Welding wire and welding method for reducing strip breakage rate of normalized welding seam of high-silicon non-oriented silicon steel

Abstract

The invention discloses a welding wire and a welding method for reducing the strip breakage rate of a normalized weld joint of high-silicon non-oriented silicon steel. The welding wire comprises the following chemical components in percentage by mass: 0.15%-0.20% of C, less than or equal to 0.35% of Si, 2.0%-2.5% of Mn, 2.0%-2.5% of Ni, 0.8%-1.0% of Cr and the balance of Fe. The welding method comprises the step of carrying out laser welding on the non-oriented silicon steel by using the welding wire as a filling material. By optimizing welding wire components and a welding process, the structure state of a welding seam is regulated and controlled, a bainite structure is formed, plasticity and toughness are enhanced, the percent of pass of a cup drawing test is 100%, and the strip breakage rate of a normalized welding seam is smaller than or equal to 0.05%.

Description

Technical Field

[0001] The invention relates to the technical field of full-process non-oriented silicon steel production and preparation, and in particular to a welding wire and a welding method for reducing the broken strip rate of normalized welds of high-silicon non-oriented silicon steel. Background Art

[0002] In recent years, non-oriented silicon steel has developed towards high grades. Normalization process is an important process in the production of non-oriented silicon steel. In order to achieve continuous production, the front and rear strips need to be welded. Therefore, the quality of the weld directly determines whether the production can proceed smoothly.

[0003] Too high Si content will cause the following situations during welding and affect the welding quality: 1) It is easy to react with oxygen to form pores. The higher the content, the greater the probability of forming pores, thus affecting the quality of the weld; 2) Too high Si content will cause coarse dendritic grains to form in the weld, resulting in a decrease in mechanical properties and reduced plastic toughness; 3) Too high Si will increase the sensitivity to cold and heat during welding, and it is easy to form cracks after welding, etc.

[0004] During normal production of high-grade non-oriented silicon steel, due to the excessively high Si content, the structure at the weld is very different from that of the base material, and the coarse dendritic grains have poor mechanical properties. In actual production, this often leads to broken strips at the weld, affecting the production rhythm and having a great impact on output.

[0005] The Chinese patent document with application number CN201110142365.4 discloses "A method for welding non-oriented silicon steel with filler wire". This document uses low-silicon materials as guide wires and optimizes the welding process to reduce the breakage of the wire during rolling. However, this method is only applicable to non-oriented silicon steel with a silicon content of 1.0% to 3.5%, not to high-grade non-oriented silicon steel, and the breakage of the wire in the normalizing unit is different. This document also does not involve the control of weld structure.

[0006] The Chinese patent document with application number CN201710501693.X published "A method for welding low-grade non-oriented silicon steel with a laser welder". The scope of application of this document is low-grade non-oriented silicon steel. Low-grade silicon steel has low silicon content and will undergo austenitization at high temperature. The weld structure after cooling has small grains and the strength will not differ much from the parent material. However, when only using this method, the weld structure of high-grade non-oriented silicon steel has no phase change, and after welding, it is coarse ferrite, and the weld strength is low. Summary of the invention

[0007] In order to overcome the shortcomings of the above-mentioned technology, the present invention provides a welding wire and a welding method for reducing the broken band rate of the normalized weld of high-silicon non-oriented silicon steel, improving the strength and plastic toughness of the weld, ensuring the quality of the weld, and thus ensuring the production efficiency of high-silicon non-oriented silicon steel.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] A welding wire for reducing the broken strip rate of normalized welds of high-silicon non-oriented silicon steel comprises the following chemical components by mass percentage: C: 0.15%-0.20%, Si: ≤0.35%, Mn: 2.0-2.5%, Ni: 2.0-2.5%, Cr: 0.8-1.0%, and the rest is Fe.

[0010] A welding method for reducing the broken strip rate of normalized welds of high-silicon non-oriented silicon steel comprises: using the welding wire as a filling material to perform laser welding on the non-oriented silicon steel.

[0011] Preferably, the mass percentage of Si in the non-oriented silicon steel is ≥3.3%.

[0012] Preferably, the welding butt gap of the laser welding is 0.45 mm to 0.05 mm.

[0013] Preferably, the welding speed of the laser welding is 2.2-2.7 m / min, and the wire feeding rate is 3-3.5 m / min.

[0014] Preferably, when performing the laser welding, the laser power is 3.0-3.5 KW, the preheating power is 8-14 KW, and the post-heating power is 12-18 KW.

[0015] Preferably, the non-oriented silicon steel produced by the welding method has a normalized weld breakage rate of <0.1%.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] For non-oriented silicon steel with silicon content above 3.3%, due to the high Si content in the weld during normalizing welding, coarse dendritic ferrite is formed at the weld, which has poor strength, plasticity and toughness, and is very different from the organizational state of the parent material. The break rate at the weld is extremely high during production, affecting the production rhythm. Therefore, how to improve the quality of high-Si non-oriented silicon steel welds is currently an urgent problem to be solved.

