Cobalt-based alloy welding wire for hot forging die and manufacturing method of cobalt-based alloy welding wire

Abstract

The invention discloses a cobalt-based alloy welding wire for a hot forging die and a manufacturing method of the cobalt-based alloy welding wire, and particularly relates to the field of hard-surface surfacing welding materials, and the cobalt-based alloy welding wire comprises the following chemical components in percentage by mass: 0.9-1.2% of C, 26.0-28.0% of Cr, 3.5-4.5% of W, less than or equal to 1.0% of Fe, less than or equal to 3.0% of Ni, 0.5-1.0% of S i, less than or equal to 0.5% of Mn, less than or equal to 0.5% of Mo, less than or equal to 0.015% of P, less than or equal to 0.015% of S and the balance of Co. After the improved cobalt-based alloy welding wire is subjected to surfacing of the hot forging die, the hardness is uniform and moderate, a surfacing layer is not prone to cracking and stripping in the using process of the hot forging die, the service life of the hot forging die is 35000-50000 times, the problems that an existing welding wire is uneven in hardness and prone to cracking after surfacing are solved, the service life of the hot forging die is remarkably prolonged, and the production cost is reduced. The improved welding wire has excellent hardness uniformity, impact toughness and cracking resistance, and the service life of a hot forging die can be remarkably prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of hardfacing welding materials, and more particularly to a cobalt-based alloy welding wire for a hot forging die and a manufacturing method thereof. Background Art

[0002] At present, surfacing cobalt-based alloys on the surface of hot forging dies can increase the service life of the dies. The technical indicators of hot forging die surfacing are relatively high: the welding wire alloy has high cleanliness, the hardness of the cladding metal after surfacing is uniform and the hardness range is narrow, and it has good impact toughness. Due to the general cleanliness and wide hardness range of conventional ERCoCr-A cobalt-based welding wire, the surfacing layer of the hot forging die is prone to cracking and peeling during use after surfacing conventional ERCoCr-A cobalt-based welding wire. In order to improve the wear resistance and thermal fatigue resistance of the die, surfacing technology is usually used to repair or strengthen its surface. At present, cobalt-based alloy welding wire (such as ERCoCr-A) is a commonly used material for hot forging die surfacing, but it has the following problems:

[0003] Uneven hardness: The hardness after surfacing fluctuates greatly (38-45HRC), which exceeds the ideal range required by hot forging dies (39-42HRC);

[0004] Insufficient impact toughness: High hardness areas (>43HRC) easily lead to increased brittleness of the cladding layer, which is prone to cracking and peeling during use;

[0005] Short service life: The service life of the hot forging die of traditional wire surfacing is only 10,000-30,000 times, which is difficult to meet the needs of efficient production;

[0006] In the existing technology, the content of elements such as Cr and W in conventional cobalt-based welding wires fluctuates greatly, affecting the hardness and toughness of the weld overlay layer; impurities (such as P and S) are easily introduced during the smelting process, resulting in low cleanliness of the welding wire and decreased performance of the weld overlay layer; the existing technology does not design the welding wire composition and process based on the working conditions of the hot forging die (high temperature impact and thermal fatigue).

[0007] Therefore, it is necessary to develop a cobalt-based alloy welding wire with good surfacing performance, moderate hardness after welding, and good impact toughness of the surfacing layer and a manufacturing method thereof. Summary of the Invention

[0008] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a cobalt-based alloy welding wire for a hot forging die and a method for manufacturing the same. The technical problems to be solved by the present invention are: the hardness of the cobalt-based alloy welding wire for a hot forging die is uneven and exceeds the standard after surfacing welding, the surfacing layer is prone to cracking and peeling during the use of the hot forging die, and the service life is short, as well as a method for manufacturing the welding wire.

[0009] To achieve the above-mentioned object, the present invention provides the following technical solution: a cobalt-based alloy welding wire for a hot forging die, whose chemical composition, by mass percentage, includes: C 0.9-1.2%, Cr 26.0-28.0%, W 3.5-4.5%, Fe≤1.0%, Ni≤3.0%, Si 0.5-1.0%, Mn≤0.5%, Mo≤0.5%, P≤0.015%, S≤0.015%, and Co as the balance.

