阅读说明：本技术 一种双相不锈钢和超级奥氏体不锈钢异种钢的焊接方法 (Welding method for dissimilar steel of duplex stainless steel and super austenitic stainless steel ) 是由 张亮 许久海 安宏宇 张路宽 于 2020-11-24 设计创作，主要内容包括：本发明公开了一种双相不锈钢和超级奥氏体不锈钢异种钢的焊接方法,方法包括以下步骤：机加工坡口、坡口组队、定位焊接、打底焊接、填充焊接、反面清根、封底焊接和盖面焊接；方法采用CO-2药芯焊丝气体保护焊进行焊接,并采用多层多道焊接,焊接过程中彻底清除每道之间的焊渣和氧化物。通过坡口角度及接头形式设计、选用合理的焊接材料,有效避免了焊接母材对焊缝组织的稀释,使得靠近超级奥氏体904L一侧尽量产生较多的奥氏体组织,提高抗腐蚀性。另外通过选用合理的焊接材料,使焊缝接头能够具有足够的Cr、Ni、Mo等抗腐蚀性和细化晶粒的元素,降低焊接成本。(The invention discloses a welding method of dissimilar steel of duplex stainless steel and super austenitic stainless steel, which comprises the following steps: machining a groove, forming a group of grooves, positioning welding, backing welding, filling welding, back side back gouging, back sealing welding and cover surface welding; the method adopts CO 2 The flux-cored wire is welded by gas shielded welding, and adopts multilayer and multi-pass welding, and welding slag and oxides between every two passes are thoroughly removed in the welding process. By designing the bevel angle and the joint form and selecting reasonable welding materials, the dilution of welding parent metal to welding seam tissues is effectively avoidedSo that the side close to the super austenite 904L generates more austenite structures as much as possible, and the corrosion resistance is improved. In addition, by selecting reasonable welding materials, the welding joint can have enough Cr, Ni, Mo and other corrosion resistance and elements for refining grains, and the welding cost is reduced.)

1. A welding method of dissimilar steels of duplex stainless steel and super austenitic stainless steel is characterized by comprising the following steps:

1) groove machining, wherein the groove angle of the machined duplex stainless steel is alpha, and the groove angle of the machined super austenitic stainless steel is beta;

2) according to the form of a weld joint, pairing two dissimilar steel groups to be processed, wherein the root gap between the two dissimilar steel groups is h & lt 3-4 mm;

3) tack welding, i.e. tack welding: the protective gas flow is 12-15L/min, the welding current is 150-;

4) backing welding, namely backing weld: the protective gas flow is 12-15L/min, the welding current is 150-;

5) fill welding, i.e. a filler weld: the flow of protective gas is 12-15L/min, the welding current is 150-;

6) back side back chipping, wherein back side back chipping is carried out in a polishing mode, and oxide skin is thoroughly removed;

7) back cover welding, namely welding of a back cover layer: the protective gas flow is 12-15L/min, the welding current is 150-;

8) cover welding, namely cover welding seam: the protective gas flow is 12-15L/min, the welding current is 150-.

2. The welding method according to claim 1, characterized in that: the duplex stainless steel is SS2205, the super austenitic stainless steel is 904L, alpha is 30-50 degrees, beta is 10-30 degrees, and alpha + beta forms a 60-degree V-shaped groove.

3. The welding method according to claim 1 or 2, characterized in that: α is 45 ° and β is 15 °.

4. The welding method according to claim 1, characterized in that: welding is carried out by CO2 flux-cored wire gas shielded welding.

5. The welding method according to claim 4, characterized in that: the chemical composition and mechanical property of the welding wire meet the AWS A5.22E 2209T1-1 grade standard, and the diameter of the welding wire is 1.2 mm.

6. The welding method according to claim 1, characterized in that: the welding method adopts multilayer multi-pass welding, and welding slag and oxides between every two passes are thoroughly removed in the welding process.

7. The welding method according to claim 6, characterized in that: the inter-track temperature of the welding does not exceed 100 ℃.

Technical Field

The invention relates to a welding technology, in particular to manufacturing of a marine desulfurization tower component, and particularly relates to a welding method of dissimilar steel of duplex stainless steel and super austenitic stainless steel.

Background

With the increasing approach of the strict implementation period of pollutant emission standards of national and international organizations such as IMO, European Union, United states and the like, the development of ship tail gas desulfurization devices is carried out by various ship engine manufacturers and ship pollution reduction equipment manufacturers all over the world, so as to reduce the ship fuel cost and the operation cost under the condition of meeting the pollutant emission limit.

