KR20230003246A - Welding wire and welding process for submerged arc welding of Ni-saving low-temperature steel for cryogenic environments - Google Patents

Abstract

The welding wire and welding process of submerged arc welding of Ni-saving low-temperature steel for cryogenic environments are related to the technology of steel smelting, and its chemical composition and mass percentage are as follows, C: 0.01% ~ 0.10% , Mn: 2.0% to 4.5%, Si: 0.10% to 0.20%, S≤0.01%, P≤0.02%, Ni: 9.0% to 15.0%, Cr: 10.0% to 16.0%, Mo≤0.01%, V≤ 0.01%, remaining Fe and unavoidable impurities. Through a reasonable welding process and matched welding materials, the welded seam tensile strength Rm≥530MPa, welded seam and -101℃ impact energy KV ₂ ≥34J in the heat-affected zone are guaranteed, and only the welded seam side d = 4a, 180 ° is acceptable, and the welded joint has excellent overall mechanics performance.

Description

Welding wire and welding process for submerged arc welding of Ni-saving low-temperature steel for cryogenic environments

The present invention relates to the technical field of steel smelting, and in particular, to a welding wire and welding process for submerged arc welding of Ni-saving low-temperature steel for cryogenic environments.

As the international situation changes and energy has a profound impact on the economy, development and crisis coexist in China's domestic petroleum, chemical and other energy industries. Demand for transport storage facilities such as liquefied petroleum gas and liquid methanol is very high, which will provide a very broad market and development opportunities to the manufacturing industry, such as energy production and storage facilities under low temperature service conditions. At the same time, Demand for low-temperature steel will increase day by day.

Currently, Ni-based low-temperature steel is widely applied in the production and manufacturing of low-temperature containers. Metallic Ni has the characteristics of improving the low-temperature toughness of steel, but its high price and the current situation in China where nickel resources are scarce have a certain influence on the continuous application of Ni-based low-temperature steel. With the global demand for energy and resources increasing day by day, reducing the weight of steel and realizing low cost has become an important development direction of the steel industry.

As the technology and process of the steel industry mature day by day, the technical idea of “replacing Ni with Mn” and industrialized production have been developed and practiced in low-temperature steel. In the component design of low-temperature steel, inexpensive metal Mn replaces expensive metal Ni to lower production costs and at the same time guarantee low-temperature toughness, thereby rationally using resources and saving the use of precious metals, as well as effectively lowering the cost of steel materials. It has become a hot issue and trend in the research and development of new low-temperature steel in recent years.

For example, low-cost Ni-saving low-temperature steel has a Ni content of only 0.85% to 1.25%, and is mainly composed of bainite + retained austenite through a Q(DQ)-L-T heat treatment process. Obtain microstructure to ensure that the yield strength reaches 355MPa and the tensile strength reaches 490MPa, while realizing excellent impact toughness not lower than 80J at -101℃, fully meeting the requirements of 3.5Ni low-temperature steel in mechanical performance. did The low-temperature steel can be used for drying low-temperature storage tanks and transport containers, and the connection method is completed through conventional welding technology. However, whether the new low-temperature steel has a relatively wide welding process window, whether the joint performance, especially the low-temperature impact toughness of the welded joint can reach the standard or user requirements, is the first time that the steel product enters the market. became the second condition. As can be seen from this, applying the submerged arc welding welding process of low-cost Ni-saving low-temperature steel to ensure that the mechanical performance of the welded joint meets the requirements is important for the safe use of the structure. and have practical significance.

The present invention provides a welding wire for submerged arc welding of Ni-saving low-temperature steel for cryogenic environments in order to solve the above technical problem.

The invention was created to solve the above technical problem, and its purpose is to provide a submerged arc welding welding wire of Ni-saving low-temperature steel for cryogenic environments, the chemical composition and mass percentage of which are as follows Similarly, C: 0.01% to 0.10%, Mn: 2.0% to 4.5%, Si: 0.10% to 0.20%, S≤0.01%, P≤0.02%, Ni: 9.0% to 15.0%, Cr: 10.0% to 16.0 %, Mo≤0.01%, V≤0.01%, remaining Fe and unavoidable impurities.

Technical effect: The welding wire of submerged arc welding of low-cost Ni-saving low-temperature steel for cryogenic environments designed by the present invention ensures that the metal and base material are matched as much as possible in the welded seam, and the -101℃ low-temperature impact toughness of the welded seam ≥34J and weld wire tensile strength ≥530MPa.

By the technical solution further limited by the present invention,

The chemical composition and mass percentage of the steel sheet to which the welding wire of the submerged arc welding of the Ni-saving low-temperature steel for the cryogenic environment is applied is as follows: C: 0.03% to 0.08%, Si: 0.05% to 0.20%, Mn: 0.85% ~ 1.75%, Ni: 0.85% ~ 1.25%, Mo ≤ 0.20%, Al: 0.015% ~ 0.06%, P ≤ 0.010%, S ≤ 0.002%, the balance is composed of Fe and unavoidable impurities.

