JP2001239364A - Hot working method for, austenitic stainless steel containing b - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot working method for an austenitic stainless steel plate containing B which causes no welding crack when a high efficient overlaying welding is performed and which can be free from edge cracking of rolled materials during hot working. SOLUTION: When an austenitic stainless steel plate containing 0.3 to 2.5, by weight percent of B is hot worked, the invention relates to the hot working method for an austenitic stainless steel containing B which is hot worked by locating an overlaying welding film layer having 3 mm or more wall thickness on the side of the steel plate that consists of stainless steel having Ni: not more than 4% and B: 0.1-0.4% in weight percent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot working method for B-containing austenitic stainless steel used as a neutron shielding material for nuclear-related equipment such as containers for transporting nuclear fuel, used nuclear fuel storage racks, and the like.

[0002]

2. Description of the Related Art Utilizing the excellent thermal neutron absorption of B, austenitic stainless steel to which B is added is used as a thermal neutron controlling material and a blocking material, as a nuclear fuel transport container,
Used for spent nuclear fuel storage racks. In general,
Spent nuclear fuel used at a nuclear power plant is stored in a pool at the power plant until it is processed at a reprocessing plant. Due to the need to store as much spent nuclear fuel as possible in a limited site, the amount of B added to the B-containing austenitic stainless steel tends to increase and the plate thickness to decrease.

[0003] The amount of B dissolved in austenite is very small, and most of the added B precipitates as a boron containing Fe and Cr. Although the hot workability and the corrosion resistance deteriorate due to the presence of the boron, the tendency becomes remarkable as the B content increases.

Generally, in hot working such as forging and rolling of a B-containing austenitic stainless steel, the slab is heated by a heating furnace and working such as forging and rolling is repeated to prevent the temperature of the workpiece from lowering. This is performed while ensuring hot workability. Since the hot workability is inferior as the B content is higher, the heating-
The number of processing repetitions increases. Therefore, an increase in the B content and a thinning of the steel result in an increase in manufacturing cost.

In order to solve the above problems, various studies have been made so far. Japanese Patent Application Laid-Open No. 61-201726 discloses that a B-containing stainless steel ingot is directly or after being shaped into a rectangular shape, and at least four main surfaces of the steel ingot are tightly surrounded by an iron tube, and then compacted by slab rolling or forging. A method of hot rolling after the rolling is disclosed.

In Japanese Patent Application Laid-Open No. 63-220904, a B-containing austenitic stainless steel as a base material is packed with a steel material having a smaller deformation resistance and then packed in a 110
Heat at 0 ° C or higher and 1175 ° C or lower, T (° C) = 53 × B
A method of finish rolling at a temperature of (mass%) + 870 or more is disclosed.

[0007] Although these methods can prevent ear cracks, it is difficult to secure the required thickness accuracy, and also requires the work of wrapping the pack material and the dismantling work after rolling, which increases the manufacturing cost. Problem.

As a method for avoiding problems of plate thickness accuracy, wrapping of a pack material and dismantling work, Japanese Patent Laid-Open No.
Japanese Patent No. 3506 discloses that a side surface of a B-containing austenitic stainless steel material as a base material is rolled by welding and rolling a steel material having a smaller deformation resistance than the base material as a frame material, thereby preventing occurrence of edge cracks. A hot rolling method is disclosed. In this method, it is necessary to prepare a frame material having a high-precision groove shape and weld it so as not to peel off during hot working. Therefore, the thickness of the normally cast ingot (steel ingot) or forged slab is 80 mm.
Because of the above, it is difficult to apply them to hot working.

In addition, JP-A-1-195243 and JP-A-5-263133 disclose the purpose of preventing edge cracking by regulating the rolling reduction per heat, the lower limit temperature, and the like, and repeating the heating-rolling. The B of a predetermined thickness
A method for obtaining a steel containing austenitic stainless steel is disclosed. These methods also have a problem of cost increase due to an increase in the number of heats, and are also difficult to apply to a high-productivity tandem rolling mill in which reheating is mechanically impossible.

[0010] Further, a method is known in which a metal material having good hot workability is overlay-welded to the side surface of a steel slab and rolled.
According to this method, there is an advantage that the weld overlay can be relatively easily removed by a trimmer or the like after rolling. However, in this overlay welding method, in a highly efficient welding method such as MAG and SAW, the amount of oxygen in the weld metal increases, and welding cracks are likely to occur. When a weld crack occurs, it may be a starting point and lead to the occurrence of an ear crack, and the ear crack cannot be completely prevented.

