JP4967974B2 - Glass lubricant for hot extrusion, method for hot extrusion of metal material using the same, and method for manufacturing metal tube - Google Patents

Description

  The present invention is applicable to a hot-extrusion glass lubricant that can be applied to hot-extrusion of pipes, rods, molds, and the like, a hot-extrusion method of a metal material using the lubricant, and a metal pipe, particularly a seamless pipe. It relates to a suitable manufacturing method.

  Usually, a metal material made of alloy steel containing Cr, stainless steel, heat-resistant alloy, or the like is processed by a hot extrusion method typified by the Eugene Sejurne method using glass as a lubricant. Especially, the seamless pipe illustrated as a metal pipe is not limited to said steel type, but is manufactured by the hot extrusion pipe manufacturing method by the Eugene Sejurne method over a wide steel type which consists of carbon steel.

  FIG. 1 is a cross-sectional view illustrating a hot extrusion pipe making method used for the production of seamless pipes. A billet 8 (in the present specification, simply referred to as “hollow billet”) having a through-hole in the center is mounted in the container 6, and a die holder 4 and a die backer 5 are attached to one end of the container 6. The die 2 is detachably mounted via the. Further, the mandrel 3 is inserted into the through hole of the billet 8, and the dummy block 7 is disposed on the rear end surface thereof.

  In such a configuration, when the stem (not shown) is operated and the dummy block 7 is pressed in the direction of the white arrow, the billet 8 is upset and then pushed out from the annular gap formed by the die 2 and the mandrel 3. Thus, a seamless tube having an outer diameter corresponding to the inner diameter of the die 2 and an inner diameter corresponding to the outer diameter of the mandrel 3 is manufactured.

  In general, the glass used as a lubricant in the hot extrusion pipe making method shown in FIG. 1 is supplied after the hollow billet 8 which is a workpiece is heated to the extrusion temperature (usually 1000 to 1250 ° C.). .

  That is, the supply of the external lubricant for lubricating the inner surface of the container 6 and the outer surface of the billet 8 is performed by rolling and transferring the heated billet on a table on which powdered glass is dispersed and coating the outer surface of the billet with glass. Is called. In addition, the supply of the inner surface lubricant that lubricates the outer surface of the mandrel 3 and the inner surface of the billet 8 is performed by placing a semi-cylindrical spoon in the through-hole of the billet that is rotating on the turning roller or rolling on the table. It is performed by inserting and applying powdered glass and coating the billet inner surface with glass.

  On the other hand, the supply of the front lubricant for lubricating the inner surface of the die 2 mounted on the die holder 4 and the tip and outer surfaces of the hollow billet 8 is performed using an appropriate binder such as water glass as shown in FIG. This is done by fixing and attaching a glass disk 1 formed of glass powder in a hollow disk shape to the entrance side of the die 2.

In the processing of metal materials by the hot extrusion method, since the performance of the lubricant affects the quality properties of the workpiece, many proposals have been made regarding glass lubricants. For example, in Patent Document 1, in order to prevent seizure at the time of hot extrusion, glass formed by adding a solid lubricating powder to glass powder having a viscosity of 10 ⁵ poise or less in the temperature range of extrusion processing and adding a binder. A hot extrusion tube making method using a disk as a front lubricant is disclosed.

  Patent Document 2 has a specific composition, and an appropriate viscosity in the temperature range of the extrusion process is set to 300 to prevent seizure due to breakage of the glass layer due to low viscosity or seizure due to insufficient lubrication at high viscosity. A glass lubricant for hot extrusion with 3000 poise is disclosed.

In Patent Document 3, a fireproof material is applied to the billet surface in order to prevent indentation flaws and seizure due to scale in extrusion at a high degree of processing at an extrusion ratio of 30% or more. A metal material that is sometimes processed by melting a scale of the billet surface that is sometimes generated or adhered to the refractory material, and applying a glass lubricant having a viscosity of 10 ^1.5 to 10 ⁴ poise in the temperature range of the extrusion process. A hot extrusion method is disclosed.