[0018] The present invention optimizes the welding wire composition and the welding process, adjusts the weld tissue state, forms a bainite structure, strengthens plasticity and toughness, achieves a cupping test pass rate of 100%, and a normalized weld break rate of ≤0.05%.

[0019] (1) Optimization of the composition of the weld zone: Taking into account the characteristics of high-Si non-oriented silicon steel, consider using low-Si welding wire materials containing Cr, Mn, Ni and other elements to optimize and control the composition and structure of the weld. Cr and Mn are austenite stabilizing elements that can reduce the Bs point and promote the formation of bainite structure during the solidification process of the weld. Ni can refine the grains and improve the strength of the weld.

[0020] (2) Optimize the welding process, reduce the width of the heat-affected zone, and regulate the weld quality to ensure weld penetration and forming stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the weld microstructure morphology of Example 2;

[0022] Figure 2 This is the weld microstructure morphology of comparative example 2. DETAILED DESCRIPTION

[0023] In order to better explain the present invention, the main contents of the present invention are further explained below in combination with specific embodiments and drawings, but the contents of the present invention are not limited to the following embodiments.

[0024] Example 1

[0025] A welding wire can reduce the weld breakage rate of high-silicon non-oriented silicon steel during normalizing treatment, comprising the following chemical components in percentage by mass: C: 0.18%, Si: 0.25%, Mn: 2.3%, Ni: 2.4%, Cr: 0.88%, and the remainder is Fe.

[0026] A welding method for reducing the normalized weld breakage rate of high-silicon non-oriented silicon steel, using the above-mentioned welding wire to perform laser welding on high-silicon non-oriented silicon steel. The mass percentage of Si in the non-oriented silicon steel is 3.40%.

[0027] Welding process:

[0028] 1. To ensure the quality of the weld and avoid burn-through and incomplete welding, the welding gap is 0.05mm;

[0029] 2. The welding speed is controlled at 2.6m / min. Taking into account the material properties of the welding wire and the base material, the wire feeding speed is slightly higher than the welding speed and is controlled at 3.1m / min.

[0030] 3. The welding laser power is controlled at 3.2KW, the preheating power is controlled at 12KW, and the post-heating power is controlled at 15KW.

[0031] When the normalized welding scheme is adopted to produce high silicon non-oriented silicon steel, the pass rate of the weld cupping test is 100%, and the normalized weld breakage rate is 0.008%.

[0032] Example 2

[0033] A welding wire can reduce the weld breakage rate during normalization treatment of high-silicon non-oriented silicon steel, comprising the following chemical components in percentage by mass: C: 0.20%, Si: 0.29%, Mn: 2.4%, Ni: 2.2%, Cr: 0.95%, and the remainder is Fe.

[0034] A welding method for reducing the normalized weld breakage rate of high-silicon non-oriented silicon steel, using the above-mentioned welding wire to perform laser welding on high-silicon non-oriented silicon steel. The mass percentage of Si in the non-oriented silicon steel is 3.40%.

[0035] Welding process:

[0036] 1. To ensure the quality of the weld and avoid burn-through and incomplete welding, the welding gap is 0.05mm;

[0037] 2. The welding speed is controlled at 2.6m / min. Taking into account the material properties of the welding wire and the base material, the wire feeding speed is slightly higher than the welding speed and is controlled at 3.1m / min.

[0038] 3. The welding laser power is controlled at 3.2KW, the preheating power is controlled at 12KW, and the post-heating power is controlled at 15KW.

[0039] When the normalized welding scheme is adopted to produce high silicon non-oriented silicon steel, the qualified rate of the weld cupping test is 100% and the normalized weld breakage rate is 0.01%.

[0040] Comparative Example 1

[0041] Laser welding is used for high silicon non-oriented silicon steel without filler material. The mass percentage of Si in non-oriented silicon steel is 3.4%.

[0042] Welding process:

[0043] 1. To ensure the quality of the weld and avoid burn-through and incomplete welding, the welding gap is 0.05mm;

[0044] 2. The welding speed is controlled at 2.3m / min;

[0045] 3. The laser power of the above welding is controlled at 3.2KW, the preheating power is controlled at 12KW, and the post-heating power is controlled at 15KW

[0046] When the above normalized welding scheme is adopted to produce high silicon non-oriented silicon steel, the qualified rate of weld cupping test is 0, and the normalized weld breakage rate is 0.3%.

[0047] Comparative Example 2

[0048] Laser welding is used for high silicon non-oriented silicon steel. The mass percentage of Si in non-oriented silicon steel is 3.40%.

[0049] Welding process:

[0050] 1. Chemical composition of the welding wire used: C: 0.20%, Si: 0.8%, Mn: 1.45%, Ni: 0.05%, Cr: 0.01%, and the rest is Fe.

[0051] 2. To ensure the quality of the weld and avoid burn-through and incomplete welding, the welding gap is 0.05mm;

[0052] 3. Laser welding the welding wire with the above chemical composition to high silicon non-oriented silicon steel;

[0053] 4. The welding speed is controlled at 2.3m / min, and the wire feeding speed is slightly higher than the welding speed and is controlled at 3.1m / min.

