JPH07268455A - Production of cr-ni stainless alloy free from microracking in hot rolling - Google Patents

Abstract

PURPOSE:To prevent microcracking causing scab at the time of producing a Cr-Ni stainless alloy. CONSTITUTION:This alloy is a stainless alloy having a composition which is composed essentially of 16-35%, by weight, Cr and 7-30% Ni and in which the value of delta(cal) represented by equation delta(cal)=3Creq-2.8Nieq-19.8 is regulated to >4-10. This alloy can be produced by performing cooling, at the time of casting, at a rate of >=30 deg.C/S through the temp. region between 1350 and 1000 deg.C and at a rate of >=10 deg.C/S through the temp. region between 1000 and 500 deg.C and subjecting a slab, in which the region where the ratio between the Ni concentration in an Ni segregation zone, in a trough part of oscillation mark in the surface layer part of slab, and the average Ni concentration is >=1.15 is regulated to <=200mum, to heating at the tenp. in the range between 1000 and Tgamma deg.C represented by equation Tgamma=(105+Nieq-3.9 Creq)/(0.07-1.95X10<-3>Creq) and then to hot rolling. In the equations, Creq=Cr+1.5Si+Mo+0.5(Nb+Ti) and Nieq=Ni+0.5Mn+0.5Cu+30C+30N are satisfied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manufacturing method for preventing minute cracks generated on the surface of a slab during hot rolling of a Cr-Ni type stainless alloy.

[0002]

2. Description of the Related Art Since Cr-Ni type stainless alloys are high alloys, they have poor hot workability, and various studies have been conducted to prevent cracks from occurring during hot rolling. In particular, cracks that occur in the slab edge and the edge of the hot-rolled sheet, which are called ear cracks, are major problems in manufacturing, such as the occurrence of a possibility of manufacturing and a significant decrease in yield. Various investigations have been made for large cracks that occur during the hot rolling process, and nowadays, it is less likely that manufacturing will not be possible due to optimization of components and rolling conditions.

On the other hand, apart from such large cracks related to the possibility of manufacturing, they are hardly detected in the hot rolling process, and are not detected until after the hot rolling process such as pickling or cold rolling process. Defects that are called baldness may occur. Defects such as bald defects are fatal defects in the hot-rolled sheet surface where the surface quality is important, and require a reconditioning process such as re-pickling and maintenance with a grinder. In some cases, it is a major factor of cost increase in the manufacturing process of equal-thickness plates and thin plates that cannot be commercialized at all in terms of surface quality.

Conventionally, for the bald defects which cannot be found in the hot rolling stage and are found after pickling or in the cold rolling process, various examinations are conducted from the casting process to the hot rolling and annealing processes. Has been done.

In particular, since the hairline flaw is a minute crack in the hot rolling process, from the viewpoint of preventing the crack, it is disclosed in JP-A-57-161.
In Japanese Patent No. 53, the Cr equivalent and the Ni equivalent of the steel composition are regulated and δ
(cal) = 3 (Cr + Mo + 1.5Si + 0.5Nb)-
2.8 (Ni + 0.5Mn + 0.5Cu) -84 (C +
N) A technique for ensuring hot workability by setting δ (cal) determined by -19.8 to 4 or less is disclosed. Also δ −
Regarding the handling of Fe, it is conventionally necessary to sufficiently perform soaking (diffusion heat treatment) in order to prevent ear cracking of an austenitic stainless steel having a two-phase structure containing a large amount of δ-ferrite. However, there is no disclosure of heating conditions themselves for preventing ear cracks and for minute cracks that cause bald spots.

From the viewpoint of the slab structure, Japanese Patent Laid-Open No. 57-
No. 127554 discloses the N content of austenitic stainless steel and the tundish temperature (ΔT) during casting in the casting stage.
There is disclosed a technique of controlling the relationship of (1) to prevent coarsening of crystal grains to enhance hot workability. From the viewpoint of improving the microstructure of the surface layer, in Japanese Patent Publication No. 9651/1990, a slab having a controlled Si content of austenitic stainless steel is shot-blasted before insertion into a heating furnace to introduce a processing layer into the surface layer and re-heat it during heating. A technique is disclosed in which crystallization is performed and the crystal grains in the surface layer of the slab are refined to prevent cracking. In addition, as one that focuses on the scale during heating, Japanese Patent Publication No. 4-4
JP-A-8865 discloses a technique for preventing bald spots by controlling sol Al to regulate the oxygen concentration during slab heating to 0.5 to 5%. However, the above method is not perfect in terms of preventing microcracks.

