Summary of the invention:
Technical problem to be solved by this invention provides the high CSP production process for hot-galvanizing-baking hardened steel sheet of a kind of production efficiency.
The technical scheme of technical solution problem of the present invention is: a kind of CSP production process for hot-galvanizing-baking hardened steel sheet, comprise steel making working procedure, continuous casting working procedure, soaking operation, hot continuous rolling operation, coiling process, pickling and cold-rolling operation, zinc-plated operation, the chemical weight item of described baking hardened steel is: 0.055%≤C≤0.075%; Si≤0.03%; 0.25%≤Mn≤0.35%; P≤0.015%; S≤0.012%; 0.015%≤Al
s≤ 0.045%; 0.015%≤B≤0.035%; All the other are Fe and impurity element.
In soaking operation operation, soaking temperature is 1100~1150 ℃.
In the hot continuous rolling operation, 900~950 ℃ of finishing temperatures; Adopt 7 frame hot rollings, draft is F1:40~50% relatively; F2 ~ F3:30 ~ 37%; F4 ~ F5:15 ~ 25%; F6 ~ F7:10 ~ 18%.
In coiling process, adopt the multi-stage type controlled chilling, at first be cooled fast to 720~760 ℃ by finishing temperature; Naturally cooling 4~8s, curling temperature is 650~700 ℃.
In the pickling and cold-rolling operation, adopt 4 frames cold rolling, draft is STD1:30~37% relatively; STD2:35~40%; STD3:30~35%; STD4:0.1~0.5%:
In zinc-plated operation, 830~850 ℃ of continuous annealing furnace temperature; Polishing unit elongation 1.2-1.5%.
The composition of steel of the present invention is on the basis of low C steel, adopt boron alloyization, strict each alloying element content of control, the microstructure of the hot galvanizing bake hardening steel that the present invention produces is based on ferrite+a small amount of nodular troostite, also may contain tissues such as a small amount of granular bainite and a small amount of cementite simultaneously.
The present invention adopts the short flow process of CSP CSP to cooperate pickling, cold rolling, continuous annealing and hot dip galvanizing process to produce other bake hardening steel of 220MPa level.220MPa level hot galvanizing bake hardening steel product performance are: R
P0.2: 220~280MPa, R
m: 340~400MPa, A
80〉=32%, r
90〉=1.2, n
90〉=0.15, BH 〉=35.Compare with the production technique of traditional continuous casting, hot rolling flow process, because the CSP flow process is shorter, production efficiency improves greatly.
Want the present invention compared with prior art: can produce hot-galvanizing-baking hardened steel efficiently, cheaply.The hot-galvanizing-baking hardened steel performance that the present invention produces satisfies the relevant criterion requirement, can be applicable to automobile production.
Embodiment:
Non-limiting examples is as follows:
It is 1200mm that the used CSP production line of the present invention is about 400 meters, pickling and cold-rolling line length 250m, zinc-plated line length 300m, finished product volume width, thickness 0.7mm, 22.4 tons of maximum volume-weights.
The hot-galvanizing-baking hardened steel performance is tested by European standard EN 10292:2000.
Embodiment 1:
1, steel making working procedure: steel melting furnace employing capacity is 120 tons converter, and tap is 125 tons, 1655 ℃ of tapping temperatures; The molten steel that steel melting furnace is come out carries out refining in ladle refining furnace, adopt to heat up, add alloy and be adjusted to ordinary methods such as branch, calcium processing, molten steel composition weight percent after refining finishes is controlled to be: C:0.07, Si:0.02, Mn:0.28, P:0.012, S:0.002, B:0.0026, Als:0.028,1610 ℃ of liquid steel temperatures.
2, continuous casting working procedure: 35 ℃ of molten steel overheats, adopt funnel-type crystallizer, this crystallizer is a hydraulic vibration, strand pulling rate 3.5m/min, slab thickness are 70mm.
3, soaking operation: strand enters soaking pit after cooling off through secondary cooling zone, and soaking pit length 268m, strand advance 930 ℃ of furnace temperatures, 1130 ℃ of tapping temperatures, strand residence time 30min.
4, hot continuous rolling operation: after strand went out soaking pit, removal showed that oxide skin enters 7 frame hot continuous rolling units through scale breaker, and draft is F1:40% relatively; F2 ~ F3:30%; F4 ~ F5:15%; F6 ~ F7:10%.1100 ℃ of start rolling temperatures, 910 ℃ of finishing temperatures, rolling V-bar is 800m/min, hot rolling thickness is 2.7mm.
