CN113798729A

CN113798729A - Rare earth solid welding wire with excellent low-temperature impact toughness

Info

Publication number: CN113798729A
Application number: CN202111114275.4A
Authority: CN
Inventors: 吕刚; 赵晓敏; 杨鲁明; 白月琴
Original assignee: Baotou Iron and Steel Group Co Ltd
Current assignee: Baotou Iron and Steel Group Co Ltd
Priority date: 2021-09-23
Filing date: 2021-09-23
Publication date: 2021-12-17

Abstract

The invention discloses a rare earth solid welding wire with excellent low-temperature impact toughness, which comprises the following chemical components in percentage by mass: 0.06-0.10% of C, 1.40-1.55% of Mn1, 0.80-0.95% of Si, 0.10-0.20% of Cr0.05-0.12% of Ti0.05-0.12% of rare earth element Ce5-30ppm, the balance of Fe and inevitable impurities, wherein P in the impurities is less than or equal to 0.025%, and S in the impurities is less than or equal to 0.025%. The invention is suitable for 600 Mpa-grade solid welding wires, the rare earth Ce element is added into the welding line, the welding line structure is improved by refining welding line grains, the micro-alloying treatment effect of the welding line metal is purified, and the welding line is ensured to have more excellent low-temperature impact toughness on the basis of high strength.

Description

Rare earth solid welding wire with excellent low-temperature impact toughness

Technical Field

The invention relates to the technical field of metallurgy, in particular to a rare earth solid welding wire with excellent low-temperature impact toughness.

Background

The 600MPa welding wire is a common high-strength welding wire, but when welding is carried out, the low-temperature impact toughness of a welding line is low, and the welding wire is always a bottleneck limiting the wide use of the welding wire.

Disclosure of Invention

In order to solve the above technical problems, an object of the present invention is to provide a rare earth solid wire having excellent low-temperature impact toughness.

In order to solve the technical problems, the invention adopts the following technical scheme:

a rare earth solid welding wire with excellent low-temperature impact toughness comprises the following chemical components in percentage by mass: 0.06-0.10% of C, 1.40-1.55% of Mn1, 0.80-0.95% of Si, 0.10-0.20% of Cr0.05-0.12% of Ti0.05-0.12% of rare earth element Ce5-30ppm, the balance of Fe and inevitable impurities, wherein P in the impurities is less than or equal to 0.025%, and S in the impurities is less than or equal to 0.025%.

Further, the chemical components in percentage by mass are as follows: 0.074% of C, 1.52% of Mn1, 0.88% of Si, 0.14% of Cr0.069% of Ti, 9ppm of rare earth element Ce, and the balance of Fe and inevitable impurities, 0.015% of P in the impurities and 0.0022% of S in the impurities.

Further, smelting by a converter, LF refining, small square billet continuous casting, rolling the wire rod into a wire rod with the diameter of 5.5mm, and drawing the wire rod, plating copper and preparing the finished welding wire with the diameter of 1.2 mm.

The chemical components of the invention are designed from a C-Si-Mn-Cr-Ti alloy system by mainly adopting rare earth microalloying.

The action of each element in the welding wire steel is as follows:

carbon: c is a main strengthening element in the weld joint, the hardness, yield strength and tensile strength of weld joint metal are all improved along with the increase of the content of C, but the impact toughness of the weld joint is all reduced along with the increase of the content of C, because C is a gap solid solution strengthening element, matrix lattice is strong and obvious distortion is caused, matrix microcrack is easy to generate and expand, and therefore the impact work of the weld joint metal is greatly reduced. Evans believes that C substantially affects the primary crystal structure at the time of solidification of a weld, and as the C content increases, the prior austenite grain size increases, the width of columnar grains increases, the proportion of acicular ferrite increases, and the number of proeutectoid ferrite decreases. In order to ensure good low temperature toughness of the weld metal, the carbon content in the weld metal must be tightly controlled.

Silicon: si is an element that narrows the γ phase region, and can play a role of solid solution strengthening as an alloy element. The Si in the wire acts as a deoxidizer by reacting with O to form SiO 2. Si can increase the strength of the weld metal, but the toughness of the weld metal is reduced, and the Si content is generally considered to be harmful to the toughness when being more than 0.40%; when the silicon content in the welding seam is 0.25-0.35%, the toughness of the welding seam is favorable. Since the flux contains a certain amount of Si, the Si content in the wire should be reduced accordingly.