[0007]

The present invention is based on the above-mentioned Cr.
To provide a Cr-Ni-based stainless alloy by improving the flaws without increasing the process load for preventing the flaws, in order to improve the microcracks and the flaws called bald flaws that occur during the hot rolling of the Ni-based stainless alloy. With the goal.

[0008]

The gist of the present invention is as follows. (1)% by weight, C: 0.002 to 0.08%,
Si: 2.0% or less, Mn: 10% or less,
P: 0.040% or less, S: 0.008% or less, O: 0.005% or less, Cr: 16-
35%, Ni: 7 to 30%, Mo: 0.
01-8%, Cu: 0.01-4%, N
: 0.003 to 0.3%, the balance consisting of Fe and unavoidable impurities, δ (cal) = 3 (Cr + 1.5 × Si + Mo)
+ 0.5 × Nb + 0.5 × Ti) -2.8 (Ni + 0.
5 × Mn + 0.5 × Cu) -84 (C + N) -19.8
Δ (cal) is more than 4 and less than 10 and the cooling of the slab surface during continuous casting is from 1350 ° C to 1000 ° C at an average cooling rate of more than 30 ° C / S, from 1000 ° C to 500 ° C.
The average cooling rate up to ℃ is 10 ℃ / S or more, and the Ni segregation zone depth enriched by 1.15 times or more than the average Ni concentration existing in the oscillation mark valley of the slab surface layer is 200 μm or less from the oscillation mark valley. The slab that is
During hot rolling, 1000 ° C or higher and Tγ (° C) = (10
5 + Nieq-3.9 × Creq) / (0.07-1.95)
After heating to a temperature T (° C.) not higher than × 10 ⁻³ × Creq),
A method for producing a Cr-Ni-based stainless alloy for preventing cracking in hot rolling, characterized by hot rolling. (Here, Creq = Cr (%) + 1.5 × Si (%) + M
o (%) + 0.5 × Nb (%) + 0.5 × Ti (%) Nieq = Ni (%) + 0.5 × Mn (%) + 0.5 × C
u (%) + 30 × C (%) + 30 × N (%)) (2) No surface flaw occurs in the hot rolling described in (1) above using a slab containing Al: 0.05% or less. A manufacturing method of a Cr-Ni system stainless steel alloy. (3) Further, Al: 0.05% or less, Ca: 0.001
The manufacturing method of the Cr-Ni type | system | group stainless alloy which does not generate | occur | produce a surface flaw by the hot rolling as described in said (1) using the slab containing 0.005%. (4) Further, Nb: 0.01 to 1.5%, Ti: 0.0
Cr-Ni that does not generate surface defects in the hot rolling described in (1), (2) or (3) above, using a slab containing one or two of 1 to 1.0%. Of producing a stainless steel alloy.

[0009]

According to the invention of the present application, it is possible to prevent bald defects due to minute cracks generated during hot rolling. The present invention will be described in detail below. The present inventors have studied in detail how to prevent minute cracks and bald marks. In particular, it was examined to clarify the relationship with the cast structure by investigating the correspondence between the microcracking locations that occur during hot rolling and the slab structure.

As a result, it has been found that the microcrack generation locations of the slab after hot rolling are largely related to the oscillation marks formed during casting. In particular, the peak portion of the oscillation mark is often cracked at the interface between δ-ferrite and austenite (γ), and there is almost no microcrack in the portion where δ-ferrite does not exist. It was also found that the valley of the oscillation mark had almost no δ-ferrite, but cracked at the γ grain boundary.
Therefore, in order to prevent minute cracks, it is necessary to prevent minute cracks due to δ-ferrite remaining in the peaks of the oscillation marks and to establish a method for preventing γ grain boundary cracks in the valleys of the oscillation marks. There is.