Further, Patent Document 4 discloses that the front lubricant has a viscosity of 10 ³ poise or more to prevent the formation of vertical wrinkles on the outer surface, and the outer lubricant has a viscosity of 10 poise or less to reduce the friction coefficient. In particular, there has been disclosed a hot extrusion pipe making method that suppresses the occurrence of outer surface defects particularly in ferritic stainless steel pipes and duplex stainless steel pipes by preventing the occurrence of outer surface streaks.

  By using the glass lubricant proposed in the above Patent Documents 1 to 4, and further by adopting the hot extrusion pipe making method using these, external defects such as indentation flaws and seizure accompanying hot extrusion processing Generation | occurrence | production can be suppressed and it becomes possible to exhibit an expected effect.

Japanese Patent Laid-Open No. 06-170437 JP-A-11-92169 JP-A-11-123443 JP 2004-174536 A

  Usually, a seamless tube manufactured by a hot extrusion tube manufacturing method is cooled with water, and then the remaining glass is removed by pickling with boiling nitric acid and shot blasting. At this time, most of the glass remaining on the tube surface is peeled off by thermal shock by water cooling, and the remaining part not peeled off by pickling with boiling nitric acid is completely dissolved and removed.

  However, it takes time to pickle the glass that has not been peeled off by water cooling, and the remaining part of the glass is a part of the tube surface, so that most of the other parts are in a state of peracid washing. This causes problems such as rough skin and worsening yield. For this reason, in order to shorten the pickling time with boiling nitric acid and suppress the rough skin generated on the tube surface, it is desirable to remove all the remaining glass by water cooling.

  In the hot extrusion method, the glass also adheres to the inner surface of the container that restrains the outer surface of the workpiece to be extruded. The adhered glass solidifies after cooling and accumulates on the inner surface of the container. Usually, the glass adhering to the inner surface of the container is removed by water discharge or a removing jig (for example, a rotating brush). However, if the adhering glass is insufficiently removed, the remaining glass is removed from the outer surface of the workpiece. Cause. For this reason, it is necessary to remove easily the glass adhering to the container inner surface with water discharge or a removal jig.

  As described above, all of the conventionally proposed glass lubricants focus on the viscosity of the lubricant, and the problem is to suppress the occurrence of external surface defects such as indentation flaws and seizures associated with hot extrusion processing. However, the removal of the glass lubricant itself has not been studied.

  The present invention has been made in view of the new problem of glass lubricants in such a hot extrusion method for metal materials, and glass remaining on a workpiece and glass adhering to the inside of the container due to hot extrusion. The object of the present invention is to provide a glass lubricant for hot extrusion capable of improving the releasability of the glass and exhibiting excellent removal performance, as well as a method of hot extrusion of a metal material using the same and a method of manufacturing a metal tube. .

  In order to solve the above-mentioned problems, the inventors of the present invention performed a comparative study on removal performance using various glass lubricants during hot extrusion of a metal material. As a result, attention was paid to the fact that it is effective to improve the releasability by thermal shock by water cooling in order to exhibit excellent removal performance of the glass lubricant.

  In order to peel off the glass remaining on the workpiece and the glass adhering to the inside of the container from the surface of the metal material, the linear expansion coefficient α of the glass is greatly involved. That is, the linear expansion coefficient α is a rate at which the length changes in response to a change in temperature. However, the larger the difference between the glass and the metal material, the easier the glass peels from the surface of the metal material.

  Usually, the linear expansion coefficient α of glass is comparable or smaller than that of a metal material. For this reason, the peelability can be improved by selecting a glass having a small linear expansion coefficient α. In addition, by selecting an appropriate range for the viscosity of the glass, the lubricant is softened and melted in the temperature range of the extrusion process, and a sufficient amount of lubricant flows into the contact interface between the workpiece and the processing tool. And the lubricity can be improved.

  Therefore, during the hot extrusion of metal materials, the lubricity during hot extrusion is mainly governed by the viscosity of the glass, and the removal performance of the glass remaining on the workpiece after hot extrusion and the glass adhering to the inside of the container is And found that it is governed by the linear expansion coefficient α of the glass.

