CN109702292B - Welding process of VAR titanium alloy ingot - Google Patents
Welding process of VAR titanium alloy ingot Download PDFInfo
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Abstract
The invention relates to a welding process of a VAR titanium alloy ingot, which comprises the following steps: 1) sequentially assembling a plurality of large-sized cast ingots in a crucible in a way that the heads of the large-sized cast ingots face downwards and the bottoms of the large-sized cast ingots face upwards; 2) installing an auxiliary electrode on the pneumatic chuck of the electrode rod, placing the crucible in a vacuum consumable arc furnace, sealing the furnace and evacuating; 3) welding the auxiliary electrode and the cast ingot in the step 1) at the head in a vacuum consumable arc furnace; 4) the middle part of the cast ingot is welded with the middle part of the cast ingot; and controlling parameters such as current, voltage, arc stabilization and the like in the welding process in the step 3) and the step 4), so that the problems of poor quality stability, insufficient welding area, poor smelting safety, poor quality stability and the like of the welding seam of the conventional cast ingot with the phi 820mm specification are solved.
Description
Technical Field
The invention belongs to the technical field of nonferrous metal processing, and particularly relates to a welding process of a VAR titanium alloy ingot with a phi 820mm specification.
Background
Vacuum consumable arc melting (VAR) has become the mainstream method for producing titanium alloy ingots, and titanium alloy ingots generally need to be remelted twice to three times to obtain good ingot quality. Combination welding is usually carried out in a vacuum consumable arc furnace, and the invention patent with the publication number of CN105611663A in the prior art relates to an electrode for the vacuum consumable arc furnace, a welding method of the electrode and a method for carrying out vacuum consumable smelting feeding by using the electrode, wherein the electrode for the vacuum consumable arc furnace comprises a consumable electrode and an auxiliary electrode, and is characterized in that a transition electrode is connected between the consumable electrode and the auxiliary electrode. Although the electrode for the vacuum consumable electrode furnace can effectively reduce the operation cost, improve the ingot forming rate and improve the quality of the feeding end face of the ingot, the patent does not relate to the pre-vacuum control, leakage rate control, arc stabilizing current magnitude, welding voltage adjustment and middle welding process parameters between the ingot and the auxiliary electrode when the auxiliary electrode and the consumable electrode are welded, the welding process, particularly middle welding, has higher requirements on operators, and the parameters of current, voltage, arc stabilizing and the like need to be continuously adjusted according to actual conditions in the welding process, so that the operation process is complex. And with the increase of ingot specification, because the ingot to be welded is heated unevenly for a short time, the welding difficulty is correspondingly increased, the quality stability of welding seams is poor, observation after the welding seams of the ingot with the specification of phi 820mm are longitudinally cut along the diameter direction shows that the effective welding area is often less than 30%, and in the subsequent ingot smelting process, the welding seams have the risk of thermal cracking due to the insufficient welding area, so that the smelting safety and the ingot quality stability are influenced.
Disclosure of Invention
The invention aims to provide a welding process of a phi 820mm specification VAR titanium alloy ingot, which solves the problems of poor welding seam quality stability, insufficient welding area, poor smelting safety, poor ingot quality stability and the like of the conventional phi 820mm specification ingot.
The invention relates to a welding process of a VAR titanium alloy ingot, which specifically comprises the following steps:
1) sequentially assembling a plurality of large-sized cast ingots in a crucible in a way that the heads of the large-sized cast ingots face downwards and the bottoms of the large-sized cast ingots face upwards;
2) installing an auxiliary electrode on the pneumatic chuck of the electrode rod, placing the crucible in a vacuum consumable arc furnace, sealing the furnace and evacuating;
3) welding the auxiliary electrode and the cast ingot in the step 1) at the head in a vacuum consumable arc furnace;
4) and after the head welding is finished and cooled, middle welding is carried out.
Further, according to the preparation method, the large-size cast ingot in the step 1) is a phi 820 mm-sized cast ingot.
Further, in the preparation method, in the step 1), the pre-vacuum is controlled to be 1.0-5.0 Pa in the welding process, and the leakage rate is controlled to be 0.5-1.0 Pa/min, so that the oxidation of the welding seam of the electrode can be prevented, and the influence on the quality of the subsequent ingot casting can be avoided.