In particular, for overlay welding on the side surface of a material to be rolled having a large area, unless a highly efficient welding method such as MAG or SAW is employed as compared with TIG or the like, the welding operation cost cannot be reduced.

[0012]

The object of the present invention is to provide a high B
It is an object of the present invention to provide a hot working method capable of working a contained austenitic stainless steel without reheating during hot working and without generating edge cracks up to a predetermined plate thickness. More specifically, even if overlay welding is performed on the side surfaces of the billet by a high-efficiency welding method, there is no occurrence of welding cracks, and the occurrence of edge cracks in the material to be rolled during hot working is to be prevented. An object of the present invention is to provide a hot working method for a high-B content austenitic stainless steel slab that can be performed.

[0013]

Means for Solving the Problems The present invention provides the following (1) to
The gist of the present invention is a hot working method of (3) B-containing austenitic stainless steel.

(1) When hot working an austenitic stainless steel slab containing 0.3 to 2.5% by mass of B, Ni: 4% or less by mass% on the side surface of the slab, B:
B which is provided with a build-up welding coating layer having a thickness of 3 mm or more made of stainless steel containing 0.1 to 0.4% and hot-worked B
Hot-working method for austenitic stainless steels containing steel.

(2) When hot working an austenitic stainless steel slab containing 0.3 to 2.5% by mass of B, Ni: 4% or less by mass% on the side surface of the slab, B:
A hot working method for a B-containing austenitic stainless steel, in which a build-up welding coating layer having a thickness of 3 mm or more made of stainless steel containing 0.4% or less and Ti: 0.01 to 2% is provided and hot-worked.

(3) The overlay welding coating layer further comprises
(2) The hot working method for B-containing austenitic stainless steel according to (2), which is a build-up weld coating layer of stainless steel containing Al: 0.003 to 0.4%.

Here, the slab refers to a continuously cast slab, a bulk cast slab, a bulk rolled slab, and a cast ingot (steel ingot).

The present inventors have adopted a method of providing a build-up weld coating layer on the side surface of a material to be rolled, which is more economical than a method of packing a slab, and using a metal material suitable for build-up weld coating. As a result of conducting various tests for development, the following findings were obtained.

A) The weld cracking susceptibility and hot workability of the overlay welding coating layer are affected by the contents of Ni and B in the overlay welding coating layer. B) Ti, When Al is contained, the effect of preventing welding cracks and the effect of preventing ear cracks become more remarkable.

Hereinafter, a description will be given of a test which led to the above finding.

(Test 1) In selecting a welding coating material which does not cause welding cracks and is effective in preventing ear cracks, first, the present invention was mainly studied.

As the material to be rolled, a lump-cast slab of austenitic stainless steel having a width of 140 mm, a thickness of 80 mm, and a length of 200 mm containing 1% by mass of B was used. As the welding coating material, SUS308L of austenitic stainless steel and SU of ferritic stainless steel were used.
S436L, two-phase (austenite-ferrite) stainless steel SUS329J4L and high-purity Fe, 5 m by TIG two-layer welding on the entire side surface of one side of the slab
An m-thick overlay coating was provided. The opposite side edge was solid.

The welding conditions were as follows: current: 160 A, voltage: 17
V, welding speed: 10 cm / min. After build-up welding,
When the presence or absence of welding cracks was confirmed by a penetrant inspection test of the cross section, cracks were found in SUS329J4L and high-purity Fe, but no cracks were found in SUS308L and SUS436L.

The slab welded in the above manner was rolled using a reverse hot rolling mill having a work roll diameter of 450 mm. The heating temperature of the slab was 1180 ° C. to avoid melt embrittlement. The pass schedule was as follows.

80 → 60 → 45 → 35 → 28 → 21 → 1
6 → 12 → 9 → 7 → 5 → 4 (mm) The rolling was carried out while visually checking the state of the ear cracks, and the rolling was stopped at the pass where the ear cracks occurred on both sides. As for the solid side,
Ear cracks were observed at the seventh pass when the surface area of the material to be rolled increased and the temperature decreased greatly.

