CN110802342B - High-strength weathering steel Q550NQR1 and Q550qNH matched welding rod - Google Patents

Abstract

The invention discloses a welding electrode matched with high-strength weathering steel Q550NQR1 and Q550qNH, wherein a coating comprises the following components in parts by weight: 35-39 parts of carbonate, 24-30 parts of fluoride, 4-7 parts of rutile, 4-8 parts of silicon dioxide, 3-5 parts of ferromanganese, 3-5 parts of ferrosilicon, 9-12 parts of nickel powder, 2.5-5 parts of metal chromium, 0.5-1.0 part of copper powder and 1-2 parts of binder. In the welding process of the welding rod, the welding process has the advantages of excellent performance, stable electric arc, easy slag removal, small splashing, attractive weld formation, good all-position operability, reasonable control of deposited metal alloy elements, good mechanical properties, impact absorption energy at-40 ℃ of more than or equal to 100J, atmospheric corrosion resistance index I of 12.4 and capability of meeting the corrosion resistance index requirements (I of more than or equal to 6.5) of high-strength weathering steel Q550NQR1, Q550qNH and the like.

Description

High-strength weathering steel Q550NQR1 and Q550qNH matched welding rod

Technical Field

The invention belongs to the technical field of welding materials, and particularly relates to a high-strength weather-resistant welding rod, a welding rod coating and a preparation method of the welding rod.

Background

In the field of rail transit, railway vehicles are constantly subjected to atmospheric corrosion and dynamic load abrasion in the using process, the severe working condition environment requires that the used steel has the performances of high reliability, long service life, light weight and the like, the railway vehicles are developed in the direction of high speed and heavy load, the steel materials for the railway vehicles are also developed in the direction of high strength atmospheric corrosion resistant steel from low strength common carbon steel and low strength atmospheric corrosion resistant steel, and in recent years, Q550NQR1 novel high strength weather resistant steel with higher strength and higher weather resistance is developed and applied. In the field of bridges, bridges develop towards high load, high earthquake resistance, coating-free and high weather resistance, and the novel high-strength atmospheric corrosion resistant bridge steel Q550qNH developed at home and abroad has excellent strength, toughness and welding performance and good atmospheric corrosion resistance so as to ensure the service life and safety of the bridges. Welding is a key process in manufacturing, installing and maintaining, and the quality and performance of joints have an important determining role in the safe service of the weather-resistant steel structures, wherein welding materials are one of key factors influencing the performance of the welded joints. In order to meet the development requirements of rail transit and bridge construction, higher requirements are provided for a high-strength weather-resistant steel welding joint with the yield strength of 550MPa, the high-strength weather-resistant performance of the welding joint is required, and meanwhile, the welding joint is ensured to have excellent impact toughness at the low temperature of-40 ℃. The prior art does not have the research on welding rods which can meet the requirements and have excellent corrosion resistance and low-temperature impact toughness, so the invention provides the invention for developing the welding rod which can be used for high-strength weathering steel with the yield strength of 550MPa, such as Q550NQR1, Q550qNH, and the like, and has excellent toughness at the low temperature of-40 ℃.

Disclosure of Invention

The invention aims to: the defects in the prior art are overcome, the high-strength weathering steel Q550NQR1 and Q550qNH matched welding rods are provided, and the welding joints have excellent low-temperature-resistant toughness.

In order to achieve the purpose, the invention adopts the technical scheme that: a high-strength weathering steel Q550NQR1 and Q550qNH matched welding electrode comprises the following components in parts by weight: 35-39 parts of carbonate, 24-30 parts of fluoride, 4-7 parts of rutile, 4-8 parts of silicon dioxide, 3-5 parts of ferromanganese, 3-5 parts of ferrosilicon, 9-12 parts of nickel powder, 2.5-5 parts of metal chromium, 0.5-1.0 part of copper powder and 1-2 parts of binder.

Further, the paint comprises the following components in parts by weight: carbonate salt: 35.0, fluoride: 29.0, rutile: 7, silicon micropowder: 5.0, low-carbon ferromanganese: 4.0, silicon iron: 4.0, nickel powder: 10.9, metallic chromium: 2.8, copper powder: 0.8, binder: 1.5.

further, carbonate: 36.0, fluoride: 26.0, rutile: 6.0, silicon micropowder: 6.0, low-carbon ferromanganese: 3.5, ferrosilicon: 4.5, nickel powder: 11.9, metallic chromium: 3.6, copper powder: 0.6, binder: 1.9.

further, carbonate: 38.0, fluoride: 25.0, rutile: 5.0, silicon micropowder: 7.5, low-carbon ferromanganese: 4.5, ferrosilicon: 3.5, nickel powder: 10.0, metallic chromium: 4.3, copper powder: 0.9, binder: 1.3.

the welding rod comprises a core wire and the coating, wherein the core wire comprises the following components in percentage by mass:

c: less than or equal to 0.10 percent; mn: 0.30-0.55%; si: less than or equal to 0.08 percent; s is less than or equal to 0.010 percent; p: less than or equal to 0.010 percent; cr: less than or equal to 0.10 percent; ni is less than or equal to 0.30 percent; al: less than or equal to 0.03 percent; cu: less than or equal to 0.20 percent; as: less than or equal to 0.01 percent; the balance being Fe.