[0010] In a preferred embodiment, the raw materials are preferably prepared by adding corresponding industrial grade pure metals, wherein the raw materials require: the purity of metal Co (cobalt) is ≥99.5%, and the purity of metal Cr (chromium) is ≥99.4%.

[0011] The present invention also includes a method for manufacturing a cobalt-based alloy welding wire for a hot forging die, and the specific preparation steps are as follows:

[0012] Step S1, alloy batching: prepare the above elements in proportion and take the middle limit of the chemical composition range as the target value;

[0013] Step S2, vacuum melting and ingot casting: vacuum melting the prepared alloy raw materials, with the melting quantity per furnace being ≤30kg;

[0014] Step S3, argon-protected melting and deoxidation and slag removal in a medium-frequency furnace: the vacuum-melted ingot is loaded into a medium-frequency horizontal continuous casting furnace for melting, argon protection is introduced into the medium-frequency horizontal continuous casting furnace, Ca-Si powder is added for diffusion deoxidation, the molten pool is calmed for 10 minutes, a slag remover is added for slag removal, and samples are taken for chemical analysis. When the chemical composition meets the requirements, horizontal continuous casting is started;

[0015] Step S4, horizontal continuous casting: During the horizontal continuous casting process, argon gas is continuously introduced into the horizontal continuous casting furnace for protection, the molten pool temperature in the furnace is maintained at 1530±10°C, and the water flow rate in the crystallizer is controlled at 35-45 L / min;

[0016] Step S5, welding wire straightening: straighten the horizontally continuously cast welding wire, and control the straightness error within ±3 mm to obtain a cobalt-based alloy welding wire.

[0017] In a preferred embodiment, the temperature during the vacuum melting and refining period in step S2 is controlled at 1550±10°C, the vacuum degree is ≤1.0 Pa, and the melting time is ≥1.0 h.

[0018] In a preferred embodiment, the continuous casting furnace smelting time in step S3 is ≥1.0 h, and the smelting temperature is set to 1540±10°C.

[0019] The present invention also includes a method for strengthening the surface of a hot forging die, wherein the thickness of the surfacing layer is 3.0-5.0 mm; after surfacing, the temperature is kept at 350°C for 5-10 hours, and then cooled to room temperature with the furnace. The hardness of the obtained welding wire surfacing layer is 39-42 HRC, and the service life of the hot forging die after the welding wire surfacing is 35,000-50,000 times.

[0020] In a preferred embodiment, the surfacing welding is performed by gas shielded welding, and the shielding gas is set to pure argon or a mixture of argon and carbon dioxide; the preheating temperature of the surfacing welding is 300-400°C.

[0021] Technical effects and advantages of the present invention:

[0022] 1. The present invention uses an improved cobalt-based alloy welding wire for hot forging die surfacing, resulting in uniform and moderate hardness. The surfacing layer is not prone to cracking or peeling during use of the hot forging die, and the service life of the hot forging die is 35,000-50,000 times. This solves the problem of uneven hardness and easy cracking after surfacing with existing welding wires, and significantly improves the service life of the hot forging die.

[0023] 2. In the present invention, C is used together with Cr and W to form hard carbides to improve wear resistance, but excessive amount will lead to increased brittleness; the Cr component enhances oxidation resistance and corrosion resistance; improves high-temperature strength and red hardness, and optimizes the thermal fatigue resistance of the hot forging die; reduces the adverse effects of impurities on impact toughness, and the improved welding wire has excellent hardness uniformity, impact toughness and crack resistance, which can significantly increase the service life of the hot forging die. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] Example 1:

[0026] The present invention provides a cobalt-based alloy welding wire for a hot forging die, wherein the chemical composition of the cobalt-based alloy welding wire comprises, by mass percentage, C 0.9-1.2%, Cr 26.0-28.0%, W 3.5-4.5%, Fe ≤ 1.0%, Ni ≤ 3.0%, Si 0.5-1.0%, Mn ≤ 0.5%, Mo ≤ 0.5%, P ≤ 0.015%, S ≤ 0.015%, with Co as the balance, and corresponding industrial-grade pure metals are added, wherein the raw material requirements are: the purity of metal Co (cobalt) is ≥ 99.5%, and the purity of metal Cr (chromium) is ≥ 99.4%;

[0027] Specifically in this embodiment, the chemical composition, by mass percentage, includes: C 0.95%, Cr 26.05%, W 3.79%, Fe 0.58%, Ni 2.62%, Si 0.76%, Mn 0.03%, Mo 0.01%, P 0.007%, S 0.001%, and Co is the balance to prepare the alloy according to the target value.