The using environment of the desulfurizer EGCS is filled with high-concentration alkaline liquor NaoH, the temperature of the tail gas of the diesel engine is generally more than 200 ℃, and extremely high requirements are put forward on the material of the desulfurizing tower in the high-temperature and high-alkalinity environment. At present, the material of the desulfurizing tower is mainly duplex stainless steel SS2205, super austenitic stainless steel 904L, nickel-chromium-molybdenum alloy 254SMo and other materials. In terms of raw material cost, the duplex stainless steel SS2205 has the lowest unit price, the super austenitic stainless steel 904L times and the nickel-chromium-molybdenum alloy 254SMo have the highest price. Although the unit price of the duplex stainless steel SS2205 is low, the corrosion resistance of 904L or 254SMo can be achieved only by increasing the thickness in the design process, and the comprehensive cost is high. In order to save the manufacturing cost, the mixed material is adopted in design so as to achieve the balance of use strength and corrosion resistance. The duplex stainless steel SS2205 and the super austenitic stainless steel 904L are main structural materials, the strength of the duplex stainless steel SS2205 is about 2 times that of the common austenitic stainless steel 316L, and the duplex stainless steel has good corrosion resistance. The super austenitic stainless steel 904L has excellent high-temperature corrosion resistance, and thus is mainly applied to the air inlet of the desulfurization tower and the washing liquid collecting part. However, the duplex stainless steel SS2205 and the super austenitic stainless steel 904L have different structures and chemical compositions, so that the actual welding has great difficulty. In the field of marine desulfurization units, there is currently no particularly well-established welding method for the two materials SS2205 and 904L.

Disclosure of Invention

In order to overcome the disadvantages of the prior art, the present invention aims to provide a welding method for dissimilar steels of duplex stainless steel and super austenitic stainless steel, which can solve the above problems.

The purpose of the invention is realized by adopting the following technical scheme:

a welding method of duplex stainless steel and super austenitic stainless steel dissimilar steel comprises the following steps:

1) and (3) performing groove processing on the duplex stainless steel SS2205 and the super austenitic stainless steel 904L, wherein the groove processing adopts a mechanical mode. The bevel angle on the SS2205 side is 45 degrees, the bevel angle on the 904L side is 15 degrees, and the two form a 60-degree bevel.

2) And (4) assembling the two parts according to the form of the weld joint, wherein the root gap between the two parts is 3-4 mm.

3) And (6) positioning and welding.

4) And (7) backing welding.

5) And (5) filling and welding.

6) Back side back chipping

7) And (7) bottom sealing and welding.

8) And (7) welding the cover surface.

Preferably, CO is used₂Gas shielded welding (FCAW) is used for welding.

Preferably, the welding method adopts multilayer multi-pass welding, and welding slag and oxides between every two passes are thoroughly removed in the welding process.

Preferably, the inter-track temperature of the weld does not exceed 100 ℃.

Preferably, the weldment formed by the dissimilar steel welding method is manufactured by welding a desulfurizing tower device (EGCS) for a ship.

Compared with the prior art, the invention has the beneficial effects that: through the design of the bevel angle and the joint form and the selection of reasonable welding materials, the dilution of welding parent metal to a welding seam structure is effectively avoided, so that more austenite structures are generated on one side close to the super austenite 904L as much as possible, and the corrosion resistance is improved. In addition, by selecting reasonable welding materials, the welding joint can have enough Cr, Ni, Mo and other corrosion resistance and elements for refining grains, and the welding cost is reduced.

Drawings

FIG. 1 is a schematic diagram of groove design of two dissimilar steels;

fig. 2 is a schematic diagram of a multi-layer welding bead in two dissimilar steel welding processes.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

A welding method of duplex stainless steel and super austenitic stainless steel dissimilar steel comprises the following steps:

1) and (3) groove machining, referring to fig. 1, wherein the groove angle of the machined duplex stainless steel is alpha, and the groove angle of the machined super austenitic stainless steel is beta.

The duplex stainless steel is SS2205, the super austenitic stainless steel is 904L, alpha is 30-50 degrees, beta is 10-30 degrees, and alpha + beta forms a 60-degree V-shaped groove.

In one embodiment, α is 45 ° and β is 15 °.

2) According to the form of the weld joint, the root gap between two dissimilar steel groups to be processed is 3-4 mm.

3) Tack welding, i.e. tack welding: the protective gas flow is 12-15L/min, the welding current is 150-.

4) Backing welding, namely backing weld: the protective gas flow is 12-15L/min, the welding current is 150-.

5) Fill welding, i.e. a filler weld: the protective gas flow is 12-15L/min, the welding current is 150-.

6) And back side back chipping, wherein back side back chipping is carried out by adopting a polishing mode, and oxide skin is thoroughly removed.

7) Back cover welding, namely welding of a back cover layer: the protective gas flow is 12-15L/min, the welding current is 150-.

8) Cover welding, namely cover welding seam: the protective gas flow is 12-15L/min, the welding current is 150-.

The welding method in the scheme adopts CO₂And welding by flux-cored wire gas shielded welding. Wherein, the chemical composition and the mechanical property of the welding wire meet the AWS A5.22E 2209T1-1 grade standard, and the diameter of the welding wire is 1.2 mm.

Referring to fig. 2, the welding method adopts multilayer multi-pass welding, and welding slag and oxides between every two passes are thoroughly removed in the welding process.

In the welding process, the temperature between welding channels is not more than 100 ℃.

By adopting the welding process scheme between the duplex stainless steel and the super austenitic stainless steel, the weld joint is an austenitic ferrite structure, wherein ferrite is less on the side close to 904L and more on the side close to SS2205, and austenite is opposite. The welding method can obtain the welding joint meeting the technical requirements of the EGCS desulfurizing tower, and can be applied to the welding manufacture of the EGCS device.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.