Further, the mass ratio of the core wire to the coating is 3: 7. The ratio of the core wire to the coating is set to be 3:7, the coating generates complex chemical reaction in the welding process, on one hand, the coating is in transition alloy to deposited metal, on the other hand, protective gas is generated to protect a liquid molten pool from being oxidized, nitrided and the like by air, and chemical reaction products (mainly silicon and aluminate) form slag to cover the surface of the molten pool, so that the gradually cooled high-temperature molten pool is further protected. The proportion in the proportion range can fully ensure the transition of alloy elements and the welding seam metal not to be oxidized and nitrided by air, thereby ensuring the stable comprehensive performance of the welding seam metal.

A method for preparing welding electrodes matched with high-strength weathering steel Q550NQR1 and Q550qNH comprises the following steps,

(a) uniformly mixing the powder of the coating;

(b) adding water glass which accounts for 21-23wt% of the mass content of the powder components, and carrying out wet mixing, wherein the potassium-sodium ratio of the water glass is 1:1, and the Baume concentration is 41-43 Be;

(c) loading the mixture obtained in the step (b) on the core wire on a hydraulic rod welding machine to prepare the welding rod.

In the present invention, the metal carbonates (CaCO3, BaCO3, etc.) in the coating composition have the function of explaining the evolution of CO2 gas in the electric arc, thereby isolating the liquid metal from the atmosphere and protecting the metal transition, while reducing the partial pressure of hydrogen and nitrogen in the electric arc atmosphere. The metal carbonate also has the function of producing alkaline slag and has better capability of removing sulfur and phosphorus in the slag. The content of carbonate in the sheath is less than 35%, the amount of gas generated is insufficient, and thus good protection cannot be maintained, the amount of hydrogen and nitrogen in the weld metal increases, and toughness and crack resistance decrease. In contrast, when the content of the metal carbonate in the coating exceeds 39%, the arc becomes unstable, resulting in an increase in the amount of spatter. In the present invention, the carbonate content is in the range of 35 to 39 mass%.

In the coating components, fluoride can reduce the melting point of slag to improve the fluidity of welding metal, so that a welding seam is better formed. The fluorine of the fluoride decomposition reacts with hydrogen in the molten metal and slag to reduce the partial pressure of hydrogen in the molten metal, thereby reducing the hydrogen content. When the CaF2 content in the coating is less than 24%, the viscosity of the molten slag is insufficient, and weld formation is poor. In contrast, when the CaF2 content in the coating exceeds 30%, the arc stability becomes poor. More preferably, the content of CaF2 is in the range of 24% to 30%.

TiO2 can be added into the coating as slag-making material. The proper amount of TiO2 can stabilize electric arc, improve molten drop transition mode, and make the weld seam beautiful. When the content of TiO2 exceeds 7%, the weld metal is easy to have a coarse lath bainite structure, and the toughness of the weld metal is greatly reduced. When the content of TiO2 is less than 4%, the effects of stabilizing electric arcs and improving weld seam formation cannot be achieved. Therefore, in the invention, the content of TiO2 in the coating is controlled within the range of 4-7%.

SiO2 is added into the coating as slag-forming material or adhesive. SiO2 can stabilize electric arc, improve physical characteristics of molten slag, regulate molten slag form under the combined action of other slag-forming components, and control the content range as follows: 4 to 8 percent. If the SiO2 content is more than 8%, the slag becomes glassy and the detachability is reduced. In contrast, if the SiO2 content is less than 4%, it is difficult to obtain the effect as a slag-forming material or a bond, and the quality of the coating layer in actual production is degraded, which results in poor productivity. Therefore, the SiO2 content of the coating skin is in the range of 4% -8%.

The element Si (ferrosilicon) is an element used as a deoxidizer, and has an effect of ensuring the strength of the weld metal and reducing the amount of oxygen therein. When the Si content is less than 5%, deoxidation is insufficient, resulting in poor porosity and toughness. On the contrary, if the Si content is more than 5%, the viscosity of the weld metal increases, resulting in a decrease in weldability. Therefore, the Si content is in the range of 3% to 5%.

