CN100500363C - Method for preparing low hydrogen type downwards electrode - Google Patents

Abstract

The invention discloses a process for preparing hydrogen-controlled downwards electrodes. Steel wires H08E are used as a welding core, and explosive cartridge weight is 35-50% of the welding electrode weight. The percentage by weight of the invention is that CaCO3 is 25-38%, TiO2 is 10-20%, CaF2 is 12-20%, SiO2 is 5-10%, and Al2O3 is 3-6%. 8-15% ferrous alloy and 10-18% pure metal powder are added to meet the demand of the deposited metal rigidity and low-temperature flexibility. The electrodes have outstanding downward technology operational property, the welding positions, including flat, vertical and backstroke and the like, keep a metallic molten pool to be clean, and molten slag can not drip. The tensile strength of the weld metal is equal or more than 550 MPa, the ballistic work under the low-temperature of below 20 DEC G is more than 100 J, and the diffusible hydrogen content is less than 5 ml per 100 grams. The invention is adaptable for the welding of X42-X65 of API standard or other tube steel with equal rigidity grade, and is also suitable for the integral-position welding of pressure containers, ships, engineering machinery or other important structures, and the like.

Description

A kind of low hydrogen type downwards electrode

Technical field:

The invention belongs to technical field of welding materials, specially refer to a kind of low hydrogen type downwards electrode.

Background technology:

Along with China's development of oil, natural gas line construction in recent years, the down hill welding connection technology obtains promotion and application promptly, especially in pipeline or the welding of pressure vessel circular weld, down hill welding connects as shown in Figure 1 relatively, and up hill welding connects as shown in Figure 2, it is raised the efficiency more than 30%, and welding rod consumption reduces 30%～50%.Yet down hill welding connects technology the all-position welding operability of welding rod itself has been proposed very high requirement: it is clear to remain the molten bath in welding positions such as putting down, stand, face upward, does not drop down slag; Welding arc will have suitable blow force of arc to help appearance of weld.

The welding of major diameter, high strength, big wall thickness pipeline or container, the low-temperature flexibility of butt welded seam metal, cracking resistance have also proposed high requirement, what the welding use under these conditions was more is hydrogen controlled electrode, but traditional hydrogen controlled electrode is because the characteristics of welding rod slag, can only adopt up hill welding to connect the method welding, drop down under the slag when being used for down hill welding and connecing, be difficult to welding.

Summary of the invention:

For solving above-mentioned existing problem, the present invention proposes a kind of low hydrogen type downwards electrode, make appearance of weld good, weld metal tensile strength 〉=550MPa,-20 ℃ of low-temperature impact works are greater than 100J, gas chromatography records its diffusible hydrogen content and is lower than 5ml/100g, reaches international ultralow hydrogen brazing material index request.

For achieving the above object, the present invention adopts following technical scheme:

Described low hydrogen type downwards electrode, its core wire adopts the H08E steel wire, outer coated coating, coating weight accounts for 35～50% of welding rod weight;

Electrode coating is formed and percentage by weight:

CaCO ₃25～38%, TiO ₂10～20%, CaF ₂12～20%, SiO ₂5～10%, Al ₂O ₃3～6%; Ferroalloy 8～15%, pure metal powder 10～18%;

In the component of described ferroalloy 8～15%; Ferrotianium 4～7%, ferrosilicon 4～6%, molybdenum-iron 0～2%;

In the component of described pure metal powder 10～18%; Nickel powder 0～1%, manganese powder 2～8%, iron powder 7～10%.

Because adopt aforesaid technical scheme, the present invention has following good effect:

Among the present invention, CaCO ₃Be a kind of main component of coating, the effect that increases blow force of arc, regulates the slag physicochemical characteristic arranged, CaCO ₃Addition 25～38%; CaCO ₃Be less than at 25% o'clock, blow force of arc is not enough, easily causes to drop down the slag phenomenon, is unfavorable for the down hill welding operation; Addition surpasses at 38% o'clock, and blow force of arc is too big, and arc stability is bad, and spatter sharply increases, the appearance of weld variation.

Among the present invention, TiO ₂Help to improve the arc stability of welding rod, can reduce spatter, help the removability of slag, TiO ₂Add with rutile form, its addition is 10～20%; When addition surpassed 20%, the weld seam oxygen content improved, and has reduced low-temperature flexibility; Addition is lower than at 10% o'clock, and welding procedure is relatively poor, and when particularly standing weldering downwards, appearance of weld is not good.

Among the present invention, CaF ₂Be dehydrogenation material in the compositions of surfacing metal, under the arc atmosphere condition, CaF ₂With SiO ₂And TiO ₂Generate SiF Deng reaction ₄And TiF ₄Gas can reduce the dividing potential drop of hydrogen in the arc region effectively, reaches the effect of dehydrogenation; Except dehydrogenation, also can regulate the viscosity of welding slag, and help to improve the covering power of slag, CaF ₂Addition is 12～20%; When addition was less than 12%, the dehydrogenation of welding rod descended; Addition surpasses at 20% o'clock, causes the coating fusing point low excessively, and viscosity coefficient of dross reduces, and the letter of welding rod cover is too short, and the power of blowing reduces, and is prone in the downward welding in the vertical position process and drops down slag, and holder is the phenomenon of molten iron incessantly.