5, coiling process: above-mentioned hot-rolled sheet enters reeling machine through the laminar flow cooling, and the cooling section speed of cooling is about 35 ℃/s continuously, and coiling temperature is 690 ℃.
6, pickling and cold-rolling operation: enter pickling tank after the hot rolled coil uncoiling, pickling speed 166m/min enters 4 frame tandem mills then, and draft is STD1:30% relatively; STD2:35%; STD3:30%; STD4:0.1%; Batch after cold rolling.
7, zinc-plated operation: roll to wind off firmly and involve in, 840 ℃ of annealing temperatures, linear velocity 120m/min, polishing unit elongation 1.5% into continuous annealing furnace.
Table 1: embodiment 1 typical composition (wt., %)
C |
Si |
Mn |
P |
S |
B |
Als |
0.07 |
0.02 |
0.28 |
0.012 |
0.002 |
0.0026 |
0.028 |
Embodiment 2:
1, steel making working procedure: steel melting furnace employing capacity is 120 tons converter, and tap is 125 tons, 1655 ℃ of tapping temperatures; The molten steel that steel melting furnace is come out carries out refining in ladle refining furnace, adopt to heat up, add alloy and be adjusted to ordinary methods such as branch, calcium processing, molten steel composition weight percent after refining finishes is controlled to be: C:0.064, Si:0.02, Mn:0.29, P:0.008, S:0.0037, B:0.0031, Als:0.049,1610 ℃ of liquid steel temperatures.
2, continuous casting working procedure: 35 ℃ of molten steel overheats, adopt funnel-type crystallizer, this crystallizer is a hydraulic vibration, strand pulling rate 3.5m/min, slab thickness are 70mm.
3, soaking operation: strand enters soaking pit after cooling off through secondary cooling zone, and soaking pit length 268m, strand advance 930 ℃ of furnace temperatures, 1130 ℃ of tapping temperatures, strand residence time 30min.
4, hot continuous rolling operation: after strand went out soaking pit, removal showed that oxide skin enters 7 frame hot continuous rolling units through scale breaker, and draft is F1:40% relatively; F2 ~ F3:30%; F4 ~ F5:15%; F6 ~ F7:10%.1100 ℃ of start rolling temperatures, 910 ℃ of finishing temperatures, rolling V-bar is 800m/min, hot rolling thickness is 2.7mm.
5, coiling process: above-mentioned hot-rolled sheet enters reeling machine through the laminar flow cooling, and the cooling section speed of cooling is about 35 ℃/s continuously, and coiling temperature is 690 ℃.
6, pickling and cold-rolling operation: enter pickling tank after the hot rolled coil uncoiling, pickling speed 166m/min enters 4 frame tandem mills then, and draft is STD1:30% relatively; STD2:35%; STD3:30%; STD4:0.1%; Batch after cold rolling.
7, zinc-plated operation: roll to wind off firmly and involve in, 840 ℃ of annealing temperatures, linear velocity 120m/min, polishing unit elongation 1.5% into continuous annealing furnace.
Table 2: embodiment 2 typical compositions (wt., %)
C |
Si |
Mn |
P |
S |
B |
Als |
0.064 |
0.02 |
0.29 |
0.008 |
0.0037 |
0.0031 |
0.049 |
Embodiment 3:
1, steel making working procedure: steel melting furnace employing capacity is 120 tons converter, and tap is 125 tons, 1655 ℃ of tapping temperatures; The molten steel that steel melting furnace is come out carries out refining in ladle refining furnace, adopt to heat up, add alloy and be adjusted to ordinary methods such as branch, calcium processing, molten steel composition weight percent after refining finishes is controlled to be: C:0.074, Si:0.03, Mn:0.32, P:0.0095, S:0.002, B:0.0033, Als:0.052,1610 ℃ of liquid steel temperatures.
2, continuous casting working procedure: 35 ℃ of molten steel overheats, adopt funnel-type crystallizer, this crystallizer is a hydraulic vibration, strand pulling rate 3.5m/min, slab thickness are 70mm.
3, soaking operation: strand enters soaking pit after cooling off through secondary cooling zone, and soaking pit length 268m, strand advance 930 ℃ of furnace temperatures, 1130 ℃ of tapping temperatures, strand residence time 30min.