The welding wire for submerged arc welding of the Ni-saving low-temperature steel for the cryogenic environment is suitable for a steel plate having a thickness of 20 to 35 mm.

In the welding wire for submerged arc welding of the Ni-saving type low-temperature steel for the cryogenic environment, the diameter of the welding wire Φ is 1.2 to 4.0 mm.

Another object of the present invention is to provide a welding process of a welding wire for submerged arc welding of Ni-saving type low-temperature steel for a cryogenic environment, which is,

It is a groove type symmetrical to an X-shaped groove at an angle of 52 to 62 degrees;

No preheating before welding, interlayer temperature ≤ 120 ° C, back chipping treatment before welding the back side;

It is a welding process using submerged arc welding.

In the welding process of the welding wire of the submerged arc welding of the Ni-saving low-temperature steel for the cryogenic environment, the root face size of the groove is 0 to 2 mm, and a gap of 0 to 3 mm is left before assembling the groove.

In the welding process of the welding wire of the submerged arc welding of the Ni-saving type low-temperature steel for the cryogenic environment, the welding current is 350 to 450A, the electric arc voltage is 25 to 37V, the welding speed is 28 to 38cm/min, and the welding The heat input is 18 to 36 kJ/cm.

The present invention achieves the following advantageous effects.

(1) The steel sheet applied in the present invention has yield strength ≥ 355 MPa, tensile strength ≥ 490 MPa, elongation ≥ 22%, and -101 ° C impact energy KV ₂ ≥ 80 J, for this type of steel sheet welded Design the wire and welding process to ensure the metal and heat affected zone structure and mechanical performance in the welded seam;

(2) The welding wire used in the present invention and the welding seam obtained by the welding process have excellent overall mechanical performance, -101 ° C impact energy KV ₂ ≥ 34J in the weld seam and heat-affected zone, and tensile strength Rm ≥ 490 MPa; Only the welding seam side is acceptable as d=4a, 180°;

(3) The weld seam formed by the welding process used in the present invention obtains good overall mechanical performance, can be applied to the production and welding of steel plates made of Ni-saving low-temperature steel with a thickness of 20 to 35 mm, and is easy to operate; It has advantages such as wide application environment and high economic feasibility.

1 is an explanatory view of a welding groove according to the present invention.

The following examples are all C: 0.03% to 0.08%, Si: 0.05% to 0.20%, Mn: 0.85% to 1.75%, Ni: 0.85% to 1.25%, Mo≤0.20%, Al: 0.015% to 0.06%, Applied to steel sheets composed of P≤0.010%, S≤0.002%, residual Fe and unavoidable impurities.

Example 1

In the welding process of submerged arc welding of Ni-saving low-temperature steel for cryogenic environments provided in this embodiment,

The steel plate thickness is 20 mm, the welded test plate combination is 20 mm + 20 mm, and the test plate size is 600 mm (rolling direction) × 180 mm (plate width direction) × 20 mm (thickness). The performance of the base material is yield strength ≥ 390 MPa, tensile strength ≥ 490 MPa, elongation ≥ 22%, and impact energy KV ₂ ≥ 80 J at -101 ° C.

The used welding wire has a diameter of 2.0 mm, and the chemical composition and mass percentage are as follows: C: 0.05%, Mn: 2.6%, Si: 0.13%, S: 0.001%, P: 0.009%, Ni: 13.8%, It consists of Cr: 10.5%, Mo: 0.005%, V: 0.001%, the balance of Fe and unavoidable impurities.

The groove type of the welding wire is an X-shaped groove, the groove angle is 53°, there is no root face, and the assembly clearance of the groove is 0.5mm; without preheating before welding, the interlayer temperature is 80 to 110°C; Back chipping treatment is performed with a grinder before welding the back side, and the root is configured to make the metal shiny; A welding process of performing submerged arc welding with a plurality of wires is used, the welding current is 381 A, the electric arc voltage is 30 V, the welding speed is 38 cm/min, and the welding heat input is 18 kJ/cm.

Example 2

In the welding process of submerged arc welding of Ni-saving type low-temperature steel for cryogenic environment provided in this embodiment,

The steel plate thickness is 20 mm, the welded test plate combination is 26 mm + 26 mm, and the test plate size is 600 mm (rolling direction) × 180 mm (plate width direction) × 26 mm (thickness). The performance of the base material is yield strength ≥ 390 MPa, tensile strength ≥ 490 MPa, elongation ≥ 22%, and -101 ° C impact energy KV ₂ ≥ 80 J.

The used welding wire has a diameter of 2.0 mm, and the chemical composition and mass percentage are as follows: C: 0.05%, Mn: 2.6%, Si: 0.13%, S: 0.001%, P: 0.009%, Ni: 13.8%, It consists of Cr: 10.5%, Mo: 0.005%, V: 0.001%, the balance of Fe and unavoidable impurities.