Further, according to the preparation method, the welding current and the welding time of the auxiliary electrode and the head of the ingot in the step 3) are carried out according to the set value of 3kA/2min → 5kA/4min → 9kA/3min → 11kA/2min, the welding voltage is kept at 22-30V, the arc stabilizing current adopts 3-20A direct current, and the head is cooled for 30-40 min after being welded.
Further, according to the preparation method, the middle welding current and the holding time between the cast ingots in the step 4) are carried out according to a set value of 4kA/5min → 7kA/8min → (9-13) kA/(10-15) min → 16kA/4min, the welding voltage is kept at 22-32V, the arc stabilizing current is direct current of 3-25A, and the middle part is cooled for 40-60 min after welding. The middle welding current is controlled to be 4-16 kA, so that the stability of the welding process is ensured, the middle welding time is controlled to be 27-32 min, and the purpose that enough heat is accumulated and the welding strength is increased after the end face of the ingot to be welded is baked for a long time is ensured. The middle welding voltage is controlled to be 22-32V, abnormal conditions such as severe splashing of a welding molten pool and the like caused by unreasonable voltage parameter setting in the welding process are avoided, the middle welding arc stabilizing current is set to be 3-25A direct current, the welding arc light is enabled to uniformly move on the end face of an ingot to be welded, the end face of the ingot is enabled to be uniformly heated, the welding molten pool is restrained, and welding failure caused by overflow of the molten pool is avoided. And the middle part is cooled for 40-60 min after welding, so that the problem that the quality of the cast ingot is influenced due to oxidation of a welding seam part caused by insufficient cooling time after welding is avoided.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention provides a welding process of a VAR titanium alloy cast ingot with a phi 820mm specification, which is characterized in that an auxiliary electrode and the cast ingot are welded in a vacuum consumable arc furnace, and parameters such as optimal pre-vacuum, leak rate, welding current, voltage, arc stabilization, cooling time and the like are determined according to actual conditions in the welding process, so that the problems of poor quality stability, insufficient welding area, poor smelting safety, poor quality stability of the cast ingot and the like of the conventional cast ingot with the phi 820mm specification in welding weld joint are solved.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
The welding process of the VAR titanium alloy ingot comprises the following steps: the method specifically comprises the following steps:
1) sequentially assembling a plurality of phi 820mm cast ingots in a phi 920mm crucible in a mode that the heads of the cast ingots are downward and the bottoms of the cast ingots are upward;
2) installing an auxiliary electrode on the pneumatic chuck of the electrode rod, placing the crucible in a vacuum consumable arc furnace, sealing the furnace and evacuating;
3) welding the auxiliary electrode and the cast ingot in the step 1) at the head in a vacuum consumable arc furnace, controlling the pre-vacuum in the welding process to be 1.0-5.0 Pa, controlling the leakage rate to be 0.5-1.0 Pa/min, controlling the welding current and time of the auxiliary electrode and the head of the cast ingot to be carried out according to the set value of 3kA/2min → 5kA/4min → 9kA/3min → 11kA/2min, keeping the welding voltage at 22-30V, adopting 3-20A direct current for arc stabilizing current, and cooling the head for 30-40 min after welding;
4) the middle welding current and the holding time between the cast ingots are carried out according to the set value of 4kA/5min → 7kA/8min → (9-13) kA/(10-15) min → 16kA/4min, the welding voltage is kept at 22-32V, the arc stabilizing current adopts 3-25A direct current, and the middle part is cooled for 40-60 min after welding.
The pre-vacuum is controlled to be 1.0 Pa-5.0 Pa in the welding process, and the leakage rate is controlled to be 0.5 Pa/min-1.0 Pa/min, so that the oxidation of the welding seam of the electrode is prevented, and the quality of the subsequent ingot casting is prevented from being influenced;
the middle welding current is controlled to be 4-16 kA, so that the stability of the welding process is ensured, the middle welding time is controlled to be 27-32 min, and the sufficient heat is accumulated after the end face of the ingot to be welded is baked for a long time. The middle welding voltage is controlled to be 22-32V, abnormal conditions such as severe splashing of a welding molten pool and the like caused by unreasonable voltage parameter setting in the welding process are avoided, the middle welding arc stabilizing current is set to be 3-25A direct current, the welding arc light is enabled to uniformly move on the end face of an ingot to be welded, the end face of the ingot is enabled to be uniformly heated, the welding molten pool is restrained, and welding failure caused by overflow of the molten pool is avoided.
