CN116288070A - A kind of stainless steel for welding strip and its manufacturing method - Google Patents

Abstract

The invention relates to the technical field of stainless steel for welding strips and its preparation technology, and discloses a stainless steel for welding strips and a manufacturing method thereof to solve the problems existing in stainless steel for welding strips in the prior art. The stainless steel for welding strips is calculated by mass percentage. Contains the following components: C: 0.015‑0.025%, Si: 0.30‑0.40%, Mn: 1.80‑1.90%, P: ≤0.015%, S: ≤0.002%, Cr: 19.6‑20.0%, Ni: 10.7‑10.8 %, Nb: 0.50‑0.60%, N: 0.03‑0.04%, Co: ≤0.05%, Al: ≤0.005%, and the balance is Fe. The manufacturing method includes steps such as steelmaking and continuous casting, hot rolling, and cold rolling. The present invention adopts pure nickel, low-P ferrochrome and molten iron for production, which ensures the low P content of stainless steel for welding strips, and reduces the use of welding strips from the source. The low aluminum content of stainless steel reduces the content of Al ₂ O ₃ in inclusions, improves the thermoplasticity of the slab, and increases the temperature after secondary heating, which solves the problem of high rolling load of high-niobium austenitic stainless steel. The welding strip is welded with two coils of stainless steel and rolled together. In addition, the leading strip is added at the head and tail, which improves the yield and reduces the production cost.

Description

A kind of stainless steel for welding strip and its manufacturing method

technical field

The invention relates to the technical field of stainless steel for welding strips and its preparation, in particular to stainless steel for welding strips and a manufacturing method thereof.

Background technique

In recent years, the strip surfacing technology at home and abroad has been greatly developed. The strip surfacing is a welding method that uses "metal strips" instead of welding wires as electrodes, and is carried out under a layer of smelting flux or ceramic flux. Stainless steel welding strip is the key technology of strip surfacing welding, and it is also the main welding material. Among the stainless steel used for welding strips, 309L and 347L stainless steel are usually used together, 309L is mainly used for welding backing, and 347L is used for the outer layer. 309L stainless steel for welding strips and its manufacturing methods are basically mature, but the production of 347L stainless steel is extremely difficult. On the one hand, high ferrite content is required in the stainless steel structure for welding strips to avoid welding cracks during welding, but austenitic stainless steel Medium to high ferrite content will lead to two-phase rolling during hot rolling, edge cracking and peeling defects. In response to this problem, application number 202110350457.5, name: a production method of stainless steel hot-rolled coils for welding strips, the control measures adopted are to use short billets and roll thick gauges at low temperature. However, 347L stainless steel has high content of niobium, high strength, heavy rolling load at low temperature, and easy stacking of steel. In addition, short billets are used to roll thick gauges, and the yield is low.

Application number: 202011054785.2, name: A production method for improving the high-temperature performance of 347H stainless steel. It is disclosed that the composition of 347H stainless steel is C 0.04-0.10%, Si 0.30-0.75%, Mn<2.00%, P<0.03%, S< 0.01%, Cr 17.0-19.0%, Ni 9.0-13.0%, Nb 0.40-1.0%, Cu0.10-0.75%, and the balance is Fe. Due to high C content and low chromium content, the organization cannot meet the requirements of customers for ferrite content. In addition, trace elements such as P, S, and Co cannot meet the requirements of end users.

Contents of the invention

The purpose of the present invention is to solve the problems existing in the stainless steel for welding strips in the prior art, and to provide a stainless steel for welding strips, which comprises the following components in terms of mass percentage: C: 0.015-0.025%, Si: 0.30-0.40 %, Mn: 1.80-1.90%, P: ≤0.015%, S: ≤0.002%, Cr: 19.6-20.0%, Ni: 10.7-10.8%, Nb: 0.50-0.60%, N: 0.03-0.04%, Co : ≤0.05%, Al: ≤0.005%, the balance is Fe.

Further, Cr+1.5Si+Nb=Creq;

Ni+30×(C+N)+0.5Mn=Nieq;

1.52≤Creq/Nieq≤1.64.

