CN113996657B - Hot rolling process for preventing edge crack of low-chromium ferrite stainless steel - Google Patents
Hot rolling process for preventing edge crack of low-chromium ferrite stainless steel Download PDFInfo
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- 238000005098 hot rolling Methods 0.000 title claims abstract description 67
- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 48
- 239000011651 chromium Substances 0.000 title claims abstract description 47
- 229910052804 chromium Inorganic materials 0.000 title claims abstract description 45
- 239000010935 stainless steel Substances 0.000 title claims abstract description 32
- 229910000859 α-Fe Inorganic materials 0.000 title claims abstract description 32
- 238000005096 rolling process Methods 0.000 claims abstract description 186
- 238000010438 heat treatment Methods 0.000 claims abstract description 32
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 24
- 239000010959 steel Substances 0.000 claims abstract description 24
- 238000005336 cracking Methods 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 16
- 238000009749 continuous casting Methods 0.000 claims abstract description 13
- 238000005266 casting Methods 0.000 claims abstract description 9
- 239000000126 substance Substances 0.000 claims description 8
- 239000012535 impurity Substances 0.000 claims description 2
- 229910001566 austenite Inorganic materials 0.000 description 9
- 239000000203 mixture Substances 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 230000002441 reversible effect Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000005501 phase interface Effects 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/004—Heating the product
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B2015/0057—Coiling the rolled product
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- Engineering & Computer Science (AREA)
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- Metal Rolling (AREA)
Abstract
A hot rolling process for preventing edge cracking of low-chromium ferrite stainless steel belongs to the technical field of rolling processes and solves the technical problems that the existing low-chromium ferrite stainless steel is easy to cause edge cracking in the rolling process. The invention is realized by the following technical scheme: a hot rolling process for preventing edge cracking of low-chromium ferritic stainless steel comprises the following process steps: 1) Heating: placing the low-chromium ferrite stainless steel continuous casting slab into a heating furnace to heat to 1150-1200 ℃ before hot rolling, and then preserving heat, wherein the heating speed of the heating furnace is 90-100 ℃/h, and the preserving heat time T= (0.9-1.2) is multiplied by the thickness of a casting blank; 2) And (3) hot rolling: the rolling parameters are designed according to the requirement and hot rolling is carried out, and the deformation of the hot rolling pass is smaller than the critical deformationFThe method comprises the steps of carrying out a first treatment on the surface of the 3) And (3) coiling: and after rolling, coiling the steel strip into coils at 720-750 ℃. Compared with the prior art, the invention has the advantages of simple operation, wide application range and the like.
Description
Technical Field
The invention belongs to the technical field of rolling processes, and particularly relates to a hot rolling process for preventing low-chromium ferrite stainless steel from edge cracking.
Background
The low-chromium ferrite stainless steel is nickel-free or nickel-less economic stainless steel and has good local corrosion resistance such as stress corrosion resistance, pitting corrosion resistance, crevice corrosion resistance and the like. In addition, the low-chromium ferrite stainless steel has higher strength, good bending forming and welding performance, low cold work hardening tendency, large heat conductivity coefficient and small thermal expansion coefficient, and is widely applied to the fields of petrifaction, traffic, construction, household appliances and the like. However, such stainless steel has a two-phase structure of austenite and ferrite at high temperature due to a low chromium content, and is susceptible to edge cracking due to stress concentration at the phase interface during hot rolling due to the difference in deformation characteristics between austenite and ferrite. The existence of edge cracks not only affects the quality and the yield of products, but also sometimes causes equipment damage, interrupts production, and brings great economic loss for enterprises.
Aiming at the problem of edge cracking of low-chromium ferrite stainless steel caused by thermal deformation mismatch of a dual-phase structure, a control method for avoiding hot rolling edge cracking of low-chromium ferrite stainless steel is disclosed in a patent document with the application number of CN 103510022A. The method has the core ideas that the phase ratio of austenite to ferrite is optimized through component control, the austenite high-temperature transformation point of the material is raised to be higher than 1120 ℃, the material has a single austenite phase region in the temperature range of 860-1120 ℃, and hot rolling is carried out in the temperature range.
