DE2346873A1 - PROCESS FOR IMPROVING THE VALUES OF THE HEAT INFLUENCE ZONE - Google Patents

Description

KNIVES GSIESHEIM GMBH -MG

Password: deposition welding-melting Inventor: Dr «, Austel, Dr. Ruckdeschel, bone.

Process for improving the quality values of the heat affected zone

The invention "relates to a method for improving the Quality values of the heat affected zone in the manufacture of coated Surfaces by Schinelz build-up welding, in particular with submerged powder build-up welding with strip electrodes made of Fi alloys or Cr-H "i-steel and with Plasma hot-wire build-up welding on steel components.

A number of welding processes for producing melt deposits are already in use today on an industrial scale. I ^{1 For} smaller deposits, a gas flame is used as a heat source to melt the base material and to melt the filler material to be applied. Overlay welding with stick electrodes can also be carried out by hand. Among the welding processes that can be carried out mechanically, in particular build-up welding with an arc burning under protective gas and a melting electrode as well as one or more additionally supplied wires as filler material (so-called MIG build-up welding with cold wire filler), arc build-up welding under welding powder with a strip electrode and, more recently, the so-called. Plasma hot-wire build-up welding has become important. In the latter process, a plasma arc is used as the heat source for melting the base material

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ensures, while two mechanically supplied, connected to a power source, under Kurzsohlußberkontakt with the workpiece Wires that melt in the arc region supply the material for the application. *

Submerged arc deposition welding with strip electrodes is of particular importance in the manufacture of pressure vessels and primary circuit components of nuclear reactors, of containers for the wholesale chemistry as well as for others components subject to corrosion and pressure. The heating of the base material associated with overlay welding however, it leads to disadvantageous changes in these steels. These processes in steel can under certain conditions, which today have not yet been clarified in detail, especially in the heat affected zone of the base material, on the origin of cracks (so-called underplating cracks). The formation of these cracks must, however, be avoided at all costs as these micro-cracks can lead to breakage when the component is exposed to operational stress can.

It is known that the risk of underneath. The heating of the base material associated with the application of the second layer then serves to encircle the heat-affected zone created by the first layer. However, this method, previously used in submerged powder build-up welding with a strip electrode, has the disadvantage that the thickness of the build-up must be increased by a second layer for the purpose of re-graining the heat-affected zone of the base material. This increase in. Application thickness causes considerable additional costs , as more additional tools

^ coarse-grained sheet of the

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material of the corresponding, mostly high-alloy, 'corrosion-resistant' '' alloy, from which the plot consists, must be used.

* ■

The object of the present invention is therefore to create a method for improving the quality values of the heat affected zone, which the above Does not have any disadvantages.

The invention consists in that over the applied surface layer oscillating an arc with a non-melting electrode is guided in such a way that the energy of the arc only part of the surface layer melts and that continues to divide the advancing speed of the arc is smaller than the diameter of the arc at the point of its largest diameter due to the pendulum frequency.

The inventive remelting of a single-layer build-up weld with an arc, when using the o. g. The parameter becomes the heat affected zone of the base material improved so that no under seam cracks occur. Also leads the method according to the invention does not lead to any deterioration in the surface quality of the plating surface, because if it is adhered to the parameter is advantageously avoided that by the movement of the arc and by the surface tension of the liquid metal creates concave or convex bumps on the surface. So there are advantageously no dents, which lead to a weakening of the cladding layer and no stools that make the ultrasonic testing of the cladding difficult, on.

These demands, which are difficult to reconcile, for a correspondingly uniform and one hundred percent grain size the heat-affected zone of the base material and at the same time a smooth surface of the melted ■ Plating are achieved by the method according to the invention »in particular by the fact that the arc in spite of the

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Pendulum movement covers the full application area. In an advantageous further education the invention it is proposed for this purpose that the pendulum frequency is approximately in the range of 0.5 to 4.0 Hz, preferably 0.8 to 2.0 Hz and the preceding · « feed speed is approximately in the range from 0.1 to 0.6 m / min, preferably 0.1 to 0.3 m / min. If you comply with this Values will be a good graining effect as well as a smooth surface of the plating, especially in the case of plasma hot wire - Obtained on contract welding and submerged powder build-up welding with strip electrode.

According to a further proposal of the invention, the Energy of the arc applied to the surface layer

Melted in such a way that between the upper surface of the base material and the lower limit of the re-melted Z distance of not less than 0.5 mm and not more than 4.0 mm, preferably a distance between 1 and 3 mm y, remains. This ensures that when the surface is melted again, the application melts again sufficiently deeply, but the base material is not melted. The melting depth can be changed by coordinating the welding current and welding voltage with the parameters of the arc movement. The values required for the type of application layer can be determined empirically. The values are set in such a way that advantageously a web of "\ ^" 0.5mm of the base material is not melted. The method according to the invention can be carried out both with a TIG arc torch and with a plasma arc torch. However, a plasma arc torch is preferably used, since the arc voltage of this torch can advantageously be used at the same time as a control variable for controlling the height of the torch from the cladding surface. This makes it possible to guide the plasma torch at a constant distance over the applied layer, which in turn is advantageous for the "surface quality". In addition, uniform melting can be achieved with a plasma torch.