And the middle part is cooled for 40-60 min after welding, so that the problem that the quality of the cast ingot is influenced due to oxidation of a welding seam part caused by insufficient cooling time after welding is avoided.
Example 1
1) Sequentially assembling a plurality of phi 820mm cast ingots in a phi 920mm crucible in a mode that the heads of the cast ingots are downward and the bottoms of the cast ingots are upward;
2) installing an auxiliary electrode on the pneumatic chuck of the electrode rod, placing the crucible in a vacuum consumable arc furnace, and sealing the furnace for evacuation;
3) welding the auxiliary electrode and the cast ingot head in a vacuum consumable arc furnace, controlling the pre-vacuum to be 1.0-5.0 Pa in the welding process, controlling the leakage rate to be 0.5-1.0 Pa/min, specifically setting the welding current and time of the auxiliary electrode and the cast ingot head according to parameters as shown in table 1, and cooling the head for 30min after welding;
TABLE 1 ingot head weld parameter set
| Step (ii) of | current/kA | voltage/V | Arc stabilization/A | Time/min |
| 1 | 3.00 | 23 | 6 | 2 |
| 2 | 5.00 | 24 | 7 | 4 |
| 3 | 9.00 | 25 | 10 | 3 |
| 4 | 11.00 | 27 | 12 | 2 |
4) The welding current in the middle between the cast ingots is shown in table 2, and the middle is cooled for 45min after welding.
TABLE 2 ingot middle weld parameter settings
| Step (ii) of | current/Ka. | voltage/V | Arc stabilization/A | Time/min |
| 1 | 4.00 | 23 | 6 | 5 |
| 2 | 7.00 | 24 | 10 | 8 |
| 3 | 9.00 | 27 | 15 | 15 |
| 4 | 16.00 | 29 | 21 | 4 |
After cooling the cast ingot with the diameter of 820mm welded in the embodiment for 45min, the weld quality is checked, the weld at the head part and the middle part is silvery white metallic luster, the weld pool is full, and the upper part and the lower part are in a molten adhesion state. The head welding seam and the middle welding seam are respectively sawed and longitudinally cut along the diameter, the effective welding adhesion area of the head welding seam is 100 percent, and the effective welding adhesion area of the middle welding seam is 100 percent.
Example 2
1) Sequentially assembling a plurality of phi 820mm cast ingots in a phi 920mm crucible in a mode that the heads of the cast ingots are downward and the bottoms of the cast ingots are upward;
2) installing an auxiliary electrode on the pneumatic chuck of the electrode rod, placing the crucible in a vacuum consumable arc furnace, and sealing the furnace for evacuation;
3) welding the auxiliary electrode and the cast ingot head in a vacuum consumable arc furnace, controlling the pre-vacuum in the welding process to be 1.0-5.0 Pa, controlling the leakage rate to be 0.5-1.0 Pa/min, controlling the welding current and time of the auxiliary electrode and the cast ingot head to be as shown in a table 3, and cooling the head for 40min after welding;
TABLE 3 ingot head weld parameter settings
| Step (ii) of | current/kA | voltage/V | Arc stabilization/A | Time/min |
| 1 | 3.00 | 23 | 6 | 2 |
| 2 | 5.00 | 24 | 7 | 4 |
| 3 | 9.00 | 25 | 10 | 3 |
| 4 | 11.00 | 27 | 12 | 2 |
And 4, step 4: the welding current in the middle between the cast ingots is shown in table 4, and the middle is cooled for 50min after welding.
TABLE 4 ingot middle weld parameter settings
| Step (ii) of | current/Ka. | voltage/V | Arc stabilization/A | Time/min |
| 1 | 4.00 | 23 | 6 | 5 |
| 2 | 7.00 | 24 | 10 | 8 |
| 3 | 10.00 | 27 | 15 | 12 |
| 4 | 16.00 | 29 | 21 | 4 |
After cooling the cast ingot with the diameter of 820mm welded in the embodiment 2 for 50min, the weld quality is checked, the weld at the head part and the middle part is silvery white metallic luster, no oxidation trace exists, the weld pool is full, and the upper part and the lower part are in a molten adhesion state. The head welding seam and the middle welding seam are respectively sawed and longitudinally cut along the diameter, the effective welding adhesion area of the head welding seam is 100 percent, and the effective welding adhesion area of the middle welding seam is 95 percent.