Although the method achieves the aim of reducing edge cracking by controlling the components of the low-chromium ferrite stainless steel and avoiding hot rolling deformation in a two-phase region, the requirements on the components of the steel are high, particularly the low-chromium ferrite stainless steel cannot meet the requirements, and the low-chromium ferrite stainless steel has single austenite structure in the temperature range of 860-1120 ℃. For example, the above method has a limitation because 0Cr13Al, 06Cr11Ti, 022Cr11Ti and the like in the standard "GB/T20878 stainless steel and heat-resistant steel brands and chemical compositions" of chinese stainless steel undergo a duplex region of ferrite and austenite during hot rolling because the content of austenite forming elements is relatively low, and it is difficult to satisfy the requirement of hot rolling in a single austenite phase region.
Disclosure of Invention
In order to overcome the defects of the prior art and solve the technical problems that the existing low-chromium ferrite stainless steel is easy to generate edge cracking phenomenon and the like in the rolling process, the invention provides a hot rolling process for preventing the edge cracking of the low-chromium ferrite stainless steel.
The invention is realized by the following technical scheme.
A hot rolling process for preventing edge cracking of low-chromium ferritic stainless steel comprises the following process steps:
1) Heating: placing the low-chromium ferrite stainless steel continuous casting slab into a heating furnace to heat to 1150-1200 ℃ before hot rolling, and then preserving heat, wherein the heating speed of the heating furnace is 90-100 ℃/h, and the preserving heat time T (min) = (0.9-1.2) is multiplied by the thickness (mm) of the casting blank;
2) And (3) hot rolling: the rolling parameters are designed according to the requirements, and hot rolling is carried out, wherein the deformation of the hot rolling pass is smaller than the critical deformation F;
the critical deformation amount F (%) = 50.80-30.92/(1+e) M )；
Wherein: m=0.024T-0.59C-23.10,
wherein: t is the hot rolling temperature (DEG C),
wherein: delta = 3cr+4si+3.5al+1.5ti+nb-2.5Ni-80 (c+n) -1.2 (mn+cu) -15;
3) And (3) coiling: after rolling, coiling the steel strip into coils at 720-750 ℃.
Further, in the hot rolling process, when the thickness of the low-chromium ferritic stainless steel strip is 5mm or less, the hot rolling pass deformation amount < (critical deformation amount F-2%).
Further, the deformation amount value range of the first pass is as follows: 15% -20%; the deformation measuring value range of the second pass is as follows: 20-35%; the third deformation measuring range is as follows: 20-35%; the three-time accumulated deformation is more than or equal to 50%; the interval time between hot rolling passes is: 15 s-25 s.
Further, the low-chromium ferritic stainless steel comprises the following chemical components in percentage by mass: 0< C.ltoreq.0.08%, 0< Si.ltoreq.1.0%, 0< Mn.ltoreq.2.0%, 0<P.ltoreq.0.045%, 0<S.ltoreq.0.045%, 0< N.ltoreq.0.03%, 10.5< Cr.ltoreq.15%, 0< Ni.ltoreq.1.0%, 0< Cu.ltoreq.2.0%, 0< Al.ltoreq.0.3%, 0< Ti.ltoreq.2.0%, 0< Nb.ltoreq.1.5%, the balance being Fe and unavoidable impurities.
The invention can solve the problem of hot rolling edge crack of the low-chromium ferrite stainless steel only by controlling the hot rolling process, does not have excessive requirements on the chemical components of the steel, has stronger applicability in actual industrial production, and is more beneficial to industrialized popularization. Compared with the prior art, the invention has the advantages of simple operation, wide application range and the like.
Detailed Description
The present invention will be described in further detail with reference to examples.