Mn (low-carbon ferromanganese) is added as a deoxidizer and is combined with Si to realize deoxidation, so that the toughness of the welding metal is improved. When the Mn content is less than 3%, deoxidation is insufficient, thereby generating pores. When the Mn content is more than 5%, the strength of the weld metal increases, enhancing the cold crack sensitivity. Therefore, the Mn content is in the range of 3% to 5%.

Nickel powder: ni can promote the formation of acicular ferrite of the welding seam, improve the impact toughness of the welding seam, and keep a proper proportion of the Ni and Mn to be matched, thereby being beneficial to the full play of the function of the Mn; meanwhile, Ni can change the self-corrosion potential of the welding line to the positive direction, and the corrosion resistance of the welding line is improved. When the content of Ni exceeds 12%, the increase in viscosity of molten drop metal leads to an increase in spatter, deteriorating weld formation; since Ni is an expensive element, the cost easily becomes too high. Ni is less than 9 percent, and the weather resistance is insufficient. Therefore, the content ranges of the invention are controlled as follows: 9 to 12 percent.

Metallic chromium: the alloy is added as an alloying agent, has good strengthening effect on weld metal, can form a compact Cr2O3 oxide film, improves the passivation capability of the weld, improves the weather resistance, and has obvious matching effect with other elements. When the amount exceeds 5% by mass, the strength becomes high, the toughness is also lowered, and cold cracking is likely to occur. Less than 2.5% corrosion resistance is not effective. Therefore, the content range of the invention is controlled to be 2.5-5%.

Copper powder is added as an alloying agent and is an element necessary for improving weather resistance, and Cu plays a role of activating a cathode in the atmospheric corrosion process of a welding seam, promotes the anodic passivation of the welding seam, and reduces the corrosion rate of the welding seam by matching with other elements. More than 1.0 percent of copper powder will damage the toughness of the welding line, and less than 0.5 percent of copper powder will not play a role in improving the weather resistance of the welding line, so the content of the copper powder is controlled to be 0.5 to 1.0 percent.

Adhesive: guarantee the smooth and easy nature of production process, improve and press the coating performance.

The invention has the beneficial effects that: in the welding process of the welding rod, the welding process has the advantages of excellent performance, stable electric arc, easy slag removal, small splashing, attractive weld formation, good all-position operability, reasonable control of deposited metal alloy elements, good mechanical properties, impact absorption energy at-40 ℃ of more than or equal to 100J, atmospheric corrosion resistance index I of 12.4 and capability of meeting the corrosion resistance index requirements (I of more than or equal to 6.5) of high-strength weathering steel Q550NQR1, Q550qNH and the like.

Detailed Description

Example (b):

preparation of the coatings, corresponding coating mixtures were prepared according to the corresponding components and contents in table 1.

TABLE 1 Components and contents of skins of examples 1-6 and comparative examples 1-2

According to the components in the table 1, the components of the coating are uniformly mixed, water glass (Baume density is 41-43Be) with potassium-sodium ratio of 1:1 at 20 ℃ accounting for 21-23wt% of the weight of the coating is added and uniformly stirred, the mixture is sent into an oil press to Be coated on the surface of a core wire, and the surface of the core wire is baked at low temperature of 80 ℃ and high temperature of 350 ℃ to form the welding rod.

In examples 1 to 6, the mass ratio of the sheath to the core wire was 3: 7.

wherein the compositions of the core wires corresponding to the coatings of examples 1-6 are shown in Table 2

TABLE 2 supporting core wire compositions and contents of examples 1-6 and comparative examples 1-2

Composition of	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6	Comparative example 1	Comparative example 2
									C	0.1	0.084	0.038	0.098	0.03	0.1	0.1	0.1
Mn	0.55	0.356	0.325	0.525	0.43	0.55	0.55	0.55
									Si	0.08	0.073	0.05	0.063	0.063	0.08	0.08	0.08
S	0.01	0.086	0.0056	0.0073	0.0043	0.01	0.01	0.01
									P	0.01	0.067	0.0089	0.0076	0.0038	0.01	0.01	0.01
Cr	0.08	0.056	0.071	0.088	0.035	0.08	0.08	0.08
									Ni	0.29	0.263	0.16	0.26	0.26	0.29	0.29	0.29
Al	0.28	0.024	0.026	0.015	0.026	0.28	0.28	0.28
									Cu	0.17	0.13	0.19	0.11	0.13	0.17	0.17	0.17
As	0.0068	0.0046	0.0089	0.0076	0.0068	0.0068	0.0068	0.0068
									Fe	Balance of	Balance of	Balance of	Balance of	Balance of	Balance of	Balance of	Balance of

As shown in table 2 above, the core wires of comparative examples 1 and 2 are the same as the core wire of example 1.

