; Step 4: Assembly: Assemble the cleaned steel connecting handle, carbide valve stem and solder according to the preset assembly relationship, ensuring that the solder is located at the part to be welded; Step 5: High-frequency induction brazing: The assembled components are subjected to high-frequency induction heating, and brazing is performed at 880-910℃. After holding at the temperature for a preset time, heating is stopped, and the components are allowed to cool naturally. Step 6: Precipitation hardening treatment: Place the brazed components in a muffle furnace and hold them at 450-460℃ for 2 hours to complete precipitation hardening. After that, cool them with the furnace or air cool them to room temperature.

2. The hardening treatment process for brazed steel connecting handles of a cemented carbide valve stem according to claim 1, characterized in that: The steel connecting handle is made of 17-4PH precipitation-type stainless steel.

3. The hardening treatment process for brazed steel connecting handles of a cemented carbide valve stem according to claim 1, characterized in that: In step one, the heating rate of the muffle furnace is 5-10℃ / min until it reaches 1040-1060℃.

4. The hardening process for brazing a cemented carbide valve stem steel connecting handle according to claim 1, characterized in that: The solder is a silver-copper three-layer structure solder with the composition of Ag20+BCu58+Ag20, and the brazing temperature of the solder is greater than 800℃.

5. The hardening treatment process for brazed steel connecting handles of a cemented carbide valve stem according to claim 1, characterized in that: In step three, the organic solvent is alcohol, acetone, or gasoline.

6. The hardening treatment process for the brazed steel connecting handle of a cemented carbide valve stem according to claim 5, characterized in that: In step five, the holding time for high-frequency induction brazing is 1-3 minutes.

7. The hardening treatment process for brazed steel connecting handles of a cemented carbide valve stem according to claim 1, characterized in that: In step six, the muffle furnace heats up at a rate of 3-8°C / min until it reaches 450-460°C.

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