The invention also discloses a method for manufacturing stainless steel for welding strips, which includes the following steps:

Step 1: Steelmaking and continuous casting, through induction electric furnace + dephosphorized molten iron - AOD converter - LF refining furnace - continuous casting process to produce stainless steel for welding strips;

The induction furnace adopts pure nickel and low P ferrochrome as ingredients, the P content of low P ferrochrome is ≤0.02%, and the P content of dephosphorized hot metal is ≤0.007%;

AOD uses electrolytic manganese, low-aluminum ferrosilicon, and low-Al ferro-niobium, among which the Al content of low-alumina-ferrosilicon and low-Al niobium ferro-niobium is ≤0.1%, and niobium alloying is completed in the AOD stage;

The superheating degree of the tundish is 20°C-35°C, the current intensity of electromagnetic stirring is 1550A-1750A, and finally a slab of 220mm×1260mm×(7000-8000)mm is made;

Step 2: hot rolling, produced by the process of primary heating of slab-secondary heating of slab-rough rolling-steel rolling-coiling;

Among them, the primary heating temperature of the slab is 1100-1140°C, and the heating time is 250-300min; the secondary heating temperature of the slab is 1230-1250°C, and the heating time is 230-250min;

The thickness of stainless steel hot-rolled coil for welding strip is 5.5mm;

Step 3: Cold rolling, produced according to the process of conventional austenitic stainless steel hot annealing pickling-20-roll mill rolling-cold annealing pickling, when the welding strip uses stainless steel hot-rolled coils on the hot annealing pickling line, one roll head A 6-meter 304 stainless steel leader is connected at the end, and another 6-meter 304 stainless steel leader is connected at the end.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention adopts pure nickel, low-P ferrochrome and molten iron to produce, which ensures the low P content of the stainless steel used for the welding strip.

2. The AOD of the present invention uses electrolytic manganese, low-aluminum ferrosilicon (Al content ≤ 0.1%), and low-Al ferroniobium (Al content ≤ 0.1%). Niobium alloying is completed in the AOD stage, which reduces the use of stainless steel for welding strips from the source. Low aluminum content reduces the content of Al ₂ O ₃ in inclusions.

3. The present invention improves the thermoplasticity of the slab by controlling the superheat of the tundish to 25-35°C and applying electromagnetic stirring.

4. The invention adopts the short billet, which solves the problem of low temperature at the head and tail of the steckel mill. After heating the slab once, the reticular ferrite is transformed into dots, which improves the thermoplasticity. The secondary heating increases the temperature, which solves the problem of high rolling load of high-niobium austenitic stainless steel.

5. In the present invention, two coils of stainless steel are welded together for rolling the welding strip. In addition, leader strips are added at the head and tail, which improves the yield and reduces the production cost.

The stainless steel molten steel for welding strips of the invention has excellent purity, and can ensure good surface quality when rolled to a thickness specification below 0.5mm. In addition, the stainless steel for welding strips of the present invention has low content of trace elements and can be applied to high-end fields such as nuclear power.

Detailed ways

The invention will be further described below in conjunction with specific embodiments.

Example 1:

A stainless steel for welding strips, the composition of which contains in mass %, C: 0.015%, Si: 0.40%, Mn: 1.80%, P: 0.015%, S: 0.002%, Cr: 20.0%, Ni: 10.7% , Nb: 0.60%, N: 0.03%, Co: 0.05%, Al: 0.005%, and the balance is Fe and unavoidable inclusion elements.

In this example, Creq/Nieq: 1.64.

Its manufacturing method is:

Step 1: Steelmaking and continuous casting, through induction electric furnace + dephosphorized hot metal - AOD converter - LF refining furnace - continuous casting process to produce stainless steel for welding strips.

The induction furnace adopts pure nickel and low P ferrochrome as ingredients, the P content of low P ferrochrome is 0.02%, and the P content of dephosphorized hot metal is 0.007%.