4, hot continuous rolling operation: after strand went out soaking pit, removal showed that oxide skin enters 7 frame hot continuous rolling units through scale breaker, and draft is F1:40% relatively; F2 ~ F3:30%; F4 ~ F5:15%; F6 ~ F7:10%.1100 ℃ of start rolling temperatures, 910 ℃ of finishing temperatures, rolling V-bar is 800m/min, hot rolling thickness is 2.7mm.
5, coiling process: above-mentioned hot-rolled sheet enters reeling machine through the laminar flow cooling, and the cooling section speed of cooling is about 35 ℃/s continuously, and coiling temperature is 690 ℃.
6, pickling and cold-rolling operation: enter pickling tank after the hot rolled coil uncoiling, pickling speed 166m/min enters 4 frame tandem mills then, and draft is STD1:30% relatively; STD2:35%; STD3:30%; STD4:0.1%; Batch after cold rolling.
7, zinc-plated operation: roll to wind off firmly and involve in, 840 ℃ of annealing temperatures, linear velocity 120m/min, polishing unit elongation 1.5% into continuous annealing furnace.
Table 3: embodiment 3 typical compositions (wt., %)
C |
Si |
Mn |
P |
S |
B |
Als |
0.074 |
0.03 |
0.32 |
0.0095 |
0.002 |
0.0033 |
0.052 |
Embodiment 4:
1, steel making working procedure: steel melting furnace employing capacity is 120 tons converter, and tap is 125 tons, 1655 ℃ of tapping temperatures; The molten steel that steel melting furnace is come out carries out refining in ladle refining furnace, adopt to heat up, add alloy and be adjusted to ordinary methods such as branch, calcium processing, molten steel composition weight percent after refining finishes is controlled to be: C:0.069, Si:0.03, Mn:0.30, P:0.011, S:0.0037, B:0.0026, Als:0.036,1610 ℃ of liquid steel temperatures.
2, continuous casting working procedure: 35 ℃ of molten steel overheats, adopt funnel-type crystallizer, this crystallizer is a hydraulic vibration, strand pulling rate 3.5m/min, slab thickness are 70mm.
3, soaking operation: strand enters soaking pit after cooling off through secondary cooling zone, and soaking pit length 268m, strand advance 930 ℃ of furnace temperatures, 1130 ℃ of tapping temperatures, strand residence time 30min.
4, hot continuous rolling operation: after strand went out soaking pit, removal showed that oxide skin enters 7 frame hot continuous rolling units through scale breaker, and draft is F1:40% relatively; F2 ~ F3:30%; F4 ~ F5:15%; F6 ~ F7:10%.1100 ℃ of start rolling temperatures, 910 ℃ of finishing temperatures, rolling V-bar is 800m/min, hot rolling thickness is 2.7mm.
5, coiling process: above-mentioned hot-rolled sheet enters reeling machine through the laminar flow cooling, and the cooling section speed of cooling is about 35 ℃/s continuously, and coiling temperature is 690 ℃.
6, pickling and cold-rolling operation: enter pickling tank after the hot rolled coil uncoiling, pickling speed 166m/min enters 4 frame tandem mills then, and draft is STD1:30% relatively; STD2:35%; STD3:30%; STD4:0.1%; Batch after cold rolling.
7, zinc-plated operation: roll to wind off firmly and involve in, 840 ℃ of annealing temperatures, linear velocity 120m/min, polishing unit elongation 1.5% into continuous annealing furnace.
Table 4: embodiment 4 typical compositions (wt., %)
C |
Si |
Mn |
P |
S |
B |
Als |
0.069 |
0.03 |
0.3 |
0.011 |
0.0037 |
0.0026 |
0.036 |
The hot-galvanizing-baking hardened steel typical case performance of the production of embodiment 1-4 is as shown in table 5:
Table 5:
Sequence number |
R
p0.2/MPa
|
R
m/MPa
|
A/% |
n
90 |
r
90 |
BH/MPa |
Embodiment 1 |
230 |
370 |
33.5 |
0.194 |
1.44 |
55 |
Embodiment 2 |
225 |
365 |
32.0 |
0.195 |
1.33 |
55 |
Embodiment 3 |
230 |
370 |
33.5 |
0.193 |
1.40 |
35 |
Embodiment 4 |
230 |
375 |
37.0 |
0.192 |
1.30 |
65 |