The present invention has been completed based on the above-described knowledge, and includes the following (1) to (3) glass lubricant for hot extrusion, and (4) to (6) a method for hot extrusion of a metal material. Is the gist.
(1) A glass lubricant for hot extrusion having a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less.
(2) A glass lubricant for hot extrusion used as a front lubricant and / or an inner surface lubricant of a metal material processed by hot extrusion, and has a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / And a viscosity at 1000 to 1250 ° C. is 10 ^2.5 to 10 ⁴ poise.
(3) A glass lubricant for hot extrusion used as an outer surface lubricant of a metal material processed by hot extrusion, having a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less, The glass lubricant for hot extrusion is characterized in that the viscosity at 1000 ° C. to 1250 ° C. is 10 ⁰ to 10 ^2.5 poise.

In the glass lubricant for hot extrusion according to the above (1) to (3) of the present invention, it is desirable to apply to a workpiece containing 20 mass% or more of Cr.
(4) A glass lubricant having a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less is used as at least one of a front lubricant, an outer lubricant and an inner lubricant of the metal material to be processed. This is a hot extrusion method for a metal material.
(5) The front surface of a metal material to be processed from glass having a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less and a viscosity at 1000 to 1250 ° C. of 10 ^2.5 to 10 ⁴ poise. A method for hot extrusion of a metal material, characterized by being used as a lubricant and / or an internal lubricant.
(6) A metal material to be processed with a glass lubricant having a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less and a viscosity at 1000 to 1250 ° C. of 10 ⁰ to 10 ^2.5 poise It is a hot extrusion method of a metal material characterized by being used as an outer surface lubricant.

  In the hot extrusion method for a metal material according to the above (4) to (6) of the present invention, it is desirable to target a workpiece containing 20% by mass or more of Cr. Moreover, it is desirable as a manufacturing method of a metal tube to perform a hot extrusion process by making a hollow billet into a workpiece by the glass lubrication process performed with the hot extrusion method of this invention.

  The “hot extrusion method of metal material” defined in the present invention has been described in the present specification based on the seamless Eugene Sejurne method, but is not limited to just a pipe material. It can be applied to hot extrusion of rods and molds. Similarly, the “metal tube” defined in the present invention is not limited to a seamless tube.

  According to the glass lubricant for hot extrusion of the present invention, by using it for hot extrusion of a metal material, it is possible to ensure lubricity at the time of hot extrusion, and by making the linear expansion coefficient α of the glass appropriate, The glass remaining on the workpiece after hot extrusion and the glass adhering to the inside of the container can be efficiently removed.

  According to the method for hot extrusion of a metal material and the method for manufacturing a metal tube of the present invention, by applying the glass lubricant for hot extrusion, glass adhesion to the surface of the workpiece after hot extrusion can be prevented. At the same time, glass adhesion to the inner surface of the container can be prevented. As a result, the deglass pickling process after hot extrusion can be simplified, the occurrence of surface roughening due to peracid washing is eliminated, and the outer surface defects of the workpiece caused by the glass adhering to the inside of the container are prevented. Can do.

The glass lubricant for hot extrusion of the present invention has a linear expansion coefficient α of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less. When the linear expansion coefficient α exceeds 80 × 10 ⁻⁷ (cm / cm / ° C.), the difference between the linear expansion coefficient α and the metal material becomes too small, and peeling due to thermal shock in water cooling after hot extrusion occurs. It becomes less and the peelability of the glass decreases.

A desirable linear expansion coefficient α in the present invention is 60 × 10 ⁻⁷ (cm / cm / ° C.) or less. Further, in the present invention, the lower limit of the linear expansion coefficient α is not specified, but usually glass having a linear expansion coefficient α of less than 40 × 10 ⁻⁷ (cm / cm / ° C.) is considered difficult to produce. This value can be the lower limit. However, the lower limit is not limited as long as a technique capable of easily and inexpensively producing a glass having a low linear expansion coefficient is established.
Moreover, although linear expansion coefficient (alpha) fluctuates with measurement temperature, in this invention, it prescribes | regulates as a value in normal temperature (25 degreeC).

  The glass lubricant for hot extrusion of the present invention adjusts the glass viscosity in addition to the above linear expansion coefficient α in order to ensure lubricity during hot extrusion. At this time, when the glass lubricant is used as the front lubricant, the outer lubricant, or the inner lubricant, it is necessary to adjust the glass viscosity according to the action of each lubricant.