Example 1
A hot rolling process for preventing edge cracking of low-chromium ferritic stainless steel comprises the following process steps:
1) Heating: placing the low-chromium ferrite stainless steel continuous casting slab into a heating furnace to heat to 1150 ℃ before hot rolling, wherein the heating speed of the heating furnace is 90-100 ℃/h, and the heat preservation time is 210min; the thickness specification of the low-chromium ferrite stainless steel continuous casting slab is 200mm;
2) And (3) hot rolling: the rolling parameters are designed according to the requirements, and hot rolling is carried out, wherein the deformation of the hot rolling pass is smaller than the critical deformation F;
the critical deformation amount F (%) = 50.80-30.92/(1+e) M )；
Wherein: m=0.024T-0.59C-23.10,
wherein: t is the hot rolling temperature (DEG C),
wherein: delta = 3cr+4si+3.5al+1.5ti+nb-2.5Ni-80 (c+n) -1.2 (mn+cu) -15;
the rolling parameters are set as follows: and hot rolling for 10 times to obtain a steel coil with the thickness specification of 6mm, wherein the first 5 times of hot rolling are single-frame reversible rolling and the second 5 times are multi-frame continuous rolling. The method comprises the following steps:
the 1 st pass rolling temperature is 1050 ℃, the thickness before rolling is 200mm, the thickness after rolling is 162mm, the pass deformation is 19%, and the pass deformation is less than the critical pass deformation F=46.4%.
The rolling temperature of the 2 nd pass is 1047 ℃, the thickness before rolling is 162mm, the thickness after rolling is 120mm, the pass deformation is 26% and less than the critical pass deformation F=46.1%, and the time interval between the rolling and the last rolling is 15s.
The rolling temperature of the 3 rd pass is 1035 ℃, the thickness before rolling is 120mm, the thickness after rolling is 85mm, the pass deformation is 29%, the pass deformation is less than the critical pass deformation F=44.9%, the time interval between the pass rolling and the last pass rolling is 20s, and the accumulated deformation of the last three passes is (200 mm-85 mm)/200 mm=57.5%.
The 4 th pass rolling temperature is 1020 ℃, the thickness before rolling is 85mm, the thickness after rolling is 56mm, the pass deformation is 34% and is less than the critical pass deformation F=42.9%.
The 5 th pass rolling temperature is 1000 ℃, the thickness before rolling is 56mm, the thickness after rolling is 34mm, the pass deformation is 37.5%, and the pass deformation is less than the critical pass deformation F=39.8%.
The 6 th pass rolling temperature is 980 ℃, the thickness before rolling is 34mm, the thickness after rolling is 23mm, the pass deformation is 32.4%, and the pass deformation is less than the critical pass deformation F=36.2%.
The 7 th pass rolling temperature is 970 ℃, the thickness before rolling is 23mm, the thickness after rolling is 16mm, the pass deformation is 30.4%, and the pass deformation is less than the critical pass deformation F=34.4%.
The 8 th pass rolling temperature is 961 ℃, the thickness before rolling is 16mm, the thickness after rolling is 11mm, the pass deformation is 30.4%, and the pass deformation is less than the critical pass deformation F=32.7%.
The 9 th pass rolling temperature 951 ℃, the thickness before rolling is 11mm, the thickness after rolling is 7.8mm, the pass deformation is 29.1%, and the pass deformation is less than the critical pass deformation F=31.0%.
The 10 th pass rolling temperature is 925 ℃, the thickness before rolling is 7.8mm, the thickness after rolling is 6.1mm, the pass deformation is 23.1%, and the pass deformation is less than critical pass deformation F=27.0%.
3) And (3) coiling: after rolling, the steel strip is coiled into a coil at 750 ℃, and the two side edges of the steel coil have no cracks.
The chemical composition of the low-chromium ferritic stainless steel is shown in table 1.
