TWI555602B - High strength and high toughness low alloy steel electrode - Google Patents

Description

High strength, high toughness, low alloy steel electrode

The invention relates to the field of welding materials, in particular to a manual welding electrode for high strength steel of 80 kg class.

With the further development of the machinery industry and manufacturing industry, in order to improve the performance of steel structure products, a large number of high-strength steels have been used, which has greatly increased the demand for matching welding materials. In general, as the strength of the welding material increases, the impact toughness of the deposited metal will decrease, and how to balance the two has always been the goal pursued by the industry.

In order to overcome the above drawbacks, the present invention provides a high-strength, high-toughness and low-alloy steel welding electrode, which is suitable for both AC and DC, has excellent all-round welding performance, stable arc, no arcing phenomenon, small splash, and easy slag removal.

The high-strength, high-toughness, low-alloy steel electrode of the present invention comprises a core and a coating applied to the outer wall of the core, the coating having a weight coefficient of 0.4 to 0.5 based on the total weight of the electrode. Based on the total weight of the coating, the coating comprises: calcium carbonate: 20 to 30%; magnesium carbonate: 1 to 5%; barium carbonate: 5 to 10%; calcium fluoride: 10 to 20% by weight %; cryolite: 1 to 8%; barium fluoride: 1 to 5%; rutile: 3 to 8%; titanium dioxide: 1 to 5%; cerium oxide: 2 to 10%; electrolytic manganese: 5 to 10 %; strontium iron: 2 to 5%; nickel powder: 4 to 8%; chromium powder: 1 to 3%; and molybdenum powder: 1 to 3%.

Preferably, based on the total weight of the core, and according to the weight percentage, the core comprises: C: 0.01 to 0.08%; Si: 0.10 to 0.25%; Mn: 0.30 to 0.55%; Cr: 0.005 to 0.20% Ni: 0.005 to 0.30%; P: 0.007 to 0.012%; S: 0.005 to 0.012%; and the balance being Fe.

The chemical composition of the deposited metal formed by the electrode of the present invention comprises: C: 0.045-0.075%, Si: 0.1-0.4%, Mn: 1.3-1.8%, Ni: 2.0-2.5%, Cr: 0.01-% by weight. 0.40%; Mo: 0.3 to 0.5%; P: 0.005 to 0.010%; S: 0.005 to 0.01%; the balance being Fe.

Specifically, the performance of each component of the coating of the present invention in the electrode is as follows: the main functions of the carbonate (including magnesium carbonate, calcium carbonate, strontium carbonate) in the electrode are slagging and gasification. When the carbonate content is low, the gas-making and slagging ability of the coating is reduced, the protection effect on the weld is reduced, and the mechanical properties of the weld are degraded; if the content of the carbonate is too high, the gas production of the coating is too large, and the arc is stable. The property is reduced, the splash is increased, the melting point of the slag is increased, and the weld bead is rough. The total amount of carbonate in the present invention is preferably controlled to be from 30 to 45%.

Fluoride (including calcium fluoride, cryolite, barium fluoride) can reduce the surface tension of liquid metal, improve its fluidity, make the weld be beautiful, and reduce the defects of the weld to form pores. The low fluoride content makes the weld be formed poorly, and the weld hole is easy to be vented, and the fluoride content is too high, which easily breaks the arc stability and deteriorates the processability of the electrode. The content of fluoride in the electrode of the present invention is preferably 15 to 30%.

The addition of rutile can stabilize the welding arc, calm the molten pool, refine the transition droplets, make the weld bead beautiful, and cover the slag well. However, excessive use can easily cause serious deterioration of mechanical properties, so the content is controlled at 3 to 8%. .

As a slagging agent, cerium oxide can increase the slag's activity, but excessive use will increase the slag, and its content is controlled at 2 to 10%.

Neodymium iron is a deoxidizer. To ensure the deoxidation effect, the Si content in the deposited metal should be not less than 0.1%. At the same time, Si has a solid solution strengthening effect, which can increase the strength of the deposited metal, but lowers the impact toughness, especially when Si is more than 0.4%, the impact toughness is lowered.

Electrolytic manganese is mainly used to improve the strength of deposited metal, and also plays the role of deoxidation and desulfurization. The Mn content in the deposited metal should be not less than 1.30%. As the Mn content increases, the strength of the deposited metal increases, and the impact toughness The law of rising first and then decreasing, when Mn is greater than 1.80%, the impact toughness decreases.