As a result of various studies on these two points, it became clear that the δ-ferrite in the peak portion of the oscillation mark causes unmelted residue during heating when the cooling rate during cooling after solidification is small. It was Long-time heating is also effective to prevent undissolved residue during heating, but at the same time it will cause defects due to scale formation,
Not a good idea. In order to prevent flaws due to scale and further prevent microcracks due to unmelted residue of δ-ferrite in the above oscillation mark peaks, δ-ferrite produced during solidification undergoes δ → γ transformation in the γ stable region thereafter. It turned out that it would be fine to make it fine when awakening. By making the δ-ferrite fine, variations in the size of the δ-ferrite can be eliminated and the δ-ferrite can be eliminated in a short time. Especially the thickness of continuous cast slab is 200
mm, width 1350 for width 800-1500 mm
By quenching the temperature range of up to 1000 ° C. so that the average cooling rate of the slab surface exceeds 30 ° C./S, the δ → γ transformation rapidly occurs, so that a fine δ + γ structure can be obtained.

This quenching effect makes δ fine when δ (cal) is 4 or more, and when it is 4 or less, the γ phase is stable immediately after solidification, so that the temperature range of 1350 to 1000 ° C. is 30 ° C./S. A fine δ + γ structure cannot be obtained even if quenching is performed to exceed the range. When the δ → γ transformation does not occur rapidly, δ is not fine and is locally accumulated, or coarse δ due to aggregation is observed.

In addition, in order to extinguish the δ-ferrite in the heating before hot rolling so as not to become the starting point of the microcracks, the heating temperature is a temperature range in which the δ-ferrite is not structurally stable, that is, in the present invention. Must be heat-treated in the γ single-phase region where δ-ferrite does not exist in the equilibrium diagram. In particular, when heating is performed in a temperature range in which δ-ferrite increases, δ-ferrite increases from the cast piece stage and fine cracks due to δ-ferrite occur.

However, since stainless steel is a multi-component system, the upper limit temperature of the heating temperature cannot be clearly determined for each component system. The present inventors have conducted a detailed study and experimentally found a temperature at which δ-ferrite does not reprecipitate from the viewpoint of preventing reprecipitation of δ-ferrite due to inappropriate heating temperature, particularly overheating, as shown by the following equation. Γ that can be obtained by Creq and Nieq
Clarified the maximum temperature of single phase. Tγ (° C.) = (Nieq-3.9 × Creq + 105) /
(0.07-1.95 × 10 ⁻³ × Creq) Here, Creq = Cr (%) + 1.5 × Si (%) + Mo
(%) + 0.5 × Nb (%) + 0.5 × Ti (%) Nieq = Ni (%) + 0.5 × Mn (%) + 0.5 × C
u (%) + 30 × C (%) + 30 × N (%)

Therefore, it becomes possible to prevent the reprecipitation of δ-ferrite during heating by heating at a temperature not higher than Tγ which is the γ single phase.

Further, in the alloy system having δ (cal) of more than 4 and less than 10 in the present invention, by setting the temperature range of 1350 to 1000 ° C. to 30 ° C./S or more as the cooling condition during continuous casting, δ− Since the ferrite becomes fine, the δ-ferrite during heating tends to disappear, and if the heating temperature is 1150 ° C or higher, the microcracking due to δ-ferrite can be prevented by soaking the slab surface layer for 30 minutes or more. Became.

Further, the cracking of the γ grain boundary in the valley portion of the oscillation mark, which became the starting point of the microcracking in correspondence with the casting structure, was examined. As a result, it was found that the valley portion of the oscillation mark may have a Ni-concentrated portion in the oscillation valley portion as shown in FIG. When the relationship between the segregation of the valleys of the oscillation marks and the microcracks was investigated, it was found that there was a large relationship. If this Ni-enriched region is defined as a Ni segregation zone, and the distance from the oscillation mark valley is defined as the Ni segregation zone depth, the higher the Ni concentration in the segregation zone in the valley of the oscillation mark, and the depth of the Ni segregation zone. It was clarified that the larger the value, the more remarkable the occurrence of microcracks. This crack occurs when the average Ni concentration (CNi
It was revealed that the concentration was 1.15 times higher than that of AVE) and the depth thereof was more than 200 μm.
Therefore, N of the Ni segregation zone at the valley of the oscillation mark
The i concentration is 1.15 times higher than the average Ni concentration (CNiAVE). If the Ni segregation zone depth is 200 μm or less, the γ grain boundary cracks at the valley of the oscillation mark are prevented to prevent the occurrence of bald defects. It became clear that it could be done.