Example 2
A hot rolling process for preventing edge cracking of low-chromium ferritic stainless steel comprises the following process steps:
1) Heating: placing the low-chromium ferrite stainless steel continuous casting slab into a heating furnace to be heated to 1200 ℃ before hot rolling, and preserving heat, wherein the heating speed of the heating furnace is 90-100 ℃/h, and the preserving heat time is 183min; the thickness specification of the low-chromium ferrite stainless steel continuous casting slab is 200mm;
2) And (3) hot rolling: the rolling parameters are designed according to the requirements, and hot rolling is carried out, wherein the deformation of the hot rolling pass is smaller than the critical deformation F;
the critical deformation amount F (%) = 50.80-30.92/(1+e) M )；
Wherein: m=0.024T-0.59C-23.10,
wherein: t is the hot rolling temperature (DEG C),
wherein: delta = 3cr+4si+3.5al+1.5ti+nb-2.5Ni-80 (c+n) -1.2 (mn+cu) -15;
the rolling parameters are set as follows: carrying out 12-pass hot rolling to obtain a steel coil with the thickness specification of 3.5 mm; wherein the first 5 times of hot rolling are single-frame reversible rolling, and the last 7 times are multi-frame continuous rolling. The method comprises the following steps:
the 1 st pass rolling temperature is 1100 ℃, the thickness before rolling is 200mm, the thickness after rolling is 166mm, the pass deformation is 17%, and the pass deformation is less than the critical pass deformation F=49.3%.
The rolling temperature of the 2 nd pass is 1093 ℃, the thickness before rolling is 166mm, the thickness after rolling is 116mm, the pass deformation is 30%, the pass deformation is less than the critical pass deformation F=49.0%, and the time interval between the rolling and the last rolling is 15s.
The 3 rd pass rolling temperature is 1080 ℃, the thickness before rolling is 116mm, the thickness after rolling is 78mm, the pass deformation amount is 32.8%, the critical pass deformation amount F=48.4%, the time interval between the rolling and the last pass is 18s, and the accumulated deformation amount of the last three times is (200 mm-78 mm)/200 mm=61.5%.
The 4 th pass rolling temperature is 1065 ℃, the thickness before rolling is 78mm, the thickness after rolling is 53mm, the pass deformation is 32%, and the pass deformation is less than the critical pass deformation F=47.5%.
The 5 th pass rolling temperature is 1040 ℃, the thickness before rolling is 53mm, the thickness after rolling is 33mm, the pass deformation is 37.7%, and the pass deformation is less than the critical pass deformation F=45%.
The 6 th pass rolling temperature is 1000 ℃, the thickness before rolling is 33mm, the thickness after rolling is 21mm, the pass deformation is 36.4%, and the pass deformation is less than the critical pass deformation F=39.5%.
The 7 th pass rolling temperature is 988 ℃, the thickness before rolling is 21mm, the thickness after rolling is 14.5mm, the pass deformation is 31%, and the pass deformation is less than the critical pass deformation F=37.4%.
The 8 th pass rolling temperature is 973 ℃, the thickness before rolling is 14.5mm, the thickness after rolling is 10mm, the pass deformation is 31%, and the pass deformation is less than the critical pass deformation F=34.6%.
The 9 th pass rolling temperature is 956 ℃, the thickness before rolling is 10mm, the thickness after rolling is 7.2mm, the pass deformation is 28%, and the pass deformation is less than the critical pass deformation F=31.6%.
The 10 th pass rolling temperature 938 ℃, the thickness before rolling is 7.2mm, the thickness after rolling is 5.3mm, the pass deformation is 26.4%, and the critical pass deformation F=28.6%.
The 11 th pass rolling temperature is 920 ℃, the thickness before rolling is 5.3mm, the thickness after rolling is 4.2mm, the pass deformation is 21%, and the pass deformation is less than the critical pass deformation F=25.9%.
The 12 th pass rolling temperature is 901 ℃, the thickness before rolling is 4.2mm, the thickness after rolling is 3.5mm, the pass deformation is 16.7%, and the pass deformation is less than the critical pass deformation F=24.3%; the thickness of the steel plate is less than 5mm when in rolling, the required pass deformation is less than the critical pass deformation F-2% = 20.3%, and 16.7% is less than 20.3%, so that the requirements are met.
3) And (3) coiling: after rolling, the steel strip is coiled into a coil at 720 ℃, and the two side edges of the steel coil have no cracks.
The chemical composition of the low-chromium ferritic stainless steel is shown in table 1.