On the side of the overlaid coating, when the coating material was SUS329J4L and high-purity Fe, ear cracks were generated at the eighth pass, and with high-purity Fe, ear cracks of about 5 mm were observed. It has been found that even in a material such as high-purity Fe having a smaller deformation resistance than a B-containing austenitic stainless steel, the effect of preventing ear cracks cannot be sufficiently obtained when welding cracks are present. On the other hand, if the coating material is SU
In the case of S308L and SUS436L, no ear cracks were observed even after 11 passes, which proved to be a weld coating material effective for preventing ear cracks.

(Test 2) Based on the results of Test 1, a more detailed study was conducted mainly on a Cr-containing stainless steel centering on SUS308L and SUS436L as welding coating materials. Since the amounts of Ni and B in the cladding layer change depending on the dilution ratio during welding, the chemical composition of the cladding layer is considered important for preventing welding cracks and edge cracks. did.

As the material, a lump-forged austenitic stainless steel slab having a thickness of 150 mm, a width of 150 mm, and a length of 150 mm with various B contents was used. Overlay welding was performed on the side surfaces of the slab with welding materials having different compositions to evaluate weld cracking and hot workability. In addition, the Cr amount of the raw material and the welding material was set to 19 to 20% by mass. (Hereinafter, all chemical composition percentages are expressed as mass%.) The welding method is MAG welding, which is more efficient than TIG, and the current is 220 A, the voltage is 25 V, and the welding speed is 15 cm / min. Was welded to a thickness of 10 to 15 mm.

[0029] Weld cracks were evaluated by penetrating deep flaws in the cross section. A hot tensile test was used for evaluation of hot workability. A test piece having a diameter of 10 mm and a length of 130 mm was cut out from the weld metal portion, heated to 1150 ° C, cooled at a rate of 100 ° C / min, and subjected to a tensile test at 900 ° C. The strain rate in the tensile test was set to 1 / S, and the specimen was rapidly cooled immediately after the test to determine the drawing (cross-sectional shrinkage, unit%) of the test piece.

FIG. 1 is a graph showing the correlation between the amounts of Ni and B in the build-up weld metal obtained by the analysis and the slab restrained weld cracking. From FIG. 1, it can be seen that the occurrence of welding cracks depends on the amounts of Ni and B, and exhibits excellent weld cracking resistance when in a certain range.

FIG. 2 shows the correlation between the Ni content and the B content of the overlay weld metal and the reduction in the results of the high temperature tensile test. From FIG. 2, it can be seen that the build-up weld coating layer in the range of Ni: 4% or less and B: 0.4% or less has a drawn at 900 ° C. of 60% or more, and shows excellent hot workability.

(Test 3) Based on the results of Test 2, an evaluation test for ear cracks caused by hot rolling was performed. As a material to be rolled, a width of 140 mm, a thickness of 80 mm, and a length of 200 containing 1% of B
A forged slab of austenitic stainless steel with a diameter of 0.2 mm was used. SUS430 steel and SUS436L steel, which are ferritic stainless steels, were used as welding materials, and overlay welding was performed on the entire surface on one side of the slab while changing the dilution ratio. The welding method and conditions were the same as in Test 2, and the thickness of the overlay welding coating layer was 3 mm. The opposite side was solid.

The weld section was evaluated for weld cracking by a penetrant inspection test, and no crack was observed in any case.

The slab thus welded was subjected to hot rolling under the same conditions as in Test 1. As in Test 1, rolling was performed while visually confirming the state of ear cracks, and rolling was stopped at a path where ear cracks occurred on both sides.

Regarding the solid side, as in Test 1,
Ear cracks were observed at the seventh pass when the surface area of the material to be rolled increased and the temperature decreased greatly. The larger the dilution ratio, that is, the larger the amount of Ni and B in the build-up weld metal, the smaller the number of passes, the more cracks occurred. Ear cracking occurred in the same 7th pass as solid wood
The amounts of Ni and B exceeded 4% and 0.4%, and the effect of preventing ear cracks was not obtained.

When the build-up weld metal is Ni: 4% or less, B: 0% or less.
If it is less than 4%, ear cracks are observed after 9 passes,
Ear crack preventing effect was obtained. On the other hand, SUS containing Ti
436L steel is used as welding material,
When i: 4% or less and B: 0.4% or less, generation of edge cracks was not observed even after 11-pass rolling, and an excellent edge crack prevention effect was obtained.