[0028] The present invention also includes a method for manufacturing a cobalt-based alloy welding wire for a hot forging die, and the specific preparation steps are as follows:

[0029] Step S1, alloy batching: prepare the above elements in proportion and take the middle limit of the chemical composition range as the target value;

[0030] Step S2, vacuum melting and ingot casting: vacuum melting the prepared alloy raw materials, with the melting quantity per furnace ≤30kg, the temperature during vacuum melting and refining being controlled at 1550±10℃, the vacuum degree ≤1.0Pa, and the melting time ≥1.0h;

[0031] Step S3, argon-protected melting and deoxidation and slag removal in a medium-frequency furnace: the vacuum-melted ingot is loaded into a medium-frequency horizontal continuous casting furnace for melting. Argon gas is introduced into the medium-frequency horizontal continuous casting furnace for protection. The melting time is ≥1.0 h, the melting temperature is set to 1540±10° C., Ca-Si powder is added for diffusion deoxidation, the molten pool is calmed for 10 min, a slag remover is added for slag removal, and samples are taken for chemical analysis. When the chemical composition meets the requirements, horizontal continuous casting is started;

[0032] Step S4, horizontal continuous casting: During the horizontal continuous casting process, argon gas is continuously introduced into the horizontal continuous casting furnace for protection, the molten pool temperature in the furnace is maintained at 1530±10°C, and the water flow rate in the crystallizer is controlled at 35-45 L / min;

[0033] Step S5, welding wire straightening: straighten the horizontally continuously cast welding wire, and control the straightness error within ±3 mm to obtain a cobalt-based alloy welding wire.

[0034] The present invention also includes a hot forging die surface strengthening method, which sets the thickness of the surfacing layer to 3.0-5.0 mm; after surfacing, the temperature is kept at 350°C for 5-10 hours, and then cooled to room temperature with the furnace. During the surfacing, a protective gas is introduced for shielded welding, and the protective gas is set to pure argon or a mixture of argon and carbon dioxide; the preheating temperature of the surfacing is 300-400°C.

[0035] Example 2:

[0036] The present invention provides a cobalt-based alloy welding wire for a hot forging die, wherein the chemical composition of the cobalt-based alloy welding wire comprises, by mass percentage, C 0.9-1.2%, Cr 26.0-28.0%, W 3.5-4.5%, Fe ≤ 1.0%, Ni ≤ 3.0%, Si 0.5-1.0%, Mn ≤ 0.5%, Mo ≤ 0.5%, P ≤ 0.015%, S ≤ 0.015%, with Co as the balance, and corresponding industrial-grade pure metals are added, wherein the raw material requirements are: the purity of metal Co (cobalt) is ≥ 99.5%, and the purity of metal Cr (chromium) is ≥ 99.4%;

[0037] Specifically in this embodiment, the chemical composition, by mass percentage, includes: C 0.99%, Cr 26.10%, W 3.80%, Fe 0.43%, Ni 2.60%, Si 0.78%, Mn 0.02%, Mo 0.01%, P 0.006%, S 0.001%, and Co is the balance to prepare the alloy according to the target value.

[0038] The present invention also includes a method for manufacturing a cobalt-based alloy welding wire for a hot forging die, and the specific preparation steps are as follows:

[0039] Step S1, alloy batching: prepare the above elements in proportion and take the middle limit of the chemical composition range as the target value;

[0040] Step S2, vacuum melting and ingot casting: vacuum melting the prepared alloy raw materials, with the melting quantity per furnace ≤30kg, the temperature during vacuum melting and refining being controlled at 1550±10℃, the vacuum degree ≤1.0Pa, and the melting time ≥1.0h;

[0041] Step S3, argon-protected melting and deoxidation and slag removal in a medium-frequency furnace: the vacuum-melted ingot is loaded into a medium-frequency horizontal continuous casting furnace for melting. Argon gas is introduced into the medium-frequency horizontal continuous casting furnace for protection. The melting time is ≥1.0 h, the melting temperature is set to 1540±10° C., Ca-Si powder is added for diffusion deoxidation, the molten pool is calmed for 10 min, a slag remover is added for slag removal, and samples are taken for chemical analysis. When the chemical composition meets the requirements, horizontal continuous casting is started;

[0042] Step S4, horizontal continuous casting: During the horizontal continuous casting process, argon gas is continuously introduced into the horizontal continuous casting furnace for protection, the molten pool temperature in the furnace is maintained at 1530±10°C, and the water flow rate in the crystallizer is controlled at 35-45 L / min;

[0043] Step S5, welding wire straightening: straighten the horizontally continuously cast welding wire, and control the straightness error within ±3 mm to obtain a cobalt-based alloy welding wire.

