Continuous annealing method for low coercive force cold-rolled electromagnetic pure iron plate and strip

Abstract

A continuous annealing method for low coercive force cold-rolled electromagnetic pure iron plate and strip. Control parameters of each stages in a continuous annealing process are as follows: 750-850 C. at a heating stage; 750-850 C. at a soaking stage, the soaking time is 100-150 s; an outlet temperature of 575-675 C. at a slow-cooling stage, the cooling speed in slow-cooling stage is 2.5-10 C./s; an outlet temperature of 380-420 C. at a fast-cooling stage, the cooling speed of the fast-cooling stage is 15-25 C./s; and 270-310 C. at an overaging stage. The annealing medium is a non-oxidizing atmosphere composed of H.sub.2 and N.sub.2. After annealing, the cold-rolled electromagnetic pure iron plate and strip is leveled and pressed such that the leveling elongation rate of the plate and strip is controlled within the range of 0.20.1%. The process of the continuous annealing method is simple, and the produced cold-rolled electromagnetic pure iron plate and strip can achieve an overall performance of low coercive force and good formability without further magnetic annealing.

Claims

1. A continuous annealing method for low coercive force cold-rolled electromagnetic pure iron sheet, wherein control parameters of each stage in a continuous annealing process are as follows: 750-850 C. at a heating stage; 750-850 C. at a soaking stage, with a soaking time being 100-150 s; an outlet temperature of 575-675 C. at a slow-cooling stage, with a cooling speed in the slow-cooling stage being 2.5-10 C./s; an outlet temperature of 380-420 C. at a fast-cooling stage, with a cooling speed of the fast-cooling stage being 15-25 C./s; and 270-310 C. at an overaging stage; an annealing medium is a non-oxidizing atmosphere composed of H.sub.2 and N.sub.2; after annealing, the cold-rolled electromagnetic pure iron sheet strip is leveled and pressed such that a leveling elongation rate of the sheet strip is controlled within a range of 0.20.1%.

2. The continuous annealing method for low coercive force cold-rolled electromagnetic pure iron sheet strip according to claim 1, wherein a thickness of the said cold-rolled electromagnetic pure iron sheet strip is 0.5-3.0 mm.

3. The continuous annealing method for low coercive force cold-rolled electromagnetic pure iron sheet strip according to claim 1, wherein a percent composition by mass of the elements of the said cold-rolled electromagnetic pure iron sheet strip is: C0.005%, Si0.1%, Mn=0.1-0.5%, P0.02%, S0.003%, Al0.005% or Al=0.1-1.5%, B0.007%, [N]0.005%, [O]0.02%, and the rest is Fe and unavoidable impurities.

4. The continuous annealing method for low coercive force cold-rolled electromagnetic pure iron sheet strip according to claim 3, wherein the said cold-rolled electromagnetic pure iron sheet strip after annealing has a coercive force of 60-100 A/m, a yield strength of not less than 120 MPa, a elongation of not less than 35%.

5. The continuous annealing method for low coercive force cold-rolled electromagnetic pure iron sheet strip according to claim 3, wherein hot-rolled processing parameters of the said cold-rolled electromagnetic pure iron sheet strip are: heating temperature of 1000-1200 C.; final rolling temperature of 750-900 C.; reeling temperature of 550-720 C.; cold-rolled reduction rate of within 30-55%.

Description

DETAILED DESCRIPTION

Example 1

(1) Components: the percent composition by mass of the elements of the strip steel is shown in Table 2, and the rest is Fe and unavoidable impurities. The strip thickness is 1.20.04 mm.

(2) TABLE-US-00002 TABLE 2 The mass percentages of the chemical composition of the strip steel of Example 1 (unit: %) C Si Mn P S Al B N O 0.0021 0.089 0.27 0.016 0.003 0.001 0.0001 0.002 0.018

(3) Process: parameters in hot-rolled process: heating temperature 1150 C.; final rolling temperature 850 C.; reeling temperature 550 C.; cold-rolled reduction rate 50%.

(4) The specific processing parameters according to the annealing method of present invention are: 83020 C. at a heating stage; 83020 C. at a soaking stage, the soaking time is 140 s; an outlet temperature of 675 C. at a slow-cooling stage, the cooling speed in slow-cooling stage is 5 C./s; an outlet temperature of 400 C. at a fast-cooling stage, the cooling speed of the fast-cooling stage is 25 C./s; and 300 C. at an overaging stage; the annealing medium is a non-oxidizing atmosphere composed of H.sub.2 and N.sub.2. The leveling elongation rate of the annealed sheet strip is controlled within the range of 0.20.1%.

(5) Implementation results: coercive force He of continuous annealing of cold-rolled electromagnetic pure iron sheet strip: 71 A/m, yield strength: 159 Mpa, elongation: 53.5%. It has good overall performance.

Example 2

(6) Components: the percent composition by mass of the elements of the strip steel is shown in Table 3, and the rest is Fe and unavoidable impurities. The strip thickness is 2.00.04 mm.

(7) TABLE-US-00003 TABLE 3 The mass percentages of the chemical composition of the strip steel of Example 2 (unit: %) C Si Mn P S Al B N O 0.0019 0.003 0.18 0.019 0.003 0.55 0.0001 0.0019 0.005

(8) Process: parameters in hot-rolled process: heating temperature 1150 C.; final rolling temperature 870 C.; reeling temperature 650 C.; cold-rolled reduction rate 45%.