AOD uses electrolytic manganese, low-aluminum ferrosilicon, and low-Al ferroniobium, among which the Al content in low-alumina ferrosilicon and low-Al ferroniobium is 0.1%, and niobium alloying is completed in the AOD stage.

The superheating degree of the tundish is 20°C, the electric current intensity of the electromagnetic stirring is 1750A, and finally a slab of 220mm×1260mm×7000mm is made.

Step 2: Hot rolling, produced by the process of primary heating of slab - secondary heating of slab - rough rolling - rolling in a coil rolling mill - coiling.

The primary heating temperature of the slab is 1140°C, the heating time is 300min, the secondary heating temperature of the slab is 1250°C, the heating time is 250min, and the thickness of the stainless steel hot-rolled coil for the welding strip is 5.5mm.

Step 3: Cold rolling, produced according to the process of conventional austenitic stainless steel hot annealing pickling-20-roll mill rolling-cold annealing pickling, when the welding strip uses stainless steel hot-rolled coils on the hot annealing pickling line, one roll head A 6-meter 304 stainless steel leader is connected at the top, and a 6-meter 304 stainless steel leader is connected at the end of the other roll. The two welding strips are connected with the stainless steel without leader. The two coils are rolled together by a 20-roll rolling mill to reduce the head and tail. Unrolled, improve yield.

Example 2:

A stainless steel for welding strips, the composition of which contains in mass %, C: 0.025%,

Si: 0.30%, Mn: 1.90%, P: 0.014%, S: 0.0015%, Cr: 19.6%, Ni: 10.8%, Nb: 0.50%, N: 0.04%, Co: 0.02%, Al: 0.004%, The balance is Fe and inevitable inclusion elements, Creq/Nieq: 1.52.

Its manufacturing method is:

Step 1: Steelmaking and continuous casting, through induction electric furnace + dephosphorized hot metal - AOD converter - LF refining furnace - continuous casting process to produce stainless steel for welding strips.

The induction furnace adopts pure nickel and low P ferrochrome as ingredients, the P content of low P ferrochrome is 0.018%, and the P content of dephosphorized hot metal is 0.006%.

AOD uses electrolytic manganese, low-aluminum ferro-silicon, and low-Al ferro-niobium, of which the Al content in low-alumina-ferrosilicon and low-Al ferro-niobium is 0.06%, and niobium alloying is completed in the AOD stage.

The superheating degree of the tundish is 35°C, the electric current intensity of the electromagnetic stirring is 1550A, and finally a slab of 220mm×1260mm×8000mm is made.

Step 2: Hot rolling, produced by the process of primary heating of slab - secondary heating of slab - rough rolling - rolling in a coil rolling mill - coiling.

Among them, the primary heating temperature of the slab is 1100°C, the heating time is 250min, the secondary heating temperature of the slab is 1230°C, the heating time is 230min, and the thickness of the stainless steel hot-rolled coil for the welding strip is 5.5mm.

Step 3: Cold rolling, produced according to the process of conventional austenitic stainless steel hot annealing pickling-20-roll mill rolling-cold annealing pickling, when the welding strip uses stainless steel hot-rolled coils on the hot annealing pickling line, one roll head A 6-meter 304 stainless steel leader is connected at the top, and a 6-meter 304 stainless steel leader is connected at the end of the other roll. The two welding strips are connected with the stainless steel without leader. The two coils are rolled together by a 20-roll rolling mill to reduce the head and tail. Unrolled, improve yield.

Example 3:

A stainless steel for welding strips, the composition of which is contained in mass %, C: 0.018%;

Si: 0.32%, Mn: 1.85%, P: 0.013%, S: 0.0018%, Cr: 19.65%,

Ni: 10.75%, Nb: 0.54%, N: 0.034%, Co: 0.04%, Al: 0.003%.

The balance is Fe and inevitable inclusion elements, Creq/Nieq: 1.56.

Its manufacturing method is:

Step 1: Steelmaking and continuous casting, through induction electric furnace + dephosphorized hot metal - AOD converter - LF refining furnace - continuous casting process to produce stainless steel for welding strips.