The groove form is X-groove, the groove angle is 58°, the root surface is 1mm, and the assembly clearance of the groove is 1mm; without preheating before welding, the interlayer temperature is 80 to 110°C; Before welding the back side, the back side is leveled with a grinder, and the root is configured to make the metal shiny; A welding process of performing submerged arc welding with a plurality of wires is used, the welding current is 420A, the electric arc voltage is 35V, the welding speed is 35cm/min, and the welding heat input is 25kJ/cm.

Example 3

In the welding process of submerged arc welding of Ni-saving type low-temperature steel for cryogenic environment provided in this embodiment,

The steel plate thickness is 35 mm, the welded test plate combination is 35 mm + 35 mm, and the test plate size is 600 mm (rolling direction) × 180 mm (plate width direction) × 35 mm (thickness). The performance of the base material is yield strength ≥ 390 MPa, tensile strength ≥ 490 MPa, elongation ≥ 22%, and -101 ° C impact energy KV ₂ ≥ 80 J.

The used welding wire has a diameter of 2.4 mm, and the chemical composition and mass percentage are as follows: C: 0.05%, Mn: 2.7%, Si: 0.11%, S: 0.001%, P: 0.008%, Ni: 14.3%, It is composed of Cr: 11.6%, Mo: 0.005%, V: 0.001%, the balance of Fe and unavoidable impurities.

The groove type is an X-shaped groove, the groove angle is 60°, the root face is 1mm, and the assembly clearance of the groove is 2mm; without preheating before welding, the interlayer temperature is 90 to 120°C; Before welding the back side, the back side is leveled with a grinder, and the root is configured to make the metal shiny; Using a welding process of performing submerged arc welding with a plurality of wires, the welding current is 450A, the electric arc voltage is 36V, the welding speed is 28cm/min, and the welding heat input is 35kJ/cm.

Mechanical performance tests were performed on the welded joints of Examples 1, 2 and 3, and the results are shown in the table below.

As can be seen from this, the overall mechanical performance of the welded seam obtained in the examples is excellent, the tensile strength of the welded seam is Rm≥520MPa, the welded seam side only is d = 4a, 180°, which is acceptable, and the weld seam and heat effect -101 ℃ impact energy KV ₂ of the region ≥46J.

The welding wire and welding process designed by the present invention are simple in implementation, highly applicable, and present a new direction for selecting low-cost, high-performance materials, so that low-cost Ni-saving low-temperature steel can replace 3.5Ni steel. , so that it can be widely used for drying storage transportation equipment used in cryogenic environments.

The present invention may be implemented in other embodiments than the above embodiments. All technical solutions formed by equivalent substitution or equivalent transformation are included in the protection scope claimed by the present invention.

Claims (7)

In the welding wire of submerged arc welding of Ni-saving type low-temperature steel for cryogenic environment,
Its chemical composition and mass percentage are as follows:
C: 0.01% to 0.10%, Mn: 2.0% to 4.5%, Si: 0.10% to 0.20%, S≤0.01%, P≤0.02%, Ni: 9.0% to 15.0%, Cr: 10.0% to 16.0%, A welding wire for submerged arc welding of Ni-saving low-temperature steel for cryogenic environments, characterized in that it is composed of Mo≤0.01%, V≤0.01%, residual Fe and unavoidable impurities. According to claim 1,
The chemical composition and mass percentage of the steel sheet to be applied are as follows,
C: 0.03% to 0.08%, Si: 0.05% to 0.20%, Mn: 0.85% to 1.75%, Ni: 0.85% to 1.25%, Mo≤0.20%, Al: 0.015% to 0.06%, P≤0.010%, A welding wire for submerged arc welding of Ni-saving low-temperature steel for a cryogenic environment, characterized in that it consists of S≤0.002%, a residual amount of Fe and unavoidable impurities. According to claim 2,
A welding wire for submerged arc welding of Ni-saving low-temperature steel for cryogenic environments, characterized in that it is suitable for steel plates having a thickness of 20 to 35 mm. According to claim 1,
A welding wire for submerged arc welding of Ni-saving low-temperature steel for a cryogenic environment, characterized in that the diameter of the welding wire is 1.2 to 4.0 mm. In the welding process of the welding wire of the submerged arc welding of the Ni-saving low-temperature steel for the cryogenic environment according to any one of claims 1 to 4,
It is a groove type symmetrical to an X-shaped groove at an angle of 52 to 62 degrees;
No preheating before welding, interlayer temperature ≤ 120 ° C, back chipping treatment before welding the back side;
A welding process of a welding wire of submerged arc welding of Ni-saving low-temperature steel for a cryogenic environment, characterized in that it is a welding process using submerged arc welding. According to claim 5,
Welding process of submerged arc welding of Ni-saving low-temperature steel for cryogenic environments, characterized in that the root face size of the groove is 0 to 2 mm and a gap of 0 to 3 mm is left before assembling the groove. According to claim 5,
Ni-saving low-temperature steel submerger for cryogenic environments, characterized in that the welding current is 350 to 450A, the electric arc voltage is 25 to 37V, the welding speed is 28 to 38cm/min, and the welding heat input is 18 to 36kJ/cm The welding process of the welding wire of de-arc welding.

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