Example 3
A hot rolling process for preventing edge cracking of low-chromium ferritic stainless steel comprises the following process steps:
1) Heating: placing the low-chromium ferrite stainless steel continuous casting slab into a heating furnace to be heated to 1180 ℃ before hot rolling, and then preserving heat, wherein the heating speed of the heating furnace is 90-100 ℃/h, and the preserving heat time is 200min; the thickness specification of the low-chromium ferrite stainless steel continuous casting slab is 180mm;
2) And (3) hot rolling: the rolling parameters are designed according to the requirements, and hot rolling is carried out, wherein the deformation of the hot rolling pass is smaller than the critical deformation F;
the critical deformation amount F (%) = 50.80-30.92/(1+e) M )；
Wherein: m=0.024T-0.59C-23.10,
wherein: t is the hot rolling temperature (DEG C),
wherein: delta = 3cr+4si+3.5al+1.5ti+nb-2.5Ni-80 (c+n) -1.2 (mn+cu) -15;
the rolling parameters are set as follows: carrying out 12-pass hot rolling to obtain a steel coil with the thickness specification of 2.8 mm; wherein the first 5 times of hot rolling are single-frame reversible rolling, and the last 7 times are multi-frame continuous rolling. The method comprises the following steps:
the 1 st pass rolling temperature is 1080 ℃, the thickness before rolling is 180mm, the thickness after rolling is 153mm, the pass deformation is 15%, and the critical pass deformation F=49.3%.
The rolling temperature of the 2 nd pass is 1071 ℃, the thickness before rolling is 153mm, the thickness after rolling is 118mm, the pass deformation is 23%, the pass deformation is less than the critical pass deformation F=48.2%, and the time interval between the rolling and the last rolling is 16s.
The rolling temperature of the 3 rd pass is 1060 ℃, the thickness before rolling is 118mm, the thickness after rolling is 83mm, the pass deformation is 29.7%, the pass deformation is less than the critical pass deformation F=47.4%, the time interval between the rolling and the last rolling is 23s, and the accumulated deformation of the last three times is (180 mm-83 mm)/180 mm=53.9%.
The 4 th pass rolling temperature is 1045 ℃, the thickness before rolling is 83mm, the thickness after rolling is 51.5mm, the pass deformation is 38%, and the pass deformation is less than the critical pass deformation F=46.1%.
The 5 th pass rolling temperature is 1027 ℃, the thickness before rolling is 51.5mm, the thickness after rolling is 33mm, the pass deformation is 36%, and the pass deformation is less than the critical pass deformation F=44.2%.
The 6 th pass rolling temperature is 990 ℃, the thickness before rolling is 33mm, the thickness after rolling is 21.5mm, the pass deformation is 36.4%, and the pass deformation is less than the critical pass deformation F=38.5%.
The 7 th pass rolling temperature is 983 ℃, the thickness before rolling is 21mm, the thickness after rolling is 14mm, the pass deformation is 33%, and the pass deformation is less than the critical pass deformation F=37.2%.
The 8 th pass rolling temperature is 975 ℃, the thickness before rolling is 14mm, the thickness after rolling is 9.8mm, the pass deformation is 31%, and the pass deformation is less than the critical pass deformation F=35.7%.
The 9 th pass rolling temperature is 966 ℃, the thickness before rolling is 9.8mm, the thickness after rolling is 6.6mm, the pass deformation is 32.7%, and the pass deformation is less than critical pass deformation F=34%.
The 10 th pass rolling temperature is 953 ℃, the thickness before rolling is 5.3mm, the thickness after rolling is 3.8mm, the pass deformation is 28%, and the pass deformation is less than the critical pass deformation F=31.7%.
The 11 th pass rolling temperature is 935 ℃, the thickness before rolling is 3.8mm, the thickness after rolling is 3.2mm, the pass deformation is 16%, the pass deformation is smaller than the critical pass deformation F=28.8%, the required pass deformation is smaller than the critical pass deformation F-2% =26.8% and the 16% is smaller than 26.8% because the thickness of the steel plate is smaller than 5mm during rolling, and the requirements are met.