(9) The specific processing parameters according to the annealing method of present invention are: 83020 C. at a heating stage; 83020 C. at a soaking stage, the soaking time is 130 s; an outlet temperature of 675 C. at a slow-cooling stage, the cooling speed in slow-cooling stage is 5 C./s; an outlet temperature of 400 C. at a fast-cooling stage, the cooling speed of the fast-cooling stage is 25 C./s; and 300 C. at an overaging stage; the annealing medium is a non-oxidizing atmosphere composed of H.sub.2 and N.sub.2. The leveling elongation rate of the annealed sheet strip is controlled within the range of 0.20.1%.

(10) Implementation results: coercive force He of continuous annealing of cold-rolled electromagnetic pure iron sheet strip: 65 A/m, yield strength: 155 Mpa, elongation: 55%. It has a good overall performance.

Example 3

(11) Components: the percent composition by mass of the elements of the strip steel is shown in Table 4, and the rest is Fe and unavoidable impurities. The strip thickness is 1.00.04 mm

(12) TABLE-US-00004 TABLE 4 The mass percentages of the chemical composition of the strip steel of Example 3 (unit: %) C Si Mn P S Al B N O 0.0023 0.003 0.18 0.016 0.0036 0.001 0.0052 0.0021 0.013

(13) Process: parameters in hot-rolled process: heating temperature 1200 C.; final rolling temperature 900 C.; reeling temperature 720 C.; cold-rolled reduction rate 40%.

(14) The specific processing parameters according to the annealing method of present invention are: 81020 C. at a heating stage; 81020 C. at a soaking stage, the soaking time is 110 s; an outlet temperature of 650 C. at a slow-cooling stage, the cooling speed in slow-cooling stage is 6 C./s; an outlet temperature of 400 C. at a fast-cooling stage, the cooling speed of the fast-cooling stage is 25 C./s; and 300 C. at an overaging stage; the annealing medium is a non-oxidizing atmosphere composed of H.sub.2 and N.sub.2. The leveling elongation rate of the annealed sheet strip is controlled within the range of 0.20.1%.

(15) Implementation results: coercive force He of continuous annealing of cold-rolled electromagnetic pure iron sheet strip: 80 A/m, yield strength: 157 Mpa, elongation: 50.3%. It has a good overall performance.

Example 4

(16) Components: the percent composition by mass of the elements of the strip steel is shown in Table 5, and the rest is Fe and unavoidable impurities. The strip thickness is 1.80.04 mm.

(17) TABLE-US-00005 TABLE 5 The mass percentages of the chemical composition of the strip steel of Example 4 (unit: %) C Si Mn P S Al B N O 0.0030 0.003 0.18 0.019 0.003 0.002 0.0001 0.0016 0.017

(18) Process: parameters in hot-rolled process: heating temperature 1120 C.; final rolling temperature 870 C.; reeling temperature 700 C.; cold-rolled reduction rate 40%.

(19) The specific processing parameters according to the annealing method of present invention are: 81020 C. at a heating stage; 81020 C. at a soaking stage, the soaking time is 130 s; an outlet temperature of 675 C. at a slow-cooling stage, the cooling speed in slow-cooling stage is 5 C./s; an outlet temperature of 400 C. at a fast-cooling stage, the cooling speed of the fast-cooling stage is 25 C./s; and 300 C. at an overaging stage; the annealing medium is a non-oxidizing atmosphere composed of H.sub.2 and N.sub.2. The leveling elongation rate of the annealed sheet strip is controlled within the range of 0.20.1%.

(20) Implementation results: coercive force He of continuous annealing of cold-rolled electromagnetic pure iron sheet strip: 84 A/m, yield strength: 165 Mpa, elongation: 52%. It has a good overall performance.

Comparative Example

(21) Components: the percent composition by mass of the elements of the strip steel is shown in Table 6, and the rest is Fe and unavoidable impurities. The strip thickness is 1.80.04 mm.

(22) TABLE-US-00006 TABLE 6 The mass percentages of the chemical composition of the strip steel of Comparative example C Si Mn P S Al B N O 0.0030 0.003 0.18 0.019 0.003 0.002 0.0001 0.0016 0.017

(23) Process: parameters in hot-rolled process: heating temperature 1120 C.; final rolling temperature 870 C.; reeling temperature 700 C.; cold-rolled reduction rate 40%.

(24) Annealing method: 56020 C. at a heating stage; 56020 C. at a soaking stage, the soaking time is 100 s; an outlet temperature of 500 C. at a slow-cooling stage, the cooling speed in slow-cooling stage is 5 C./s; an outlet temperature of 370 C. at a fast-cooling stage, the cooling speed of the fast-cooling stage is 25 C./s; and 280 C. at an overaging stage; the annealing medium is a non-oxidizing atmosphere composed of H.sub.2 and N.sub.2. The leveling elongation rate of the annealed sheet strip is controlled within the range of 1.00.2%.

(25) Implementation results: coercive force He of continuous annealing of cold-rolled electromagnetic pure iron sheet strip: 127 A/m, yield strength: 213 Mpa, elongation: 42%. The final products have an over-high coercive force, which cannot meet the requirements of the use of magnetic shielding materials.