[0054] 5. The laser power of welding is controlled at 3.2KW, the preheating power is controlled at 12KW, and the post-heating power is controlled at 15KW

[0055] When the above normalized welding scheme is adopted to produce high silicon non-oriented silicon steel, the pass rate of the weld cupping test is 28%, and the normalized weld breakage rate is 0.3%.

[0056] Comparative Example 3

[0057] Laser welding is used for high silicon non-oriented silicon steel. The mass percentage of Si in non-oriented silicon steel is 3.40%.

[0058] Welding process:

[0059] 1. Chemical composition of the welding wire used: C: 0.20%, Si: 0.8%, Mn: 1.45%, Ni: 0.05%, Cr: 0.01%, and the rest is Fe.

[0060] 2. To ensure the quality of the weld and avoid burn-through and incomplete welding, the welding gap is 0.1mm;

[0061] 3. Laser welding the welding wire with the above chemical composition to high silicon non-oriented silicon steel;

[0062] 4. The welding speed is controlled at 2.3m / min, and the wire feeding speed is slightly higher than the welding speed and is controlled at 3.1m / min.

[0063] 5. The laser power of welding is controlled at 3.2KW, the preheating power is controlled at 12KW, and the post-heating power is controlled at 22KW

[0064] When the above normalized welding scheme is used to produce high-silicon non-oriented silicon steel, the weld cupping test pass rate is 16%, and the normalized weld breakage rate is 0.35%.

[0065] Comparative Example 4

[0066] Laser welding is used for high silicon non-oriented silicon steel. The mass percentage of Si in non-oriented silicon steel is 3.40%.

[0067] Welding process:

[0068] 1. Chemical composition of the welding wire used: C: 0.20%, Si: 0.29%, Mn: 2.4%, Ni: 2.2%, Cr: 0.95%, and the rest is Fe.

[0069] 2. To ensure the quality of the weld and avoid burn-through and incomplete welding, the welding gap is 0.05mm;

[0070] 3. Laser welding the welding wire with the above chemical composition to high silicon non-oriented silicon steel;

[0071] 4. The welding speed is controlled at 2.6m / min, taking into account the material properties of the welding wire and the base material, and the wire feeding speed is controlled at 4.0m / min.

[0072] 5. The laser power of the above welding is controlled at 3.2KW, the preheating power is controlled at 8KW, and the post-heating power is controlled at 22KW.

[0073] When the normalized welding scheme is adopted to produce high silicon non-oriented silicon steel, the pass rate of the weld cupping test is 95%, and the normalized weld breakage rate is 0.05%.

[0074] The welding wire compositions, welding processes, and product properties of Examples 1 and 2 and Comparative Examples 1 to 4 are shown in Tables 1 to 3.

[0075] As shown in Table 3 and Figures 1-2 As shown, the weld obtained by the welding method in Example 2 has a bainite structure, high strength and good plasticity and toughness. The weld obtained by the welding method in Comparative Example 2 has a coarse dendritic ferrite structure, low strength and poor plasticity and toughness.

[0076] It can be seen from Examples 1 to 2 and Comparative Examples 1 to 4 that the present invention optimizes the composition of the welding wire and the welding process, adjusts the weld microstructure, forms a bainite structure, strengthens plasticity and toughness, achieves a cupping test pass rate of 100%, and a normalized weld break rate of ≤0.05%.

[0077] Table 1: Welding wire composition

[0078]

[0079] Table 2: Welding process

[0080]

[0081] Table 3: Weld inspection results

[0082]

Claims

1. A welding wire for reducing the breakage rate of normalized welds of high-silicon non-oriented silicon steel, characterized in that: It includes the following chemical components in percentage by mass: C: 0.15% to 0.20%, Si: ≤0.35%, Mn: 2.0 to 2.5%, Ni: 2.0 to 2.5%, Cr: 0.8 to 1.0%, and the rest is Fe.

2. A welding method for reducing the breakage rate of normalized welds of high-silicon non-oriented silicon steel, characterized in that: The following steps are involved: Laser welding of non-oriented silicon steel is performed using the welding wire described in claim 1 as a filling material.

3. The welding method according to claim 2, characterized in that: The mass percentage of Si in the non-oriented silicon steel is ≥3.3%.

4. The welding method according to claim 2, characterized in that: The welding butt gap of the laser welding is 0.45 mm to 0.05 mm.

5. The welding method according to claim 2, characterized in that: The welding speed of the laser welding is 2.2-2.7 m / min, and the wire feeding rate is 3-3.5 m / min.

6. The welding method according to claim 2, characterized in that: When performing the laser welding, the laser power is 3.0-3.5KW, the preheating power is 8-14KW, and the post-heating power is 12-18KW.

7. The welding method according to any one of claims 2 to 6, characterized in that: The non-oriented silicon steel produced by the welding method has a normalized weld breakage rate of less than 0.1%.

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