[0044] The present invention also includes a hot forging die surface strengthening method, which sets the thickness of the surfacing layer to 3.0-5.0 mm; after surfacing, the temperature is kept at 350°C for 5-10 hours, and then cooled to room temperature with the furnace. During the surfacing, a protective gas is introduced for shielded welding, and the protective gas is set to pure argon or a mixture of argon and carbon dioxide; the preheating temperature of the surfacing is 300-400°C.

[0045] Example 3:

[0046] The present invention provides a cobalt-based alloy welding wire for a hot forging die, wherein the chemical composition of the cobalt-based alloy welding wire comprises, by mass percentage, C 0.9-1.2%, Cr 26.0-28.0%, W 3.5-4.5%, Fe ≤ 1.0%, Ni ≤ 3.0%, Si 0.5-1.0%, Mn ≤ 0.5%, Mo ≤ 0.5%, P ≤ 0.015%, S ≤ 0.015%, with Co as the balance, and corresponding industrial-grade pure metals are added, wherein the raw material requirements are: the purity of metal Co (cobalt) is ≥ 99.5%, and the purity of metal Cr (chromium) is ≥ 99.4%;

[0047] Specifically in this embodiment, the chemical composition, by mass percentage, includes: C 0.97%, Cr 26.34%, W 3.82%, Fe 0.60%, Ni 2.64%, Si 0.90%, Mn 0.02%, Mo 0.01%, P 0.006%, S 0.001%, and Co is the balance to prepare the alloy according to the target value.

[0048] The present invention also includes a method for manufacturing a cobalt-based alloy welding wire for a hot forging die, and the specific preparation steps are as follows:

[0049] Step S1, alloy batching: prepare the above elements in proportion and take the middle limit of the chemical composition range as the target value;

[0050] Step S2, vacuum melting and ingot casting: vacuum melting the prepared alloy raw materials, with the melting quantity per furnace ≤30kg, the temperature during vacuum melting and refining being controlled at 1550±10℃, the vacuum degree ≤1.0Pa, and the melting time ≥1.0h;

[0051] Step S3, argon-protected melting and deoxidation and slag removal in a medium-frequency furnace: the vacuum-melted ingot is loaded into a medium-frequency horizontal continuous casting furnace for melting. Argon gas is introduced into the medium-frequency horizontal continuous casting furnace for protection. The melting time is ≥1.0 h, the melting temperature is set to 1540±10° C., Ca-Si powder is added for diffusion deoxidation, the molten pool is calmed for 10 min, a slag remover is added for slag removal, and samples are taken for chemical analysis. When the chemical composition meets the requirements, horizontal continuous casting is started;

[0052] Step S4, horizontal continuous casting: During the horizontal continuous casting process, argon gas is continuously introduced into the horizontal continuous casting furnace for protection, the molten pool temperature in the furnace is maintained at 1530±10°C, and the water flow rate in the crystallizer is controlled at 35-45 L / min;

[0053] Step S5, welding wire straightening: straighten the horizontally continuously cast welding wire, and control the straightness error within ±3 mm to obtain a cobalt-based alloy welding wire.

[0054] The present invention also includes a hot forging die surface strengthening method, which sets the thickness of the surfacing layer to 3.0-5.0 mm; after surfacing, the temperature is kept at 350°C for 5-10 hours, and then cooled to room temperature with the furnace. During the surfacing, a protective gas is introduced for shielded welding, and the protective gas is set to pure argon or a mixture of argon and carbon dioxide; the preheating temperature of the surfacing is 300-400°C.