Nickel powder is the main element to improve the toughness of deposited metal. With the increase of Ni content in the deposited metal, the toughness of the deposited metal gradually increases. When Ni>2.0%, the impact toughness is obviously improved, but when the Ni content exceeds 2.5%. Ni does no longer have the effect of improving impact toughness, but the impact toughness is rather reduced.

The chromium powder can effectively increase the strength of the deposited metal, but at the same time reduce the impact toughness, so the Cr content in the deposited metal should be controlled to 0.01 to 0.40%.

Molybdenum powder is also an element to improve the strength of deposited metal. It is characterized by a decrease in impact toughness with increasing Mo content when the Mo content is low. When the Mo content is increased to a certain extent, the impact toughness is significantly reduced. A suitable range of Mo content should be between 0.30 and 0.50%.

The welding rod is used for welding, the weld strength is greater than 800 MPa, the impact toughness at -50 °C is greater than 60 J, and the diffusible hydrogen content is between 2 and 3 ml/100 g, which is mainly suitable for welding of low-alloy steel structures of 80 kg class.

The invention has the beneficial effects that the steel electric welding material of the invention is suitable for both AC and DC, and has the advantages of excellent all-round welding performance, stable arc, no arcing phenomenon, small splashing, easy slag removal and the like.

The low-alloy steel electric welding material of the invention comprises a welding core and a coating coated on the outer wall of the welding core, the welding core adopts a special carbon steel core wire, and the composition thereof is as follows (weight percentage):

The drug skin accounts for 40%-50% of the total weight of the core and the coating. The composition of the skin is as follows (weight percentage):

For a better understanding of the invention, it is further illustrated by the following examples 1-6, but the invention is not limited to the following examples:

Example 1:

Using the common manufacturing process in the welding rod production industry, the core is prepared according to the core formula of Table 1-1, prepared according to the coating formula of Table 1-2, and the electrode coating is prepared by dry mixing and wet mixing, and the electrode coating is applied. The coating is applied to the outer wall of the core to form:

Table 1-1 Core formula (unit: weight percentage)

Table 1-2 Formula of the skin (unit: weight percentage)

The chemical composition of the deposited metal is shown in Table 1-3, the mechanical properties are shown in Table 1-4, and the diffusion hydrogen content is shown in Table 1-5. The diffusion hydrogen is determined by gas chromatography, and the two samples are averaged.

Table 1-3 Chemical composition of deposited metal (unit: percentage of electrode weight)

Table 1-4 Mechanical properties of deposited metal

Table 1-5 Diffusion hydrogen content of deposited metal

Example 2:

Using the common manufacturing process in the welding rod production industry, the core is prepared according to the core formula of Table 2-1, prepared according to the coating formula of Table 2-2, and the electrode coating is prepared by dry mixing and wet mixing, and the electrode coating is applied. The coating is applied to the outer wall of the core to form:

Table 2-1 Core formula (unit: weight percentage)

Table 2-2 Formula of the skin (unit: weight percentage)

The chemical composition of the deposited metal is shown in Table 2-3, the mechanical properties are shown in Table 2-4, and the diffusion hydrogen content is shown in Table 2-5. The diffusion hydrogen is determined by gas chromatography, and the two samples are averaged:

Table 2-3 Chemical composition of deposited metal (% by weight)

Table 2-4 Mechanical properties of deposited metal

Table 2-5 Diffusion hydrogen content of deposited metal

Example 3:

Using the common manufacturing process in the welding rod production industry, the core is prepared according to the core formula of Table 3-1, prepared according to the coating formula of Table 3-2, and the electrode coating is prepared by dry mixing and wet mixing, and the electrode coating is applied. The coating is applied to the outer wall of the core to form:

Table 3-1 Core formula (unit: weight percentage)

Table 3-2 Formula of the skin (unit: weight percentage)

The chemical composition of the deposited metal is shown in Table 3-3, the mechanical properties are shown in Table 3-4, and the diffusion hydrogen content is shown in Table 3-5. The diffusion hydrogen is determined by gas chromatography, and the two samples are averaged:

Table 3-3 Chemical composition of molten metal (% by weight)