  The front lubricant is made into a doughnut shape by adding a small amount of water glass or other binder to the powdered form and fitting it into a mold. Used as glass and set between heated workpiece and die. For this reason, the front lubricant softens and melts gradually due to the retained heat of the workpiece, and lubricates the die and the outer peripheral surface of the workpiece together with the glass powder of the outer lubricant applied to the outer peripheral surface of the workpiece. Acts as an agent.

  As the binder used for the front lubricant, Na-based, K-based and Li-based water glasses, borax, and the like can be used. In addition, when the remaining carbon content in the metal material is not a problem, an organic binder such as an aqueous vinyl acetate solution can also be used.

  The outer surface lubricant is used as glass powder. Usually, a heated workpiece is tumbled and transferred onto a table on which glass powder is spread to cover the outer surface. For this reason, the outer surface lubricant acts as a lubricant between the workpiece and the container inner surface and a lubricant between the die and the outer peripheral surface of the workpiece.

  The inner surface lubricant is used as glass powder and is put into an inner hole provided in a heated workpiece. For this reason, the inner surface lubricant is applied to the inner peripheral surface of the workpiece, and acts as a lubricant between the mandrel and the inner peripheral surface of the workpiece.

When the glass lubricant for hot extrusion of the present invention is used as a front lubricant and / or an inner surface lubricant, the linear expansion coefficient is 80 × 10 ⁻⁷ (cm / cm / ° C.) or less and 1000 Viscosity at from 10 to 1250 ° C. is 10 ^2.5 to 10 ⁴ poise.

That is, since the front lubricant and the inner lubricant are used for preventing seizure and reducing the friction coefficient, the viscosity is controlled at 10 ^2.5 to 10 ⁴ poise in the extrusion temperature range, thereby softening and melting the lubricant. And a sufficient amount of lubricant can be allowed to flow into the contact interface between the workpiece and the processing tool.

When used as an outer surface lubricant, the glass lubricant for hot extrusion of the present invention has a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less and a temperature of 1000 ° C. to 1250 ° C. The viscosity is 10 ⁰ to 10 ^2.5 poise.

That is, the external surface lubricant is controlled by controlling the viscosity at 10 ⁰ to 10 ^2.5 poise in the temperature range of the extrusion process in order to prevent the coated glass from falling off during handling after coating the surface of the workpiece. Adhesiveness to the workpiece surface can be improved.

  In the glass lubricant for hot extrusion of the present invention, the viscosity specified when used as a front lubricant, an outer lubricant and an inner lubricant is intended for the degree of processing in conventional hot extrusion. . For this reason, in the case of hot extrusion with a slight degree of processing, for example, hot pipe making using a hollow billet of carbon steel, in the case of hot extrusion with an extrusion degree of about 10%, the viscosity range specified above is set. Even if it comes off, it can be predicted that lubricity can be secured.

  The glass lubricant for hot extrusion of the present invention can employ a conventionally used glass lubricant supply method, and the outer surface lubricant and the inner surface lubricant are in powder form and are used in a heated workpiece. It can be coated directly or by rolling transfer. Further, the front lubricant is used by forming it into a donut shape using a binder to glass powder, and the shape that is commonly used can be used as it is.

  The particle size of the glass powder used in the present invention may be a conventional mesh size, and may be one pulverized to several μm to several hundred μm.

  Usually, the glass lubricant used for hot extrusion is prepared by mixing several glass powders having different compositions. Similarly, in the glass lubricant for hot extrusion of the present invention, two or more kinds of glass powders may be mixed and adjusted. The linear expansion coefficient α and the viscosity in that case are defined by the bulk performance of the mixture.

  The glass lubricant for hot extrusion of the present invention can be used for metal materials such as Ni-base alloys as well as carbon steel, Cr alloys, Cr-Ni alloys, etc., but contains 20% by mass or more of Cr. It is desirable to apply to Cr alloy, Cr-Ni alloy, Ni-base alloy and the like.

  These metal materials containing 20% by mass or more of Cr hardly generate oxide scale even when heated at a high temperature for hot extrusion. On the other hand, if it is a metal material which an oxide scale produces | generates, since glass can be peeled with the scale in the deglass processing after hot extrusion, it becomes comparatively easy to ensure peelability. Since such an effect cannot be expected with the metal material that is difficult to generate oxide scale, it is effective to apply a glass lubricant for hot extrusion having excellent peelability.