··· -.- · ■. · ■ ■■: · Β09-8.2., 8 · /. 0-28-5. · ■. . · ■

To improve the surface quality, in particular to smooth the plating surface, it is proposed according to the invention that a filler material is added to the arc in an amount which results in a layer thickness that is not greater than the depth of melting. A layer thickness between 0.5 and 2.5 mm, preferably between 0.5 and 1.5 mm, is particularly advantageous. The filler material has a similar composition to the material of the application and is either blown into the arc as metal powder with the shielding gas flow or continuously fed to the arc in the form of one or more wires sideways from the permanent electrode.

Illustrated in the drawing

Fig. 1 is a section through a build-up weld

ßung
FIG. 2 shows a section along the line A - A in FIG.

In Figs. 1 and 2, the base material is with Io and the single-layer application layer designated with 11! The schematic The arc torch 12 shown is used to melt the zone 13 in the feed direction 14 at a constant distance 15 moves over the application layer 11 and performs at the same time a pendulum movement in the direction of the double arrow 16. The oscillation thus takes place transversely to the direction of application 17. The largest arc diameter is 18, the melting depth 19 and the remaining unmelted bar of the base material Io is denoted by 2o.

Possibly.

A filler material layer 21 applied during remelting for surface smoothing is shown in broken lines .

vThis usually consists of a large number of one another partially overlapping individual weld beads lying next to one another.

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ν - 6 -

Preferred parameters for carrying out the method according to the invention are given below in two examples:

example 1

Base material 10

Application method of the application layer

Band material = coating material

: Reactor material 22 Ni Mo Cr: UP tape plating

ι X 2 Cr Ni Nb'2412

Tape material,
Dimensions : 60 mm χ 0.5 m Thickness of the order
layer 11 ί a layer, 4 Width of the order
layer 23 : 63 mm Arc torch 12 : Plasma torch Arc current : 350 A Arc voltage : 40 V Arc gas ί Ar Arc feeders
speed 14 : 0.15 m / min Flat curve pendulum frequency 16 : 1.5 Hz Melting depth 19 ! 3.5 mm Bridge 20 1.5 mm Underclad cracks: no Example 2

Base material 10

Application method of the application layer

Application material

Deposition material dimension

Thickness of the application layer 11

Arc torch

: ST 42

ι Plasma hot-wire build-up welding

: X 2 Cr Ni Nb 2210

: 1.6 mm diameter electrodes

: one layer, 4 mm

: Plasma hot-wire build-up welding torch

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Arc torch current

Arc voltage arc gas, * -

Arc advance speed 14

Arc pendulum frequency 16

Additional work piece 21

Filler material melting depth 19 bar 20

Total build-up welding thick 22

Application layer width 23

Underclad cracks

450A 42.5V

Ar

0.18 m / min

0.8 Hz. 1 mm

X 2 Cr Ni Nb 2210 2.3mm 1.7mm 5mm 33mm no

The invention described above is preferably suitable for improving the quality values for inlay cladding. It is of course, however, it is also possible to improve multilayer cladding with the method according to the invention, whereby the reflow according to the invention is then carried out after the first and / or each subsequent individual plating will. In addition, it is of course also possible to have a plating that replaces the UP tape plating or plasma hot-wire build-up welding process was produced using any other process, to improve with the method according to the invention.

In addition, it is possible to set up an electric arc to use any other heat source, for example one Jthl

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Claims (1)

Expectations Process for improving the quality values of the heat-affected zone in the manufacture of coated upper and flat surfaces by fusion build-up welding, in particular in submerged powder build-up welding with a strip electrode made of Ni alloys and Cr-Ni steels and with plasma hot wire surfacing on steel components, thereby characterized in that an arc torch oscillating over the applied surface layer non-melting electrode is guided in such a way that that the energy of the arc melts only part of the applied surface layer and that furthermore the advancing speed of the arc divided by the pendulum frequency is less than that Diameter of the arc at the point of its largest Diameter. 2. The method according to claim 1, characterized in that the pendulum frequency is approximately in the range of 0.5 to 4.0 Hz, preferably 0.8 to 2.0 Hz and the feed rate approximately in the range from 0.1 to 0.6 m / min, preferably 0.1 to 0.3 m / min. 3. The method according to claim 1 or 2, characterized in that the applied by the energy of the arc Surface layer is melted in such a way that between the base material surface and the lower limit the reflow zone a distance of not less than 0.5 mm and not more than 4 mm, preferably a gap between 1 and 3 mm remains. ORDINAL INSPECTED 509 82.8 / 0 28 5 4. The method according to any one of claims 1 to 3 * characterized in that as an arc torch a; Plasma torch is used. 5. The method according to any one of claims 1 to 4,, characterized in that a filler material is fed to the arc, in an amount which results in a layer thickness that is not greater than the melting depth. 6. The method according to claim 5 * characterized in that the layer thickness is 0.5 to 2.5 mm, preferably 0.5 to 1.5 mm. 13.9.1973 ^{Be / Pu} ORIGINAL INSPECTED 5'-O982.8 / 0.285 4ο Blank page