Table 3-4 Mechanical properties of deposited metal

Table 3-5 Diffusion hydrogen content of deposited metal

Example 4:

Using the common manufacturing process in the welding rod production industry, the welding core is prepared according to the welding core formula of Table 4-1, prepared according to the coating formula of Table 4-2, and the welding rod coating is prepared by dry mixing wet mixing, and the welding rod coating is The coating is applied to the outer wall of the core to form:

Table 4-1 Core formula (unit: weight percentage)

Table 4-2 Formula of the skin (unit: weight percentage)

The chemical composition of the deposited metal is shown in Table 4-3, the mechanical properties are shown in Table 4-4, and the diffusion hydrogen content is shown in Table 4-5. The diffusion hydrogen is determined by gas chromatography and the two samples are averaged:

Table 4-3 Chemical composition of molten metal (% by weight)

Table 4-4 Mechanical properties of deposited metal

Table 4-5 Diffusion hydrogen content of deposited metal

Example 5:

Using the common manufacturing process in the welding rod production industry, the core is prepared according to the core formula of Table 5-1, prepared according to the coating formula of Table 5-2, and the electrode coating is prepared by dry mixing and wet mixing, and the electrode coating is applied. The coating is applied to the outer wall of the core to form:

Table 5-1 Core formula (unit: weight percentage)

Table 5-2 Formula of the skin (unit: weight percentage)

The chemical composition of the deposited metal is shown in Table 5-3, the mechanical properties are shown in Table 5-4, and the diffusion hydrogen content is shown in Table 5-5. The diffusion hydrogen is determined by gas chromatography and the two samples are averaged:

Table 5-3 Chemical composition of the deposited metal (% by weight)

Table 5-4 Mechanical properties of deposited metal

Table 5-5 Diffusion hydrogen content of deposited metal

Example 6

Using the common manufacturing process in the welding rod production industry, the core is prepared according to the core formula of Table 6-1, prepared according to the coating formula of Table 6-2, and the electrode coating is prepared by dry mixing and wet mixing, and the electrode coating is applied. The coating is applied to the outer wall of the core to form:

Table 6-1 Solder core formula (unit: weight percentage)

Table 6-2 Formula of the skin (unit: weight percentage)

The chemical composition of the deposited metal is shown in Table 6-3, the mechanical properties are shown in Table 6-4, and the diffusion hydrogen content is shown in Table 6-5. The diffusion hydrogen is determined by gas chromatography and the two samples are averaged:

Table 6-3 Chemical composition of molten metal (% by weight)

Table 6-4 Mechanical properties of deposited metal

Table 6-5 Diffusion hydrogen content of deposited metal

In summary, the welding rod is used for welding, the weld strength is greater than 800 MPa, the impact toughness at -50 °C is greater than 60 J, and the diffusible hydrogen content is between 2 and 3 ml/100 g, which is mainly suitable for welding of low-alloy steel structures of 80 kg class. .

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

Claims (3)

A high-strength, high-toughness, low-alloy steel electrode comprises: a core, and a coating applied to the outer wall of the core, the coating having a weight coefficient of 0.4 to 0.5, based on the total weight of the electrode, Based on the total weight, the coating comprises: calcium carbonate: 20~30%; magnesium carbonate: 1~5%; barium carbonate: 5~10%; calcium fluoride: 10~20%; cryolite :1~8%; barium fluoride: 1~5%; rutile: 3~8%; titanium dioxide: 1~5%; cerium oxide: 2~10%; electrolytic manganese: 5~10%; : 2~5%; nickel powder: 4~8%; chromium powder: 1~3%; and molybdenum powder: 1~3%; based on the total weight of the core, and according to the weight percentage, the core comprises: C: 0.01~0.08%; Si: 0.10~0.25%; Mn: 0.30~0.55%; Cr: 0.005 to 0.20%; Ni: 0.005 to 0.30%; P: 0.007 to 0.012%; S: 0.005 to 0.012%; and Fe: balance. The high-strength, high-toughness, low-alloy steel electrode according to the first aspect of the patent application, wherein the total amount of calcium carbonate, magnesium carbonate and barium carbonate in the coating is 30 to 45%. The high-strength, high-toughness, low-alloy steel electrode according to the first aspect of the patent application, wherein the total amount of calcium fluoride, cryolite and barium fluoride in the coating is 15 to 30%.