Therefore, a ferritic stainless steel in which the Ti content was further changed widely was used as a welding material, and as in the above-mentioned manner, edge cracks were evaluated by hot-rolling by overlay welding on the slab side surfaces. Then, when Ti was contained in the range of 0.01 to 2%, a good effect of preventing ear cracks and welding cracks was obtained. In particular, these effects were remarkable when they were in the range of 0.03 to 1%. When the amount of B contained in the build-up weld metal layer is less than 0.1%, welding cracks tend to occur easily, but when Ti is contained, welding cracks do not particularly occur. This is considered to be due to the fact that the build-up welded structure was very fine, and thereby a good edge crack preventing effect was obtained. Upon closer observation,
Generation of Ti nitride and Ti boride was observed, and it was presumed that these formed nuclei to form a fine solidified structure.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION B-containing austenitic stainless steel slab: The amount of B in austenitic stainless steel as a material to be hot worked is set to 0.3 to 2.5%. If it is less than 0.3%, the thermal neutron absorption capacity is not sufficient. Although the thermal neutron absorption ability increases with an increase in the amount of B added, if it exceeds 2.5%, the ductility and toughness at room temperature deteriorate significantly. Therefore, the B content is set to 0.3 to 2.5%.

The element other than B in the B-containing austenitic stainless steel of the present invention is C: 0.0
8% or less, Si: 1% or less, Mn: 2% or less, P: 0.04
%, S: 0.01% or less, Cr: 16 to 25%, Ni:
It is preferred to be 7 to 15%. Also, if necessary
It is preferable to contain Mo: 1.5% or less, Cu: 0.5% or less, and Al: 0.3% or less singly or in combination. From the viewpoint of ensuring sufficient weldability, N: 0.05%
It is preferable to set the following.

The stainless steel slab refers to a continuously cast slab, a forged slab, a slab rolled slab, and a cast ingot (steel ingot) as described above. These slabs are generally rectangular parallelepipeds, and are subjected to hot working such as hot rolling or forging so as to extend in the longitudinal direction. The side surface of the steel slab is a surface other than the processing surface (in the case of rolling, the surface that comes into contact with the roll), and usually, a build-up welding coating layer may be provided on the entire two side surfaces in the longitudinal direction. In some cases, the corners of the steel slab are chamfered. In this case, the overlaid weld coating layer may be provided so as to extend around the corners and the machined surface.

Build-up weld coat: The build-up weld coat layer is N
i: stainless steel containing 4% or less and B: 0.1 to 0.4%. In addition, if necessary, Ti: 0.01 to 2%,
When Al is contained in an amount of 0.003 to 0.4%, the B content can be set to 0.4% or less (including 0.1% or less).

If the Ni content exceeds 4% and the B content exceeds 0.4%, the hot workability is not sufficient. Ni: 4% or less, B: 0.4%
Even in the following ranges, when B is not 0.1% or more, the susceptibility to solidification cracking during build-up welding increases, and welding cracks are likely to occur. In addition, Ti: 0.01 to 2% is contained, or Al: 0.003 to
In the case where 0.4% is contained, even if B is less than 0.1%, no welding crack occurs.

In order to keep the Ni and B contents in the build-up weld coating layer within the above ranges, it is necessary to adjust the welding materials and welding conditions. That is, it is preferable to use a ferritic stainless steel having a Ni content of 3% or less and a B content of 0.3% or less as a welding material. When using a ferritic stainless steel having a Ni content of 3% or less without containing B, for example, in SAW (including band arc welding),
The amounts of Ni and B in the build-up weld coating layer may be controlled using a flux containing B. Also, MA
In the case of G, the amounts of Ni and B in the build-up welding coating layer may be controlled by using a flux-cored wire containing these alloy elements in the welding material. The same applies to the case of a covered arc welding rod.

It is also preferable to reduce the amount of heat during the overlay welding to minimize the dissolution of the B-containing stainless steel into the overlay welding layer during hot working.

In order to impart good weld crack resistance and hot workability to the build-up welded layer, at least 0.01% or more is required.
It is preferable to contain Ti. On the other hand, if it exceeds 2%,
In order to saturate the effect of preventing ear cracks and adversely affect the weldability and toughness, if it is contained, 0.01 to 2%
And On the other hand, if it exceeds 1%, the effect of preventing welding cracks is saturated. Therefore, the amount of Ti is preferably set to 0.01 to 1%. In order to obtain a remarkable edge crack prevention effect and a weld cracking effect, the Ti content is preferably set to 0.03 to 0.5%.