The reason why the Ni segregation zone at the valley of the oscillation mark becomes a starting point for the generation of microcracks and further causes bald defects, is that Ni itself reduces ductility.
It was also found that the Ni segregation portion is a concentrated molten steel at the time of solidification, so that the impurities are also concentrated, and the concentration of S is particularly remarkable.
At the same time, S forms concentrated Mn and MnS and segregates at grain boundaries. Therefore, in the Ni segregation zone, the volume fractions of concentrated Ni and MnS are increased and the segregation of concentrated S is also added, so that the ductility is reduced as compared with the portion other than the Ni segregation zone. Therefore, the valley portion of the oscillation mark is locally low ductility in the cast piece stage, and although this degree of segregation is reduced in the heating stage, it is not possible to completely homogenize and minute cracks occur during hot rolling. It is easy to do and it causes baldness.

Oscillation mark of CC slab Valley N
Regarding the formation of the i segregation zone, there are mechanisms such as shell remelting during solidification and overflow during oscillation,
It can also be considered that the shell partially cracked due to insufficient ductility of the shell during solidification and segregated molten steel flowed out. Therefore, in order to prevent the concentration of Ni in the oscillation mark valley, it is important to optimize the casting conditions, especially the powder, the oscillation conditions, the casting speed, the fluctuation of the molten metal level, etc., and to prevent the solidified shell from cracking. It is important to plan.

FIG. 2 shows the effect of δ (cal) on the ductility of SUS304 steel at 50 ° C. just below the melting point. It was found that the higher δ (cal), the higher the ductility and the more difficult it is to crack. A detailed study of the relationship between the ductility just below the melting point and δ (cal) revealed that the presence of δ-ferrite, which has a higher solid solubility for impurities such as S and P than austenite at high temperatures just below the melting point, promotes detoxification of impurities. To be done. It was found that the higher the δ (cal) is, the larger the volume fraction of δ-ferrite at 50 ° C. just below the melting point is, the harmless the influence of impurities and the improved ductility. Especially in relation to the ductility of the shell during continuous casting, the cross-sectional shrinkage ratio (drawing) of 20% or more at 50 ° C just below the melting point
If there is, the shell is kept good without cracking. Therefore, increasing δ (cal) makes it possible to prevent cracking during casting of the CC cast. Therefore, in the alloy system of the present invention where δ (cal) is 4 or more, the larger δ (cal), the smaller the cracking susceptibility during solidification, and the cracking during solidification causes almost no problem. However, even if δ (cal) exceeds 10, the effect of preventing cracking during solidification does not change,
Actually, the δ-ferrite becomes too stable and becomes hard to disappear during heating, the heating time required for the disappearance of the δ-ferrite becomes long, and the possibility of causing defects due to scale increases.

In the present invention, δ (cal) exceeds 4 and 10
As shown in FIG. 2, the crack susceptibility during solidification is low, and the larger δ (cal) is, the larger the volume fraction of δ-ferrite immediately below the melting point is.
Since the volume fraction of the δ-ferrite phase, which is a bcc phase having a better diffusibility than that of c, is large, the diffusion of Ni is promoted, and the N of the Ni segregation zone formed in the valley of the oscillation mark is formed.
The diffusion of i is also promoted, and the degree of segregation of the Ni segregation zone can be reduced.

As described above, in order to prevent bald defects, it is necessary to prevent microcracks caused by δ-ferrite and microcracks caused by the oscillation valley Ni segregation, and δ (cal) is 4 It is possible to finely disperse δ-ferrite by defining the components so as to exceed 10 and not more than 10 and cooling the temperature range of 1350 to 1000 ° C. at 30 ° C./S or more. Further, by setting 1000 to 500 ° C. to 10 ° C./S or more, it is possible to prevent the coagulation and coarsening of δ-ferrite, and by further optimizing the heating conditions before rolling, it is possible to prevent microcracks that cause bald defects. It became possible.

These measures for preventing bald spots are realized by the Cr-Ni type stainless alloys of the following components. % By weight,
C: 0.002-0.08%, Si: 2.0% or less, M
n: 10% or less, P: 0.040% or less, S: 0.00
8% or less, O: 0.005% or less, Cr: 16 to 35
%, Ni: 7 to 30%, Mo: 0.01 to 8%, Cu:
0.01 to 4%, N: 0.003 to 0.3%, Al: 0.05% or less is added if necessary, and Nb: 0.01 to 1.5% and Ti: are selected elements. 0.01-1.0%
Containing 1 or 2 of them, and further Ca: 0.00
1 to 0.005%, rare earth element (REM): 0.05 to
One or two of 0.5% may be contained, and the balance is Fe and inevitable impurities.