Among the present invention, SiO ₂Have the refinement molten drop, reduce the effect of splashing, improve processing performance, SiO ₂Addition 5～10%; SiO ₂Be less than at 5% o'clock, not obvious to the improvement effect of processing performance; Addition surpasses at 10% o'clock, and removability of slag variation reduces the toughness of weld seam simultaneously.

Among the present invention, Al ₂O ₃Fusing point is higher, and the effect of adjusting the slag fusing point is arranged in electrode coating, has suitable setting temperature with making slag cooperating of other compositions, and slag can solidify any more rapidly and drops down Al in the down hill welding operation ₂O ₃Addition 3～6%; It is not obvious to be less than the effect of adjusting slag at 3% o'clock; Addition surpasses at 6% o'clock, occurs defectives such as pore or welding bead load mould easily.

Among the present invention, in order to guarantee the mechanical property of welding wire deposited metal, particularly intensity and low-temperature flexibility, the present invention also adds various ferroalloys in electrode coating, as ferrotianium, ferrosilicon and molybdenum-iron, mainly as the deoxidier and the alloying constituent of weld seam, its addition is 8～15%.

Among the present invention, also added pure metal powder 10～18% in the electrode coating, they mainly are metal iron powder, metallic nickel and manganese metal, the adding of metal iron powder is in order to improve the deposition efficiency of down hill welding, be in order to adjust the alloying component of weld metal adding as alloying constituent of metallic nickel and manganese metal.

Its mechanical property of hydrogen controlled electrode of the present invention sees the following form:

Its diffusible hydrogen content of hydrogen controlled electrode of the present invention sees the following form:

Its distinguishing feature is as follows:

1, this alkaline low-hydrogen type down hill welding bar has good downward welding technology performance, does not all drop down slag putting down, stand, face upward each position when down hill welding connects, and it is clear to remain the molten bath, and arc burning is stable, and it is easy to take off slag, and appearance of weld is good.

2, this alkaline low-hydrogen type down hill welding bar, the tensile strength of its deposited metal can reach more than the 550MPa, and good low-temperature impact toughness is arranged, and-20 ℃ of low-temperature impact works can be used in the welding of cold district high strength, high tenacity pipe line steel greater than 100J.

3, this alkaline low-hydrogen type down hill welding bar, gas chromatography records its deposited metal diffusible hydrogen content and is lower than 5ml/100g, reaches international ultralow hydrogen brazing material index request, and be used for big wall: the welding of thick structure has good anti-cold cracking ability.

4, this alkaline low-hydrogen type down hill welding bar adopts down hill welding to connect the technology welding and connects technology than traditional up hill welding and raise the efficiency more than 30%, and welding rod consumption reduces 30%～50%.

5, this alkaline low-hydrogen type down hill welding bar, its raw material are purchased easily, and cost is lower, manufacturing is easy, can reduce use cost.

6, this alkaline low-hydrogen type down hill welding bar, it is applicable to the welding of the pipe line steel of API X42～X65 or other suitable intensity rank, also can be used for the all-position welding of other important structure such as pressure vessel, boats and ships, engineering machinery.

Description of drawings:

Fig. 1 is a down hill welding bar schematic diagram:

Fig. 2 is the up hill welding bar schematic diagram of ordinary circumstance pipeline:

The specific embodiment:

Embodiment one;

This low hydrogen type downwards electrode, its core wire adopt commercially available H08E steel wire, and outer coated coating becomes welding rod, and coating weight accounts for welding rod weight 35～50%;

In its coating: CaCO ₃25%, TiO ₂20%, CaF ₂17%, SiO ₂7%, Al ₂O ₃5%, ferrotianium 4%, ferrosilicon 4%, manganese powder 8%, iron powder 10%.

Embodiment two:

This low hydrogen type downwards electrode, its core wire adopt commercially available H08E steel wire, and outer coated coating becomes welding rod, and coating weight accounts for welding rod weight 35～50%;

In its coating: CaCO ₃33%, TiO ₂10%, CaF ₂20%, SiO ₂5%, Al ₂O ₃6%, ferrotianium 5%, ferrosilicon 4%, molybdenum-iron 1%, nickel powder 1%, manganese powder 6%, iron powder 9%.

Embodiment three:

This low hydrogen type downwards electrode, its core wire adopt commercially available H08E steel wire, and outer coated coating becomes welding rod, and coating weight accounts for welding rod weight 35～50%;

In its coating: CaCO ₃38%, TiO ₂12%, CaF ₂12%, SiO ₂10%, Al ₂O ₃3%, ferrotianium 7%, ferrosilicon 6%, molybdenum-iron 2%, nickel powder 1%, manganese powder 2%, iron powder 7%.

Claims (1)

1, a kind of low hydrogen type downwards electrode, core wire adopts the H08E steel wire, and outer coated coating is characterized in that: its coating weight accounts for welding rod weight 35～50%;

Electrode coating is formed and percentage by weight:

CaCO ₃25～38%, TiO ₂10～20%, CaF ₂12～20%, SiO ₂5～10%, Al ₂O ₃3～6%; Ferroalloy 8～15%, pure metal powder 10～18%;

In described 8～15% the ferroalloy; Ferrotianium 4～7%, ferrosilicon 4～6%, molybdenum-iron 0～2%;

In described 10～18% the pure metal powder; Nickel powder 0～1%, manganese powder 2～8%, iron powder 7～10%.

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