Al is contained as necessary as a deoxidizing element because it effectively acts to refine the solidified structure by Ti. In order to obtain the effect, it is necessary to contain at least 0.003% or more. If the content exceeds 0.4%, the toughness is adversely affected.
Preferably it is 0.4%. More preferably, 0.
01 to 0.2%.

When Ti and Al are contained in the build-up weld coating layer, a sufficient weld crack preventing effect can be obtained even if B of the build-up weld coating layer is less than 0.1%.

The reason why the build-up welding coating layer is limited to stainless steel is to secure the amount of ferrite in the weld metal and to provide the same oxidation resistance and corrosion resistance as the B-containing austenitic stainless steel as the material. is there. For this reason, steel containing a Cr content of 12% or more is generally referred to as stainless steel.
It is preferably at least 6% and at most 25%, more preferably at least 18%.

When the build-up weld coating layer has the above amount of Ni,
The object of the present invention is achieved by using stainless steel containing B and, if necessary, Ti and Al. However, other elements may be contained in the build-up weld coating layer. Hereinafter, the elements that may be contained in the build-up weld coating layer and their contents will be described.

C: From the viewpoint of corrosion resistance, the content is preferably 0.06% or less.

N: From the viewpoint of weldability, the content is preferably 0.06% or less.

Si, Mn: Si and Mn are added for deoxidation.
It is preferable that both elements are 2% or less.

P, S: P and S are elements that impair the properties of steel. It is preferably 0.1% or less and 0.03% or less, respectively.

Mo: It is preferable to add Mo as needed in order to enhance corrosion resistance. It is preferable that the addition amount be 1.5% or less.

Nb, V: Can be added as needed to enhance corrosion resistance. It is preferable that the addition amount is 1% or less.

O: O in the build-up weld coating layer inevitably increases as compared to the weld metal material. O has the effect of impairing the toughness, so it is preferable to control it to 0.2% or less.

The metal structure of the overlay welding coating layer is preferably a ferrite structure or a structure composed of ferrite and austenite. In the case of a structure composed of ferrite and austenite, the austenite phase is 50%.
% Is preferable.

The smaller the crystal grain size of the overlay welding coating layer, the better. Specifically, the crystal grain size is preferably 0.5 mm or less. By setting B, Ti, and Al within the range of the present invention, the crystal grain size can be easily reduced to 0.5 mm or less.

TIG, MA
G, SAW (including band arc welding) etc. are applied,
These can be used in combination as needed. MA
Since G and SAW have good welding efficiency, these welding methods are recommended.

The thickness of the coating layer is set to 3 mm or more in consideration of not only the prevention of edge cracks but also the welding workability. When the thickness is increased, the effect of preventing ear cracks becomes more certain, so that the coating thickness is preferably 5 mm or more. On the other hand, an excessively thick coating is not preferable because the welding operation cost increases. The coating thickness is preferably set to 50 mm or less. The coating thickness is more preferably 40 mm or less, and most preferably 15 mm or less.

Hot working: Hot working refers to slab forging, thick plate rolling, hot rolling steel strip rolling and the like. The heating temperature of the billet is set to a high temperature within a range that does not cause melt embrittlement. In the case of B-containing austenitic stainless steel, 1100 to 120
The temperature is preferably set to 0 ° C. It is preferable that the finishing temperature in hot forging or hot rolling be high to prevent edge cracks. However, as long as the hot deformability of the welding cladding permits, 60
A low temperature finish of 0 to 900 ° C. is also possible.

[0062]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, stainless steel having the chemical composition shown in Table 1 is melted, and each steel piece of a continuous cast slab, a slab forged slab, a slab rolled slab, and a steel ingot (ingot) is forged and hot worked. And

[0063]

[Table 1] The thickness of each slab is as shown in Table 2, and the lengths are all 2
000 mm.

[0064]

[Table 2] A ferritic stainless steel welding material having a chemical composition shown in Table 3 was welded on the side surface in the longitudinal direction of each billet by MAG or SAW under the conditions shown in Table 4. Table 2 shows the results obtained by analyzing the contents of Ni, B, Ti and Al in each overlay welding layer.

[0065]

[Table 3]

[Table 4] Next, the steel slab provided with the build-up coating layer was processed to a finished plate thickness shown in Table 2 without reheating by hot rolling or hot forging to obtain a steel plate. As shown in Table 2, 6,
8, 9, 11 to 15 and 17 were overlaid with SAW, except for 16 which was not overlaid,
Overlay welding was performed with MAG. In addition, No. 4, 5, 1
Plates 0, 11, 18 and 19 were subjected to thick plate rolling, and the others were subjected to hot rolled steel strip rolling. The heating temperature in hot rolling or hot forging was 1150 ° C.