The reasons for limiting the components will be described below. C: C is harmful to the corrosion resistance of the stainless alloy, but a certain amount of C is necessary in terms of strength. 0.002%
If the carbon content is very low, the production cost will be high. In addition, 0.
If it exceeds 08%, the corrosion resistance is significantly deteriorated, so the component range is set to 0.002 to 0.08%. Si: Si is used as a deoxidizing element for stainless alloys, but even if added in excess of 2%, the deoxidizing effect saturates, and the hot workability deteriorates and the frequency of bald spots increases. Add up to 2%.

Mn: Mn is a γ-stabilizing element and is an effective element because it can be added as a substitute for Ni and has a deoxidizing effect, but even if added in excess of 10%, its effect is obtained. Is saturated and corrosion resistance is deteriorated, so it is added at 10% or less. Cr: Cr is a basic component of the stainless alloy, and it is necessary to add 16% or more from the viewpoint of corrosion resistance. But 35%
If it is added in excess of 10%, the corrosion resistance will be saturated, and further, in terms of hot workability, precipitation of intermetallic compounds will be promoted and hot workability will be deteriorated, which will cause bald defects, so the range of Cr is 16-.
It was set to 35%.

Ni: Ni is a basic component of a stainless alloy together with Cr.
Add in the range of 30%. If it is less than 7%, austenite becomes unstable in the alloy of the present invention and a large amount of δ-ferrite exists, so that δ can be obtained by the method of the present invention.
-Because the ferrite cannot be controlled and hot workability is poor, bald defects occur. Further, from the relationship between the Cr amount and δ (cal), the Ni amount of 30% or less is sufficient in the present invention, and even if it is added in excess of this amount, the effect is saturated in terms of preventing bald spots and the cost becomes high. The upper limit was 30%.

Mo: Mo is an important additive element for ensuring the corrosion resistance, and an effect can be seen when added in an amount of 0.01% or more. Further, even if it exceeds 8%, the corrosion resistance is saturated, and further, the precipitation of intermetallic compounds is promoted so that the hot workability is deteriorated and the bald defects cannot be prevented even by the method of the present invention, so the upper limit was made 8%. N: N is a desirable element from the viewpoint of corrosion resistance and strength, which can be used as a substitute for expensive Ni for stabilizing the γ phase. However, if it is 0.003% or less, the melting cost will be greatly increased, and even if it is added in excess of 0.3%, its effect will be saturated, and beyond the solid solubility, pinholes etc. will be formed in the slab. The upper limit was set to 0.3% to cause defects. P: P is a harmful element from the viewpoint of corrosion resistance and hot workability, and in particular, it deteriorates the ductility immediately after casting, so it is desirable to reduce it as much as possible from the viewpoint of preventing cracking of the slab surface layer, and its component range is 0.04. % Or less. S: S is an element harmful to the corrosion resistance and the hot workability, and has a great effect on the ductility of the slab surface layer immediately after casting and the hot workability at the time of hot rolling. A lower content is desirable because it causes a flaw. Depending on the method of the present invention, when the content exceeds 0.008%, S
The upper limit is 0.008 because defects are more likely to occur.
%. Cu: Cu improves the corrosion resistance of the stainless alloy to 0.0
Add at 1% or more. However, even if added in excess of 4%, the effect will be saturated, and further the hot workability will be deteriorated and defects will occur, so the addition range is made 0.01 to 4%.

Nb: Nb has the effect of fixing C and improving corrosion resistance, so 0.01% or more of 1.
It can be added at 5% or less. Even if added over 1.5%, the improvement effect is saturated, and the hot workability is deteriorated to cause defects due to poor hot workability.
Selective addition at 1.5%. Ti: Ti fixes C like Nb and improves corrosion resistance. Moreover, since it has an effect of fixing O in coexistence with Ca and suppressing the formation of oxides of Si and Mn, it can be added in an amount of 0.01% or more. Further, when added in excess of 1.0%, surface defects due to Ti oxide frequently occur, so the range was made 0.01 to 1.0%.

Al: Al is a strong deoxidizer and is added to enhance deoxidation. However, even if added over 0.05%, the effect is saturated, and surface defects due to the oxide of Al are more likely to occur.
It was set to 5% or less. Ca: Ca is a strong deoxidizing and desulfurizing agent and is an element effective for improving hot workability.
It is selectively added in the range of%. If the content is 0.001% or less, the effect is not remarkable, and the effect is saturated even if 0.005% or more is added. O: O is an element that is extremely harmful to hot workability, and it is desirable to reduce the content thereof as much as possible, so the content was made 0.005% or less.

