CN114632997A - Welding method for super-large-diameter vacuum consumable electrode bar - Google Patents

Abstract

The invention discloses a method for processing and welding an oversized-diameter vacuum consumable electrode bar, which is used for smelting a vacuum consumable ingot through a plurality of vacuum induction electrodes so as to solve the problems of head and tail segregation and insufficient ingot weight of a large-ingot type vacuum consumable ingot. The invention has the advantages that: after the welding is finished, the quality of the welding position of the electrode rod is inspected, and the welding position is full and has no defects of insufficient welding, no lack of welding, no welding gap and the like; and (3) carrying out low power test on the transverse steel billet of the finished product phi 1050mm vacuum consumable ingot, and grading the metal inclusions in the serious view field of the steel according to the ASTM E45D standard, wherein all the non-metal inclusions in the finished product forging stock meet the technical standard requirements.

Description

Welding method for super-large-diameter vacuum consumable electrode bar

Technical Field

The invention belongs to the technical field of special smelting, and relates to a welding method of an oversized-diameter vacuum consumable electrode rod, wherein the size of the electrode rod is larger than phi 800 mm.

Background

The vacuum induction furnace and the vacuum consumable electrode furnace are used as main smelting equipment in the special smelting field, provide high-quality materials for the national defense industry key field, and the products are applied to important fields such as aerospace and the like. A vacuum consumable electrode furnace is a remelting mode for purification and refining in a vacuum state, a single vacuum induction electrode and a transition electrode rod are welded and then fixed on a pull rod capable of moving at a constant speed (see figure 1), and the vacuum consumable electrode furnace is smelted at a constant speed in a high-temperature electric arc. At present, the maximum ingot type of the domestic double vacuum melting special steel ingot is phi 1050mm, and the maximum ingot weight is about 20 tons. According to the upgrading of equipment in the field of aviation, a large-size forging stock material of 900mm multiplied by 500mm starts to be smelted, according to the requirement of the forging ratio, a vacuum consumable ingot phi 1050mm needs to be smelted urgently, the section of the steel ingot smelted by the vacuum induction furnace and the vacuum consumable furnace is increased continuously, the segregation tendency of the vacuum consumable ingot is increased, and the smelting difficulty is increased. According to market demands, the size and weight of the current vacuum induction furnace and vacuum consumable melting steel ingot can not meet the use requirements under the condition of a limit degree, and through anatomical simulation analysis on the phi 1050mm steel ingot, after the phi 1050mm steel ingot is forged, positive segregation exists in the induction electrode shrinkage cavity end component corresponding to the phi 1050mm steel ingot, negative segregation exists in the bottom pad end component, and the blank performance difference of the head and tail positions is large. Under the conditions that technological parameters such as different smelting speeds, arc lengths and the like are adjusted in a vacuum consumable electrode furnace and helium cooling is added, the segregation condition of phi 1050mm ingot-shaped components is still not improved; and the weight of the vacuum consumable steel ingot smelted by the single vacuum induction electrode can not meet the urgent market demand of large ingot type steel ingots, and the problem to be solved is urgent.

Disclosure of Invention

The invention discloses a welding method of an oversized-diameter vacuum consumable electrode bar, which is used for smelting a vacuum consumable steel ingot through a plurality of vacuum induction electrodes so as to solve the problems of head and tail segregation and insufficient ingot weight of a large-ingot type vacuum consumable ingot.

The specific technical scheme is as follows:

the first step is as follows: knowing the components of the welding material, and observing the appearance of the welding end face of the electrode rod and the condition that the welding end face has no holes;

the second step: performing flat head operation on the vacuum induction electrode bar, and cutting by adopting a band saw;

the third step: polishing the cut end face of the electrode rod to ensure that the end face is flat and the inclination does not exceed 2 degrees;

the fourth step: carrying out vacuum consumable electrode furnace charging operation on the end-car rear electrode bar, carrying out verticality correction by using a horizontal ruler in the furnace charging process, and enabling the ring distance deviation between the crystallizer and the electrode bar to be less than 5 mm;

the fifth step: welding electrode bars in a vacuum consumable electrode furnace, wherein the vacuum degree before welding is required to be not more than 1Pa, the state of the electrode bars is observed by small current 6000A-8000A during arc striking, and the current 18000A is gradually increased until the electrode bars are melted;

sixthly, if the phenomena of severe splashing and flowing exist in a certain corner, repeatedly reducing the current by 1000-5000A, stabilizing the welding arc, and gradually increasing the current after the flowing at the notch is collected;

and seventhly, when the welding is mature, the molten liquid overflows around the electrode bar, more splashing occurs, the electrode bar to be welded is melted, and the current is adjusted to 20000-25000A for welding.

The invention has the advantages that:

after the welding is finished, the quality of the welding position of the electrode bar is inspected, and the welding position is full and has no defects of insufficient welding, non-welding, welding gaps and the like; and (3) carrying out low power test on the transverse steel billet of the finished product phi 1050mm vacuum consumable ingot, and grading the metal inclusions in the serious view field of the steel according to the ASTM E45D standard, wherein all the non-metal inclusions in the finished product forging stock meet the technical standard requirements.