The induction furnace adopts pure nickel and low P ferrochrome as ingredients, the P content of low P ferrochrome is 0.019%, and the P content of dephosphorized hot metal is 0.006%.

AOD uses electrolytic manganese, low-aluminum ferrosilicon, and low-Al ferro-niobium, among which low-aluminum-ferrosilicon (0.08% Al content) and low-Al ferro-niobium (0.09% Al content), niobium alloying is completed in the AOD stage.

The superheating degree of the tundish is 30°C, the electric current intensity of the electromagnetic stirring is 1600A, and finally a slab of 220mm×1260mm×7500mm is made.

Step 2: Hot rolling, produced by the process of primary heating of slab - secondary heating of slab - rough rolling - rolling in a coil rolling mill - coiling.

Among them, the primary heating temperature of the slab is 1120°C, the heating time is 280min, the secondary heating temperature of the slab is 1240°C, the heating time is 240min, and the thickness of the stainless steel hot-rolled coil for the welding strip is 5.5mm.

Step 3: Cold rolling, produced according to the process of conventional austenitic stainless steel hot annealing pickling-20-roll mill rolling-cold annealing pickling, when the welding strip uses stainless steel hot-rolled coils on the hot annealing pickling line, one roll head A 6-meter 304 stainless steel leader is connected at the top, and a 6-meter 304 stainless steel leader is connected at the end of the other roll. The two welding strips are connected with the stainless steel without leader. The two coils are rolled together by a 20-roll rolling mill to reduce the head and tail. Unrolled, improve yield.

Claims (3)

1. The stainless steel for the welding strip is characterized by comprising the following components in percentage by mass: c:0.015-0.025%, si:0.30-0.40%, mn:1.80-1.90%, P: less than or equal to 0.015 percent, S: less than or equal to 0.002 percent, cr:19.6-20.0%, ni:10.7-10.8%, nb:0.50-0.60%, N:0.03-0.04%, co: less than or equal to 0.05 percent, al: less than or equal to 0.005 percent, and the balance of Fe.

2. The stainless steel for a solder strip according to claim 1, wherein:

the cr+1.5si+nb=creq;

Ni+30×（C+N）+0.5Mn＝Nieq；

1.52≤Creq/Nieq≤1.64。

3. a method for manufacturing the stainless steel for a solder strip according to claims 1-2, characterized in that: the method comprises the following steps:

step 1: steelmaking continuous casting, namely producing stainless steel for welding strips through an induction furnace, dephosphorized molten iron, an AOD converter, an LF refining furnace and a continuous casting process;

the induction furnace adopts pure nickel and low-P ferrochrome ingredients, the P content of the low-P ferrochrome is less than or equal to 0.02 percent, and the P content of dephosphorized molten iron is less than or equal to 0.007 percent;

the AOD adopts electrolytic manganese, low-aluminum ferrosilicon and low-Al ferroniobium, wherein the Al content of the low-aluminum ferrosilicon and low-Al ferroniobium is less than or equal to 0.1 percent, and niobium alloying is completed in the AOD stage;

the superheat degree of the tundish is 20-35 ℃, the electromagnetic stirring current intensity is 1550A-1750A, and finally, a slab with 220mm multiplied by 1260mm multiplied by 7000-8000 mm is manufactured;

step 2: hot rolling, namely producing by a process of primary slab heating, secondary slab heating, rough rolling, steckel mill rolling and coiling;

wherein the primary heating temperature of the plate blank is 1100-1140 ℃ and the heating time is 250-300 min; the secondary heating temperature of the plate blank is 1230-1250 ℃, and the heating time is 230-250min;

the thickness of the stainless steel hot rolled coil for the welding strip is 5.5mm;

step 3: cold rolling, namely, producing according to the conventional austenitic stainless steel hot annealing pickling-20 roller rolling-cold annealing pickling process, wherein when a welded strip is coiled on a hot annealing pickling line by using stainless steel, one coil is connected with a 6 m 304 stainless steel guiding strip at the head part, and the other coil is connected with the 6 m 304 stainless steel guiding strip at the tail part.