The method for hot extrusion of a metal material according to the present invention includes a glass lubricant having a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less, a front lubricant, an outer lubricant and a metal material to be processed. It is characterized by being used as at least one of internal lubricants. A difference in the linear expansion coefficient α with the metal material can be secured, and the releasability of the glass remaining on the workpiece after hot extrusion and the glass adhering to the inside of the container can be improved.

The method of hot extrusion of a metal material of the present invention is a glass having a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less and a viscosity at 1000 to 1250 ° C. of 10 ^2.5 to 10 ⁴ poise. Is used as a front lubricant and / or an internal lubricant of the metal material to be processed. The lubrication performance of the front lubricant and the inner lubricant used for preventing seizure and reducing the friction coefficient can be exhibited, and the peelability after hot extrusion can be improved.

The method for hot extrusion of a metal material of the present invention is a glass having a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less and a viscosity at 1000 to 1250 ° C. of 10 ⁰ to 10 ^2.5 poise. The lubricant is used as an outer surface lubricant of a metal material to be processed. It is possible to prevent the glass from dropping off due to the handling of the workpiece during hot extrusion, to improve the adhesion to the surface of the workpiece, and to improve the peelability after hot extrusion.

In the metal tube manufacturing method of the present invention, a glass lubricant having a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less is used as at least one of a front lubricant, an outer lubricant and an inner lubricant. Further, glass having a viscosity in the processing temperature range of 10 ^2.5 to 10 ⁴ poise is used as a front lubricant and / or an internal lubricant, and in addition, a glass lubricant having a viscosity in the processing temperature range of 10 ⁰ to 10 ^2.5 poise. Hot extrusion is performed using a hollow billet that has been subjected to glass lubrication treatment as a work material.

  By applying the metal pipe manufacturing method of the present invention, the deglass pickling process after hot extrusion can be simplified in the production of seamless pipes, the occurrence of surface roughening due to peroxidation is eliminated, and the inside of the container is further improved. Since the outer surface defect of the workpiece caused by the adhering glass can be prevented, an optimum hot extrusion pipe making method by the Eugene Sejurune method is obtained.

Example 1
Six types of glass lubricants A to F (particle size: about 180 μm) having the composition shown in Table 1 were prepared, and the peelability was investigated. A block-shaped test piece (20 mm × 20 mm × 20 mm) of a steel type SUS316 was prepared, and 2 g of each glass powder was coated on the test surface, and the block was heated for 1 hour at 1250 ° C. in a heating furnace in an air atmosphere. The test piece was taken out and immediately immersed in a water bath and rapidly cooled.

  The test surface of the obtained block-shaped test piece was observed, the ratio of the area where the glass peeled to the entire test surface was measured as the peeled area ratio, and the measurement results are shown in Table 1. Here, the case where the peel area ratio was 80% or more was evaluated as good peelability. The linear expansion coefficient α of the glass lubricant was measured with a commercially available thermomechanical analyzer (TMA).

From the measurement results shown in Table 1, in glass lubricants A, B, C and D having a linear expansion coefficient α of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less, the peel area ratio exceeds 80%. It can be seen that the peelability is good.

In particular, in the glass lubricants A and B having a linear expansion coefficient α of 60 × 10 ⁻⁷ (cm / cm / ° C.) or less, the peeled area ratio exceeded 90%, and showed remarkable peelability.
(Example 2)
A seamless pipe was manufactured by the hot extrusion pipe manufacturing method shown in FIG. 1 using the steel type SUS316 as a workpiece. The used glass lubricants are six types of lubricants G to L having the main composition shown in Table 2, and the manufactured inner and outer surface states of the seamless pipe and the state of glass adhesion, and the state of glass adhesion on the inner surface of the extruded container. investigated. The viscosity of the glass lubricant was measured by a platinum pulling method. Moreover, the linear expansion coefficient (alpha) of glass was measured with the commercially available thermomechanical analyzer (TMA).