Drawings

FIG. 1 is a schematic view of a single electrode weld;

FIG. 2 is a schematic view of a dual electrode weld;

FIG. 3 is a graph of a weld curve (properly adjusted for actual arcing);

FIG. 4 is a picture of a weld joint after welding of an electrode;

FIG. 5 is a vacuum consumable melting curve.

Reference numerals: 1-transition electrode bar, 2-welding seam position, 3-induction electrode bar, 4-welding seam position I, 5-induction electrode bar I, 6-welding seam position II, 7-induction electrode bar II, 8-welding seam.

Detailed description of the preferred embodiments

The invention is described in detail with reference to the accompanying drawings, wherein 300M steel is used as an embodiment, the steel is applied to the aviation field and is a high-strength steel material which is most widely applied as an aircraft landing gear material.

Examples

1. The production process comprises the following steps:

firstly, a vacuum induction furnace is adopted to smelt and produce a consumable electrode bar for vacuum consumable remelting, the specification of the electrode bar is phi 920mm, and the chemical components of the electrode meet the specification of table 1.

TABLE 1

And secondly, respectively cutting the flat ends of the vacuum induction electrode rod head and the tail.

And thirdly, performing end surface polishing on the cut vacuum induction electrode rod, wherein the inclination of the end surface is not more than 2 degrees.

And fourthly, carrying out vacuum consumable electrode furnace charging operation on the rear electrode bar of the end car, placing one electrode bar at the bottom of the crystallizer, welding the other electrode bar with the transition electrode bar (see the figure 1 and the figure 2), and carrying out verticality correction by using a horizontal ruler in the charging process, wherein the annular distance deviation between the crystallizer and the electrode is less than 5 mm.

Fifthly, after the vacuum consumable electrode furnace is sealed and pumped out until the vacuum degree is not more than 1Pa, the lower end surface of the upper electrode rod contacts with the upper end surface of the bottom electrode rod, then the electrode rod is started, the state of the electrode rod is observed by low current 6000A-8000A during the arc starting, the state of the arc is observed by gradually increasing the current to 18000A, and the electrode rod is heated to melt the electrode rod.

And sixthly, if the phenomena of severe splashing and flowing exist in a certain corner, reducing the current by 1000-5000A, stabilizing the welding arc, and gradually increasing the current after the flowing at the notch is received.

And seventhly, when the welding is mature, the molten liquid overflows around the electrode rod and is splashed more, and when the welding is mature, the electrode rod to be welded is melted to form the molten liquid. Adjusting the current to 20000A-25000A for welding.

(the welding process is shown in fig. 3).

Then, an electrode bar to be welded is smelted into an phi 1050mm ingot by using a vacuum consumable electrode furnace, and the filling ratio is controlled to be 0.80-0.90%.

2. And (3) verification and verification:

firstly, appearance verification:

after the welding is finished, the quality of the welding position of the electrode rod is inspected, and the welding position is full and has no defects such as insufficient solder, no welding joint, welding gaps and the like (see figure 4);

in the consumable melting process, the fluctuation range of the melting speed is less than 10%, and the influence of the welding position on the consumable process is small (see figure 5).

And secondly, quality inspection of finished products:

phi 1050mm vacuum consumable ingot transverse billet and forged to greater than 500 x 900mm finished product at a forging ratio of greater than 4:1, samples cut at 5% of the top and bottom of the bar, steel severe field metallic inclusions rated according to ASTM E45D method standard, results are shown in table 2,

TABLE 2

As can be seen from Table 2, all the nonmetallic inclusions in the finished forged blank meet the technical standard requirements.

Claims (1)

1. A welding method of an oversized-diameter vacuum consumable electrode rod is characterized in that the specific technical scheme of the processing and welding method is as follows:

the first step is as follows: knowing the components of the welding material, and observing the appearance of the welding end face of the electrode rod and the condition that the welding end face has no holes;

the second step is that: performing flat head operation on the vacuum induction electrode bar, and cutting by adopting a band saw;

the third step: polishing the cut end face of the electrode rod to ensure that the end face is flat and the inclination does not exceed 2 degrees;

the fourth step: carrying out vacuum consumable electrode furnace charging operation on the end-car rear electrode bar, carrying out verticality correction by using a horizontal ruler in the furnace charging process, and enabling the ring distance deviation between the crystallizer and the electrode bar to be less than 5 mm;

the fifth step: welding an electrode rod in a vacuum consumable furnace, wherein the vacuum degree before welding is required to be not more than 1Pa, starting arc, viewing the state of the electrode rod at a low current of 6000-8000A, and gradually increasing the current of 18000A until the electrode rod is melted;

sixthly, if the phenomena of severe splashing and flowing exist in a certain corner, repeatedly reducing the current by 1000-5000A, stabilizing the welding arc, and gradually increasing the current after the flowing at the notch is collected;

and seventhly, when the welding is mature, the molten liquid overflows around the electrode bar, more splashing occurs, the electrode bar to be welded is melted, and the current is adjusted to 20000-25000A for welding.

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