The 12 th pass rolling temperature is 913 ℃, the thickness before rolling is 3.2mm, the thickness after rolling is 2.8mm, the pass deformation is 12.5%, the pass deformation is less than the critical pass deformation F=25.8%, the required pass deformation is less than the critical pass deformation F-2% =23.8% and the 12.5% is less than 23.8% because the thickness of the steel plate is less than 5mm during rolling, and the requirements are met.
3) And (3) coiling: after rolling, the steel strip is coiled into a coil at 728 ℃, and the two side edges of the steel coil have no cracks.
The chemical composition of the low-chromium ferritic stainless steel is shown in table 1.
Comparative example 1:
a piece of low-chromium ferritic stainless steel continuous casting slab of the same furnace steel as in example 1 was charged into the same heating furnace and heated in the same manner. After heating, it was subjected to hot rolling as follows:
the rolling temperature of the 1 st pass is 1053 ℃, the thickness before rolling is 200mm, the thickness after rolling is 163mm, the pass deformation is 18.5% and is smaller than the critical pass deformation F=46.4%, and no edge crack occurs.
The rolling temperature of the 2 nd pass is 1049 ℃, the thickness before rolling is 163mm, the thickness after rolling is 122mm, the pass deformation is 25%, the pass deformation is less than the critical pass deformation F=46.7%, the time interval between the rolling and the last rolling is 16s, and no edge crack occurs.
The rolling temperature of the 3 rd pass is 1036 ℃, the thickness before rolling is 122mm, the thickness after rolling is 87mm, the pass deformation is 28.7%, the pass deformation is less than the critical pass deformation F=45.0%, the time interval between the pass rolling and the last pass rolling is 21s, the accumulated deformation of the last three times is (200 mm-85 mm)/200 mm=56.5%, and no edge crack occurs.
The 4 th pass rolling temperature is 1018 ℃, the thickness before rolling is 87mm, the thickness after rolling is 55mm, the pass deformation is 36.8%, the pass deformation is less than the critical pass deformation F=42.7%, and no edge crack occurs.
The 5 th pass rolling temperature is 990 ℃, the thickness before rolling is 55mm, the thickness after rolling is 33mm, the pass deformation is 40% and is greater than the critical pass deformation F=38%, and cracks appear at the edge.
The 6 th pass rolling temperature is 980 ℃, the thickness before rolling is 33mm, the thickness after rolling is 20mm, the pass deformation is 39.4%, the pass deformation is greater than the critical pass deformation F=36%, the edge crack is deepened, and the rolling is terminated.
Comparative example 2:
a piece of low-chromium ferritic stainless steel continuous casting slab of the same furnace steel as in example 1 was charged into the same heating furnace and heated in the same manner. After heating, it was subjected to hot rolling as follows:
the rolling temperature of the first pass is 1053 ℃, the thickness before rolling is 200mm, the thickness after rolling is 150mm, the pass deformation is 25%, the upper limit of the first pass deformation is exceeded by 20%, cracks appear at the edge of a casting blank, and rolling is stopped.
Comparative example 3:
a piece of low-chromium ferrite stainless steel continuous casting slab which is the same as the steel in the embodiment 1 is put into the same heating furnace, heated to 1250 ℃ at the heating speed of 90-100 ℃/h, and then is insulated for 180 minutes, so that the surface of the steel billet is seriously oxidized. According to the rolling method of example 1, the casting blank is heated to a high temperature, the crystal grains are coarsened, the thermoplasticity is deteriorated, and cracks appear at the edge of the casting blank during the second pass rolling, and the rolling is terminated.
Comparative example 4:
a piece of low-chromium ferritic stainless steel continuous casting slab of the same furnace steel as in example 3 was charged into the same heating furnace and heated in the same manner. After heating, it was subjected to hot rolling as follows:
the rolling temperature of the 1 st pass is 1083 ℃, the thickness before rolling is 180mm, the thickness after rolling is 150mm, the pass deformation is 16.7%, the pass deformation is less than the critical pass deformation F=48.7%, and no edge crack occurs.