[0055] Example 4:

[0056] The alloy welding wires prepared in Examples 1-3 were respectively used for surface strengthening surfacing on hot forging dies, and the hardness of the surfacing layers was tested. The measured values of the main performance parameters are shown in Table 1 below:

[0057] Table 1

[0058]

[0059] Compared with the prior art, the advantages of the alloy welding wires prepared in Examples 1-3 are shown in Table 2 below:

[0060] Table 2

[0061]

[0062]

[0063] As can be seen from Table 1-2 above, the raw material components in Examples 1-3 are:

[0064] C (0.9-1.2%): forms hard carbides with Cr and W, improving wear resistance, but excessive amount will lead to increased brittleness;

[0065] Cr (26-28%): Enhances oxidation resistance and corrosion resistance, and forms M7C3 type carbides with C;

[0066] W (3.5-4.5%): Improves high-temperature strength and red hardness, and optimizes the thermal fatigue resistance of hot forging dies;

[0067] Low P and S (≤0.015%): reduce the adverse effects of impurities on impact toughness;

[0068] By optimizing the composition design and process control, the hardness of the cladding layer is stabilized at 39-42HRC, ensuring hardness uniformity and avoiding local embrittlement; reducing crack sensitivity, improving impact toughness, and extending the mold service life to 35,000-50,000 times; through vacuum melting, argon protection and other processes, the cleanliness and composition consistency of the welding wire are ensured, thereby ensuring process stability.

[0069] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A cobalt-based alloy welding wire for hot forging dies, characterized in that: Its chemical composition includes, by mass percentage, C 0.9-1.2%, Cr 26.0-28.0%, W 3.5-4.5%, Fe≤1.0%, Ni≤3.0%, Si 0.5-1.0%, Mn≤0.5%, Mo≤0.5%, P≤0.015%, S≤0.015%, and Co as the balance.

2. The cobalt-based alloy welding wire for hot forging dies according to claim 1, characterized in that: The raw materials are selected and matched with corresponding industrial grade pure metals, wherein the raw materials are required to have a purity of metal Co of ≥99.5% and a purity of metal Cr of ≥99.4%.

3. A method for manufacturing the cobalt-based alloy welding wire for hot forging dies according to any one of claims 1 to 2, characterized in that: The specific preparation steps are as follows: Step S1, alloy batching: prepare the above elements in proportion and take the middle limit of the chemical composition range as the target value; Step S2, vacuum melting and ingot casting: vacuum melting the prepared alloy raw materials, with the melting quantity per furnace being ≤30kg; Step S3, argon-protected melting and deoxidation and slag removal in a medium-frequency furnace: the vacuum-melted ingot is loaded into a medium-frequency horizontal continuous casting furnace for melting, argon protection is introduced into the medium-frequency horizontal continuous casting furnace, samples are taken for chemical analysis, Ca-Si powder is added for diffusion deoxidation, the molten pool is calmed for 10 minutes, and then a slag remover is added for slag removal. When the chemical composition meets the requirements, horizontal continuous casting is started; Step S4, horizontal continuous casting: During the horizontal continuous casting process, argon gas is continuously introduced into the horizontal continuous casting furnace for protection, the molten pool temperature in the furnace is maintained at 1530±10°C, and the water flow rate in the crystallizer is controlled at 35-45 L / min; Step S5, welding wire straightening: straighten the horizontally continuously cast welding wire, and control the straightness error within ±3 mm to obtain a cobalt-based alloy welding wire.

4. The method for manufacturing a cobalt-based alloy welding wire for hot forging dies according to claim 3, wherein: In the step S2, the temperature during the vacuum melting and refining period is controlled at 1550±10° C., the vacuum degree is ≤1.0 Pa, and the melting time is ≥1.0 h.

5. The method for manufacturing a cobalt-based alloy welding wire for hot forging dies according to claim 3, wherein: In step S3, the continuous casting furnace smelting time is ≥1.0h, and the smelting temperature is set to 1540±10°C.

6. A method for strengthening the surface of a hot forging die, comprising: surfacing the surface of the hot forging die with the cobalt-based alloy welding wire according to any one of claims 1 to 2, wherein: The thickness of the surfacing layer is 3.0-5.0mm; after surfacing, keep warm at 350℃ for 5-10h, and then cool to room temperature with the furnace.

7. A hot forging die surface strengthening method according to claim 6, characterized in that: The surfacing welding adopts gas shielded welding, and the shielding gas is set to pure argon or a mixed gas of argon and carbon dioxide; the preheating temperature of the surfacing welding is 300-400°C.

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