Example 3
1) Sequentially assembling a plurality of phi 820mm cast ingots in a phi 920mm crucible in a mode that the heads of the cast ingots are downward and the bottoms of the cast ingots are upward;
2) installing an auxiliary electrode on the pneumatic chuck of the electrode rod, placing the crucible in a vacuum consumable arc furnace, and sealing the furnace for evacuation;
3) welding the auxiliary electrode and the cast ingot head in a vacuum consumable arc furnace, controlling the pre-vacuum in the welding process to be 1.0-5.0 Pa, controlling the leakage rate to be 0.5-1.0 Pa/min, controlling the welding current and time of the auxiliary electrode and the cast ingot head to be as shown in a table 5, and cooling the head for 35min after welding;
TABLE 5 ingot head weld parameter settings
| Step (ii) of | current/kA | voltage/V | Arc stabilization/A | Time/min |
| 1 | 3.00 | 23 | 6 | 2 |
| 2 | 5.00 | 24 | 7 | 4 |
| 3 | 9.00 | 25 | 10 | 3 |
| 4 | 11.00 | 27 | 12 | 2 |
And 4, step 4: the welding current in the middle between the cast ingots is shown in table 6, and the middle is cooled for 60min after welding.
TABLE 6 ingot middle weld parameter settings
| Step (ii) of | current/Ka. | voltage/V | Arc stabilization/A | Time/min |
| 1 | 4.00 | 23 | 6 | 5 |
| 2 | 7.00 | 24 | 10 | 8 |
| 3 | 13.00 | 27 | 15 | 10 |
| 4 | 16.00 | 29 | 21 | 4 |
The cast ingot with the diameter of 820mm welded in the embodiment is cooled for 60min, then the weld joint quality is checked, the weld joints at the head part and the middle part are silvery white metallic luster, the weld joint molten pool is full, and the upper part and the lower part are in a molten adhesion state. The head welding seam and the middle welding seam are respectively sawed and longitudinally cut along the diameter, the effective welding adhesion area of the head welding seam is 100 percent, and the effective welding adhesion area of the middle welding seam is 100 percent.
Claims (3)
1. A welding process of a VAR titanium alloy ingot is characterized by comprising the following steps:
1) sequentially assembling a plurality of large-sized cast ingots in a crucible in a way that the heads of the large-sized cast ingots face downwards and the bottoms of the large-sized cast ingots face upwards;
2) installing an auxiliary electrode on the pneumatic chuck of the electrode rod, placing the crucible in a vacuum consumable arc furnace, sealing the furnace and evacuating;
3) welding the auxiliary electrode and the cast ingot in the step 1) at the head in a vacuum consumable arc furnace;
4) after the head welding is finished and cooled, middle welding is carried out;
the middle welding current and the holding time between the cast ingots in the step 4) are carried out according to the set value of 4kA/5min → 7kA/8min → (9-13) kA/(10-15) min → 16kA/4min, the welding voltage is kept at 22-32V, the arc stabilizing current adopts 3-25A direct current, and the middle part is cooled for 40-60 min after welding;
and 3) welding current and time between the auxiliary electrode and the head of the ingot casting are carried out according to the set value of 3kA/2min → 5kA/4min → 9kA/3min → 11kA/2min, the welding voltage is kept at 22-30V, the arc stabilizing current is 3-20A direct current, and the head is cooled for 30-40 min after welding.
2. The welding process of claim 1, wherein the large format ingot of step 1) is a Φ 820mm format ingot.
3. The welding process of claim 1, wherein the pre-vacuum in the welding process of step 3) is controlled to be 1.0-5.0 Pa, and the leak rate is controlled to be 0.5-1.0 Pa/min.
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Inventor after: Hua Zhengli Inventor after: Liu Xianghong Inventor after: Shang Jinjin Inventor after: Liu Peng Inventor after: Luo Wenzhong Inventor after: Yang Chao Inventor after: Zhang Xiaoming Inventor after: Zhang Jun Inventor after: Feng Xiaofei Inventor after: Wang Kaixuan Inventor before: Hua Zhengli Inventor before: Liu Peng Inventor before: Luo Wenzhong Inventor before: Yang Chao Inventor before: Zhang Xiaoming Inventor before: Zhang Jun Inventor before: Feng Xiaofei Inventor before: Wang Kaixuan Inventor before: Liu Xianghong |