[0030]

EXAMPLES As examples of the present invention, CC cast pieces were manufactured under the process conditions shown in Table 1 for the alloys shown in A to U, further heated under the heating conditions shown in the table, and then hot rolled under normal conditions and wound up.
The state of occurrence of bald spots was evaluated by a method of forming a thin plate by pickling to cooling, or a method of rolling a thick plate and performing pickling by a usual method.

The steels A to N produced by the method of the present invention did not cause bald marks and good products were obtained. On the other hand, O alloy has δ (c
al) deviated from the conditions of the present invention, and bald defects due to δ-ferrite occurred. The δ (cal) of the P alloy deviated from the condition of the present invention, and a bald defect caused by Ni segregation occurred. Q alloy is 13
The cooling rate at 50 to 1000 ° C. was small, and bald defects occurred. The R alloy has a low cooling rate of 1000 to 500 ° C.
-Ferrite was coarsened and bald defects due to δ-ferrite occurred. The S alloy had a high heating temperature and δ-ferrite was precipitated to cause bald defects. In the T alloy and the U alloy, the Ni segregation zone in the valley portion of the oscillation mark was large, and a dent defect was generated due to poor ductility of the valley portion of the oscillation mark. It is clear that these O to U alloys are significantly different from the present invention in that the yield loss is remarkably generated on both sides, the product yield is lowered, and a repair process such as a grinder is required. The effect became clear.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

According to the present invention, it has become possible to prevent the occurrence of bald defects due to microcracks, which were difficult to find in the conventional hot rolling process and were a major cause of yield reduction.

[Brief description of drawings]

FIG. 1 is a schematic view showing an outline appearance of a continuously cast slab and a Ni segregation zone at a valley portion of an oscillation mark.

FIG. 2 is a diagram showing an influence of δ (cal) on ductility just below a melting point.

Claims (4)

[Claims] 1. By weight%, C: 0.002-0.08%, Si: 2.0% or less, Mn: 10% or less, P: 0.040% or less, S: 0.008% or less, O: 0.005% or less, Cr: 16 to 35%, Ni: 7 to 30%, Mo: 0.01 to 8%, Cu: 0.01 to 4%, N: 0.003 to 0.3% The balance consists of Fe and inevitable impurities, and δ (cal) = 3
(Cr + 1.5 × Si + Mo + 0.5 × Nb + 0.5 ×
Ti) -2.8 (Ni + 0.5xMn + 0.5xCu)
-84 (C + N) -19.8 has a δ (cal) of more than 4 and 10 or less, and cooling of the slab surface during continuous casting is 13
The average cooling rate from 50 ° C to 1000 ° C exceeds 30 ° C / S, and the average cooling rate from 1000 ° C to 500 ° C is 1
The Ni segregation zone depth, which was 1.15 times or more higher than the average Ni concentration existing in the oscillation mark valley portion of the slab surface layer, was 20 ° C or more from the oscillation mark valley.
A slab of 0 μm or less is heated to 1000 ° C.
Above and Tγ (° C.) = (105 + Nieq-3.9 × Cr
eq) / (0.07-1.95 × 10 ⁻³ × Cr eq) or less and then hot-rolled, which prevents microcracking in hot-rolling. -A method for producing a Ni-based stainless alloy. (Here, Creq = Cr (%) + 1.5 × Si (%) + M
o (%) + 0.5 × Nb (%) + 0.5 × Ti (%) Nieq = Ni (%) + 0.5 × Mn (%) + 0.5 × C
u (%) + 30 x C (%) + 30 x N (%)) 2. The slab according to claim 1, further comprising Al:
A method for producing a Cr-Ni-based stainless alloy for preventing microcracking in hot rolling, characterized by containing 0.05% or less. 3. The slab according to claim 1, further comprising Al:
0.05% or less, Ca: 0.001-0.005% was contained, The manufacturing method of the Cr-Ni type | system | group stainless alloy which prevents the microcrack in hot rolling characterized by the above-mentioned. 4. The slab according to claim 1, further comprising Nb: 0.01 to 1.5% and Ti:
The method for producing a Cr-Ni-based stainless alloy for preventing microcracking in hot rolling according to claim 1, wherein a slab containing one or two of 0.01 to 1.0% is used.