Manganese: mn is a stabilizing element for austenitization, and can lower the temperature at which austenite transforms into ferrite. Mn in weld metal serves as a solid solution strengthening component, and in the range that Mn is less than or equal to 2.0 percent, the quantity of acicular ferrite is increased along with the increase of Mn content, and the quantity of pro-eutectoid ferrite and side plate bar ferrite is reduced. And the grain size of acicular ferrite is made finer, and the Mn can improve the toughness of the weld metal and also can improve the strength of the weld metal. Mn in the welding wire can also play a role in deoxidation and can react with sulfur to generate stable MnS, so that the generation of a low-melting-point phase FeS is reduced, and the hot crack resistance and the lamellar tearing resistance of weld metal are improved. The content of Mn in the weld has great influence on the mechanical properties of weld metal, the yield strength and the tensile strength of the weld metal are linearly increased along with the increase of the Mn content, the yield strength and the tensile strength of the weld can be increased by 10MPa for every 0.01 percent increase of Mn, and although the room-temperature impact toughness of the weld metal is not increased by Mn, the non-ductile transition temperature (brittle transition temperature) is obviously reduced.

Chromium: cr can improve the strength and hardness of steel, but the plasticity and toughness are not greatly reduced, and the steel has strong corrosion resistance and acid resistance, and also has strong oxidation resistance and heat resistance.

Titanium: ti is an element for reducing a gamma phase region, is a strong deoxidizer and a Ti (C, N) forming element, and is added into weld metal, the Ti with extremely high affinity with N is added, so that the content of free N in the weld metal can be reduced, and the generated Ti (C, N) and TiO2 inclusion particles can be used as crystal cores, thereby promoting the nucleation of needle-shaped ferrite in austenite crystals and refining weld grains. The addition of a trace amount of Ti in the welding seam can cause dramatic changes to the microstructure and mechanical properties of the welding seam, and when the content of Ti in the welding seam metal reaches 0.01 percent, the microstructure is changed from 80 percent of side plate bar ferrite to 60 percent of acicular ferrite. When the Ti content is less than 0.03%, the amount of acicular ferrite increases as the Ti content increases, but when the Ti content is more than 0.03%, the amount of acicular ferrite decreases as the Ti content increases.

Rare earth element cerium: the rare earth Ce has strong affinity with oxygen and sulfur in steel, can deoxidize and desulfurize, reduce the oxygen content and sulfur content in steel, and can reduce the harm of low-melting-point elements such as phosphorus, hydrogen, arsenic, antimony, lead, tin and the like on crystal boundary. The rare earth can control the form of sulfide inclusion, the sulfide in steel is strip-shaped distributed along the rolling direction of steel material, and the addition of rare earth can make the strip-shaped sulfide become spherical or hammer-like, and can change the size of inclusion, and can obviously improve impact toughness and fatigue property.

Compared with the prior art, the invention has the beneficial technical effects that:

the invention is suitable for 600 Mpa-grade solid welding wires, the rare earth Ce element is added into the welding line, the welding line structure is improved by refining welding line grains, the micro-alloying treatment effect of the welding line metal is purified, and the welding line is ensured to have more excellent low-temperature impact toughness on the basis of high strength.

Detailed Description

Smelting in a converter, LF refining, small square billet continuous casting, rolling a wire rod into a wire rod with the diameter of 5.5mm, and drawing the wire rod, plating copper and preparing the finished welding wire with the diameter of 1.2 mm.

The welding wire comprises the following chemical components:

TABLE 1 Final ingredients (wt%, balance iron)

Content providing method and apparatus	C	Si	Mn	P	S	Cr	Ti	Ce
									Example 1	0.066	0.89	1.50	0.017	0.0024	0.14	0.067	/
Example 2	0.074	0.88	1.52	0.015	0.0022	0.14	0.069	9ppm

Example 1 with no rare earth addition, example 2 with rare earth addition, the finished wire was subjected to a welding test and had the following low temperature impact toughness:

TABLE 2 weld impact test results

The low-temperature impact performance of the welding seam of the rare earth solid welding wire is obviously higher than that of the solid welding wire without rare earth.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims

1. The rare earth solid welding wire with excellent low-temperature impact toughness is characterized by comprising the following chemical components in percentage by mass: 0.06-0.10% of C, 1.40-1.55% of Mn, 0.80-0.95% of Si, 0.10-0.20% of Cr, 0.05-0.12% of Ti0.05-30% of rare earth element Ce, the balance of Fe and inevitable impurities, wherein P in the impurities is less than or equal to 0.025%, and S in the impurities is less than or equal to 0.025%.

2. The rare earth solid welding wire with excellent low-temperature impact toughness of claim 1, wherein the welding wire comprises the following chemical components in percentage by mass: 0.074% of C, 1.52% of Mn, 0.88% of Si, 0.14% of Cr, 0.069% of Ti, 9ppm of rare earth element Ce, and the balance of Fe and inevitable impurities, 0.015% of P in the impurities and 0.0022% of S in the impurities.

3. The rare earth solid wire with excellent low-temperature impact toughness of claim 1 or 2, wherein converter smelting, LF refining, billet continuous casting, wire rolling into a wire rod with the diameter of 5.5mm, and wire drawing, copper plating and wire forming are carried out on the wire rod to obtain a finished welding wire with the diameter of 1.2 mm.