  When used as a front lubricant, the glass lubricant was molded into a disk shape using commercially available water glass No. 3. In addition, when used as an inner surface lubricant or an outer surface lubricant, it was applied as a powder. The particle size of the glass powder used here was about 180 μm.

  At the time of hot extrusion, a hollow billet having an outer diameter of 174 mm, an inner diameter of 44 mm, and a length of 800 mm as a workpiece and a 20R processed tip was used, and the heating temperature was 1250 ° C. The dimensions of the manufactured seamless tube were an outer diameter of 47 mm, an inner diameter of 41 mm, a wall thickness of 3 mm, and a length of 40 m.

  The obtained seamless pipe was cut into three, and water was sprayed on the cooling floor by a shower method, and the pipe was cooled to room temperature. Thereafter, the tube surface conditions such as glass peeling on the tube surface and occurrence of defects were observed. Moreover, water discharge was carried out to the container inner surface for every hot extrusion process, and when the glass lubricant adhering to the container inner surface was removed with a metal brush, the glass adhesion state on the container inner surface was observed. These observation results are shown in Table 3.

  Evaluation of the glass peeling condition shown in Table 3 is as follows: ◎: Completely peeled, ○: Almost peeled (remaining area less than 3%), Δ: Part of the glass not peeled (remaining area less than 3-10%) X: The area where the glass is not peeled is present in a wide range (remaining area is 10% or more).

  Similarly, the evaluation of the pipe surface state is as follows: ◎: Good, ○: Gloss due to insufficient lubrication or surface roughness increase due to excessive lubrication, but no problem, ×: Image due to seizure due to insufficient lubrication, or excessive lubrication It is shown by the classification that the skin can be seen.

As shown in Table 3, test No. 1 using a glass lubricant outside the range defined in the present invention as an internal lubricant. 1 and test no. In No. 2, there was a portion where the glass was not partially peeled on the inner peripheral surface of the tube after hot extrusion. 1, test no. 2 outer peripheral surface and test no. Nos. 3 to 5 show that no glass remains on the tube surface after hot extrusion, and the peelability is good. In addition, Test No. No surface defects such as image sticking and elephant skin occurred in 1-5.

  On the other hand, as a comparative example, test No. using a glass lubricant not specified in the present invention was used. In Nos. 6 to 8, in the glass peeling situation, the area where the surface of the tube was less than 10% on the outer peripheral surface and the inner peripheral surface of the tube but the glass adhered was confirmed. In addition, Test No. In 7-8, surface defects, such as image sticking and elephant skin, occurred in the tube surface state.

Further, in the observation of the inner surface of the container, the test No. using the glass lubricant defined in the present invention was used. In Nos. 1 to 5, glass was not adhered, but test No. In 6 to 8, many portions where the glass remained were observed.
(Example 3)
Using a Cr—Ni alloy (mass%, Cr: 25%, Ni: 35% and Fe: 40%) as a work material and applying the hot extrusion pipe making method shown in FIG. Manufactured. As in Example 2, the glass lubricants used were six types of lubricants G to L having the main compositions shown in Table 2, and the inner and outer surface states of the tubes and the state of glass adhesion, as well as the glass on the inner surface of the extrusion container. The adhesion situation was investigated. The molding method of the front lubricant, the coating method of the inner surface lubricant and the outer surface lubricant, and the particle size of the glass powder used were the same as in Example 2.

  In the hot extrusion of the Cr—Ni alloy, a hollow billet having an outer diameter of 330 mm × an inner diameter of 206 mm × a length of 1100 mm was used as a workpiece, and the heating temperature was 1250 ° C. The manufactured extruded tube had dimensions of an outer diameter of 223 mm, an inner diameter of 195 mm, a wall thickness of 14 mm, and a length of 5.3 m.

  The obtained pipe | tube was cut | disconnected into three similarly to the case of Example 2, and water was sprayed by the shower system in the cooling bed, and the pipe | tube was cooled to normal temperature. Thereafter, the tube surface conditions such as glass peeling on the tube surface and occurrence of defects were observed. Moreover, water discharge was carried out to the container inner surface for every hot extrusion process, and when the glass lubricant adhering to the container inner surface was removed with a metal brush, the glass adhesion state on the container inner surface was observed. These observation results are shown in Table 4.