Experimental example:

q550NQR1 high-strength weathering steel is used as a base material, the base material is welded by adopting direct current reversal connection, welding rods of examples 1-6 and comparative examples 1-2 are respectively used for welding, the sampling of metal stretching and impact tests is respectively carried out according to the standard GB2651-2008 welding joint stretching test method and GB2650-2008 welding joint impact test method, the measurement of atmospheric corrosion resistance index is carried out according to the standard GB714-2015 structural steel for bridges, after welding, the yield strength, the tensile strength, the elongation percentage, -40 ℃ impact absorption energy and the atmospheric corrosion resistance index are tested, the results are shown in Table 3,

TABLE 3 mechanical properties of the weld joints of examples 1-6 and comparative examples 1-2

From the above table 3, it can be seen that the yield strength of the welded joints of examples 1 to 6 is within 570MPa to 610MPa, and the tensile strength is within 680MPa to 730MPa, and the welded joints have excellent mechanical properties, and are suitable for the construction requirements of high-strength weathering steels Q550NQR1, Q550qNH and other strength-level coating-free weathering bridges and railway bridges. In examples 1 to 6 of the present invention, the welded joint had an elongation of 22% to 25%, an atmospheric corrosion resistance index of 12 to 15, and excellent corrosion resistance.

The composition and content of the deposited metal after welding were measured, and the results are shown in table 4:

TABLE 4 deposited metal compositions and contents of examples 1-6 and comparative examples 1-2

Composition of	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6	Comparative example 1	Comparative example 2
									C	0.03	0.04	0.037	0.042	0.029	0.033	0.032	0.028
Mn	0.67	0.62	0.72	0.75	0.61	0.78	0.60	0.72
									Si	0.16	0.17	0.145	0.142	0.19	0.20	0.17	0.19
S	0.007	0.008	0.007	0.006	0.008	0.006	0.006	0.008
									P	0.01	0.007	0.009	0.009	0.010	0.009	0.009	0.008
Cr	1	1.26	1.30	1.35	0.98	1.12	0.99	1.05
									Ni	3.5	3.78	3.2	3.15	3.6	3.82	3.48	1.88
Cu	0.28	0.32	0.26	0.26	0.22	0.23	0.003	0.22

Claims (6)

1. A high-strength weathering steel Q550NQR1, Q550qNH mating welding electrode is characterized by comprising a coating and a core wire;

the coating comprises the following components in parts by weight: 35-39 parts of carbonate, 24-30 parts of fluoride, 4-7 parts of rutile, 4-8 parts of silicon dioxide, 3-5 parts of ferromanganese, 3.5-5 parts of ferrosilicon, 9-12 parts of nickel powder, 3-5 parts of metal chromium, 0.5-1.0 part of copper powder and 1-2 parts of binder.

2. The high strength weathering steel Q550NQR1, Q550qNH mating electrode of claim 1, characterized in that: carbonate salt: 36.0, fluoride: 26.0, rutile: 6.0, silica: 6.0, ferromanganese: 3.5, ferrosilicon: 4.5, nickel powder: 11.9, metallic chromium: 3.6, copper powder: 0.6, binder: 1.9.

3. the high strength weathering steel Q550NQR1, Q550qNH mating electrode of claim 1, characterized in that: carbonate salt: 38.0, fluoride: 25.0, rutile: 5.0, silica: 7.5, ferromanganese: 4.5, ferrosilicon: 3.5, nickel powder: 10.0, metallic chromium: 4.3, copper powder: 0.9, binder: 1.3.

4. the high strength weathering steel Q550NQR1, Q550qNH mating electrode of claim 1, characterized in that: the welding core comprises the following components in percentage by mass:

c: less than or equal to 0.10 percent; mn: 0.30-0.55%; si: less than or equal to 0.08 percent; s is less than or equal to 0.010 percent; p: less than or equal to 0.010 percent; cr: less than or equal to 0.10 percent; ni is less than or equal to 0.30 percent; al: less than or equal to 0.03 percent; cu: less than or equal to 0.20 percent; as: less than or equal to 0.01 percent; the balance being Fe.

5. The high-strength weathering steel Q550NQR1, Q550qNH mating welding rod of claim 4, characterized in that: the mass ratio of the core wire to the coating is 3: 7.

6. The preparation method of the welding electrode matched with the high-strength weathering steel Q550NQR1 and Q550qNH as in any of the claims 1 to 5 is characterized in that: comprises the following steps of (a) carrying out,

(a) uniformly mixing the powder of the coating;

(b) adding water glass which accounts for 21-23wt% of the mass content of the powder components, and carrying out wet mixing, wherein the potassium-sodium ratio of the water glass is 1:1, and the Baume concentration is 41-43 Be;

(c) loading the mixture obtained in the step (b) on the core wire on a hydraulic rod welding machine to prepare the welding rod.