When the welding material is a or b in the overlay welding by SAW, the flux containing B, Ti, and Al is used to form B, Ti, and Al of the overlay welding coating layer.
The content was adjusted. Specifically, No. In 9, B, Ti,
Flux containing all of Al. B at 11 and 12
Flux containing No. In No. 15, a flux containing Ti and Al was used. In addition, No. In No. 17, a flux containing no B, Ti, or Al is used.

The weld cracks were evaluated by penetrating the cross section for flaw detection. After hot working, the presence or absence of ear cracks was visually observed.

As is clear from Table 2, when the Ni and B contents of the build-up welding coating layer are 4% or less and 0.1 to 0.4%, respectively, a good steel sheet without edge cracks can be obtained. Was. Also,
Even when the B content f was less than 0.1%, when the overlay welding coating layer contained Ti or Al in addition to Ti, a good steel sheet without edge cracks was obtained.

Further, the overlay welding coating layer containing Ti (Nos. 1-4, 6-9, 13-15) and those not containing Ti (Nos. 5, 10-12) were used. In comparison, when the Ti content was 0.01% to 2%, no ear cracking was observed even when the rolling reduction (working rate) was increased, as compared with the case where Ti was not included. Furthermore, among the cladding weld coating layers containing Ti, those containing Al (Nos. 8, 9, 13, and 15) do not contain Al (Nos. 1 to 4). , 6, 7, 14), the occurrence of ear cracks was not observed even when the rolling reduction (working degree) was further increased.

On the other hand, no. No. 16, the chemical composition of the build-up weld coating layer was out of the range specified in the present invention. Nos. 17, 18 and No. 17 having a small build-up weld coating thickness. In No. 19, ear cracks occurred and a steel sheet of good quality could not be obtained.

[0071]

According to the hot working method of the present invention, a high B-containing austenitic stainless steel slab, which is a difficult-to-work material, is not cracked even if it is not reheated during hot working and industrially. Processing can be performed stably with good yield. Therefore, it is possible to supply a steel sheet having excellent characteristics relatively inexpensively to the needs of neutron shielding materials for nuclear-related equipment, such as containers for transporting nuclear fuel and spent nuclear fuel storage racks, which have been increasing in recent years.

[Brief description of the drawings]

FIG. 1 is a diagram showing a correlation between Ni and B contents and slab restrained weld cracking.

FIG. 2 is a diagram showing a correlation between drawing and Ni and B contents in a high-temperature tensile test result.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C22C 38/00 302 C22C 38/54 38/54 B23K 103: 04 B23K 103: 04 G21C 19/06 B (72) Inventor Kazuhiro Ogawa 4-5-33 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Inside Sumitomo Metal Industries, Ltd. (72) Inventor Shinji Tsuge 4-5-33, Kitahama, Chuo-ku, Osaka City, Osaka Sumitomo Metal Industries In-company (72) Inventor Yoshiaki Noguchi 1-117 Fuso-cho, Amagasaki-shi, Hyogo Sumikin Welding Co., Ltd. (72) Inventor Akihiko Shibata 1-17 Fuso-cho, Amagasaki-shi, Hyogo Sumikin Welding Co., Ltd.

Claims (3)

[Claims] When hot-working an austenitic stainless steel slab containing 0.3 to 2.5% by mass of B, Ni: 4% or less, B: 0. 1 to
A hot working method for a B-containing austenitic stainless steel, comprising providing a build-up weld coating layer having a thickness of 3 mm or more and made of stainless steel containing 0.4%. 2. When hot working an austenitic stainless steel slab containing 0.3 to 2.5% by mass of B, Ni: 4% or less by mass% and B: 0. Hot working of a B-containing austenitic stainless steel characterized in that a build-up welding coating layer of a thickness of 3 mm or more made of stainless steel containing 4% or less and Ti: 0.01 to 2% is provided and hot-worked. Processing method. 3. The cladding weld coating layer further comprises Al:
The hot-working method for a B-containing austenitic stainless steel according to claim 2, wherein the coating layer is a build-up weld coating layer made of stainless steel containing 0.003 to 0.4%.