The rolling temperature of the 2 nd pass is 1075 ℃, the thickness before rolling is 150mm, the thickness after rolling is 120mm, the pass deformation is 20%, the pass deformation is less than the critical pass deformation F=48.3%, the time interval between the pass deformation and the last pass rolling is 5s, the deformed metal is not effectively recovered and recrystallized due to the shorter rolling time interval, and microcracks appear on the edge part of the casting blank locally.
The rolling temperature of the 3 rd pass is 1069 ℃, the thickness before rolling is 120mm, the thickness after rolling is 84mm, the pass deformation is 30%, the pass deformation is smaller than the critical pass deformation F=45.0%, the rolling interval time is 4s compared with the previous rolling interval time, similarly, the deformed metal is not effectively recovered and recrystallized due to the short rolling interval time, the crack of the edge part of a casting blank deepens, and the rolling is stopped.
Table 1 chemical composition units of the steels of examples 1-3: w.t%
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present invention should be included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (4)
1. A hot rolling process for preventing edge cracking of low-chromium ferrite stainless steel is characterized in that: the method comprises the following process steps:
1) Heating: placing the low-chromium ferrite stainless steel continuous casting slab into a heating furnace to heat to 1150-1200 ℃ before hot rolling, and then preserving heat, wherein the heating speed of the heating furnace is 90-100 ℃/h, the preserving heat time T= (0.9-1.2) is multiplied by the thickness of a casting blank, wherein the preserving heat time T is in min, and the thickness of the casting blank is in mm;
2) And (3) hot rolling: the rolling parameters are designed according to the requirements, and hot rolling is carried out, wherein the deformation of the hot rolling pass is smaller than the critical deformation F;
the critical deformation F= 50.80-30.92/(1+e) M ) Wherein the critical deformation amount F is in units of;
wherein: m=0.024T-0.59C-23.10;
wherein: t is the hot rolling temperature, the unit of the hot rolling temperature T is that,
wherein: delta = 3cr+4si+3.5al+1.5ti+nb-2.5Ni-80 (c+n) -1.2 (mn+cu) -15;
3) And (3) coiling: after rolling, coiling the steel strip into coils at 720-750 ℃.
2. The hot rolling process for preventing edge cracking of low-chromium ferritic stainless steel according to claim 1, wherein: in the hot rolling process, when the thickness of the low-chromium ferrite stainless steel strip is less than or equal to 5mm, the hot rolling pass deformation is < (critical deformation F-2%).
3. A hot rolling process for preventing edge cracking of low-chromium ferritic stainless steel according to claim 1 or 2, characterized in that: the deformation value range of the first pass is as follows: 15% -20%; the deformation measuring value range of the second pass is as follows: 20-35%; the third deformation measuring range is as follows: 20-35%; the three-time accumulated deformation is more than or equal to 50%; the interval time between hot rolling passes is: 15 s-25 s.
4. The hot rolling process for preventing edge cracking of low-chromium ferritic stainless steel according to claim 1, wherein: the low-chromium ferrite stainless steel comprises the following chemical components in percentage by mass: 0< C.ltoreq.0.08%, 0< Si.ltoreq.1.0%, 0< Mn.ltoreq.2.0%, 0<P.ltoreq.0.045%, 0<S.ltoreq.0.045%, 0< N.ltoreq.0.03%, 10.5< Cr.ltoreq.15%, 0< Ni.ltoreq.1.0%, 0< Cu.ltoreq.2.0%, 0< Al.ltoreq.0.3%, 0< Ti.ltoreq.2.0%, 0< Nb.ltoreq.1.5%, the balance being Fe and unavoidable impurities.
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| KR20010047965A (en) * | 1999-11-24 | 2001-06-15 | 이구택 | Method for plate rolling dual phase stainless steel |
| CN101607266A (en) * | 2009-07-20 | 2009-12-23 | 山东泰山钢铁集团有限公司 | A kind of steekle mill that is applicable to is produced the method for ferritic stainless steel hot-rolling steel band |
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