  The evaluation of the glass peeling state and the evaluation of the tube surface state shown in Table 4 were the same as the evaluation shown in Table 3 of Example 2.

  As shown in Table 4, test Nos. Using a glass lubricant outside the range specified in the present invention as an inner surface lubricant. 9 and test no. In No. 10, there was a portion where the glass was not partially peeled on the inner peripheral surface of the tube after hot extrusion. 9, test no. No. 10 outer peripheral surface and test no. In any of 11 to 13, it can be seen that no glass remains on the tube surface after hot extrusion, and the peelability is good. In addition, Test No. No surface defects such as image sticking and elephant skin occurred in 1-5.

  On the other hand, as a comparative example, test No. using a glass lubricant not specified in the present invention was used. In Nos. 14 to 16, it was confirmed that 10% or more of glass adhered to the outer peripheral surface and inner peripheral surface of the tube in the area of the tube surface in the glass peeling state. In addition, Test No. In 15-16, surface defects, such as image sticking and elephant skin, occurred in the tube surface state.

  Further, in the observation of the inner surface of the container, the test No. using the glass lubricant defined in the present invention was used. In Nos. 9 to 13, the glass was not adhered, but the test No. In 14 to 16, many portions where the glass remained were observed.

  According to the glass lubricant for hot extrusion of the present invention, by using it for hot extrusion of a metal material, it is possible to ensure lubricity at the time of hot extrusion, and by making the linear expansion coefficient α of the glass appropriate, The glass remaining on the workpiece after hot extrusion and the glass adhering to the inside of the container can be efficiently removed.

  According to the method for hot extrusion of a metal material and the method for manufacturing a metal tube of the present invention, by applying the glass lubricant for hot extrusion, glass adhesion to the surface of the workpiece after hot extrusion can be prevented. At the same time, glass adhesion to the inner surface of the container can be prevented. As a result, the deglass pickling process after hot extrusion can be simplified, the occurrence of surface roughening due to peracid washing is eliminated, and the outer surface defects of the workpiece caused by the glass adhering to the inside of the container are prevented. Therefore, it can be widely applied as a hot working method.

It is sectional drawing explaining the hot extrusion pipe making method used for manufacture of a seamless pipe.

Explanation of symbols

1: glass disk, front lubricant, 2: die 3: mandrel, 4: die holder 5: die backer, 6: container 7: dummy block, 8: billet, hollow billet

Claims (9)

A glass lubricant for hot extrusion, which has a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less. A glass lubricant for hot extrusion used as a front lubricant and / or an internal lubricant of a metal material processed by hot extrusion,
Glass lubricant for hot extrusion having a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less and a viscosity at 1000 to 1250 ° C. of 10 ^2.5 to 10 ⁴ poise . A glass lubricant for hot extrusion used as an outer surface lubricant of a metal material processed by hot extrusion,
Glass lubricant for hot extrusion having a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less and a viscosity at 1000 to 1250 ° C. of 10 ⁰ to 10 ^2.5 poise .   The glass lubricant for hot extrusion according to any one of claims 1 to 3, wherein the metal material is a workpiece containing 20 mass% or more of Cr. A glass lubricant having a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less is used as at least one of a front lubricant, an outer lubricant and an inner lubricant of a metal material to be processed. A hot extrusion method for metal materials. A glass material having a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less and a viscosity at 1000 ° C. to 1250 ° C. of 10 ^2.5 to 10 ⁴ poises, a front lubricant of a metal material to be processed, and A method for hot extrusion of a metal material, which is used as an internal lubricant. A glass lubricant having a linear expansion coefficient of 80 × 10 ⁻⁷ (cm / cm / ° C.) or less and a viscosity at 1000 to 1250 ° C. of 10 ⁰ to 10 ^2.5 poise is used to lubricate the outer surface of the metal material to be processed. A method for hot extrusion of a metal material, characterized by being used as an agent.   The method for hot extrusion of a metal material according to any one of claims 5 to 7, wherein the metal material is a workpiece containing 20 mass% or more of Cr.   A method for producing a metal tube, wherein hot extrusion is performed using the hollow billet subjected to the glass lubrication treatment according to claim 5 as a workpiece.

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