RU1334548C - Protecting past composition - Google Patents

Abstract

FIELD: welding. SUBSTANCE: invention relates to welding production, in particular, to fusion arc welding of closed joints of end joints of non-alloy 1lims electrode, and can be used for sealing ampoules and welding of pipes with tube disks in power engineering. The purpose of the invention is to improve the quality of the welded joint by limiting the lateral sagging of the weld. To do this, the ingredients of the protective paste (P) of the required composition are weighed before welding, mixed and the mixture is diluted to a thick cream with a solvent. The resulting mass P is placed in the cavity of the plug and sealed using a hand press. The excess P from the edges of the ampoule body and the plug is removed with a knife. Then P was dried at room temperature to evaporate the solvent. The use of P limits lateral sagging of the weld due to an increase in its heat resistance and a decrease in the wettability of the weld pool by metal. In this case, refractory compounds of the metal being welded, for example, oxides, carbides, nitrides with a fineness of 0.256 dvsKc 0.56, where 6 is the tolerance for lateral sagging of the weld, microns, are used as powder P; dwaKc is the maximum particle diameter of nopousKa. microns. The solvent used is fast-evaporating alcohol, for example ethyl alcohol, with the following ratio of ingredients, May%: powder from refractory compounds of the welded metal 75-85, polyvinyl butyral 5-15, fast-evaporating alcohol solvent 8-18. 2 ill., 7 tab. SS OE СО 4 О1 4 00

Description

The invention relates to welding, in particular to arc welding by fusion of closed joints of end joints with a non-consumable electrode, and can be used in sealing ampoules and welding pipes with tube boards in power engineering.

The aim of the invention is to improve the quality of the welded joint by limiting the lateral sagging of the weld by increasing the heat resistance and reducing the wettability of the paste.

In FIG. 1 shows a diagram of filling a hole in a plug with a protective paste; ia FIG. 2 - node I in FIG. 1.

The following symbols are adopted in the drawing: I — ampoule body; 2 - a stub; 3 - protective paste; 4 - weld; 5 - binder film (polyvinyl butyral); b - tolerance for lateral sagging of the seam, microns; dnaKc is the maximum diameter of the powder particles, μm m.

Before welding, the ingredients of the protective paste of the required composition were weighed, mixed and the mixture was diluted to a thick sour cream with a solvent. The resulting mass of protective paste 1 was placed in the cavity of the plug 2 and sealed using a hand press. The sticky protective paste 3 from the edges of the ampoule housing 1 and the plug 2 was removed with a knife. Then, the protective NeNe paste was sieved at room temperature to evaporate the solvent. During the welding process, the refractory porous material entering the protective paste is wetted by the molten metal and is therefore easily separated from the surface of the weld.

With dnaKc 0.56, molten metal can flow between the particles of refractory powder to a depth of more than half the tolerance for lateral sagging of the seam (Fig. 2). At 0.256, finely divided fractions of the powder reduce the quality of the resulting compounds as a result of its particles entering the weld metal in the form of foreign inclusions.

When the amount of refractory powder in the protective paste decreases by less than 75%, its technological characteristics deteriorate: during the welding process, the polyvinyl butyral decomposes and the refractory powder crumbles, while the lateral sag of the seam increases beyond acceptable limits, and foreign inclusions appear in the weld.

If the amount of refractory powder in the protective paste increases by more than 85%, its electrical and technological characteristics are improved: the probability of arc excitation is reduced; the transition time during arc ignition and lateral sagging of the seam increases, and inclusions at nine also appear.

If the protective paste contains less than 5% polyvinyl butyral, its electrical characteristics noticeably worsen, especially the probability of arc excitation. Cro

In addition, technological indicators, namely, the adhesion of powder particles in the hardened mass, deteriorate, and the number of inclusions in the weld increases:

In case of presence in protective paste

 polyvinyl butyral more than 15% is worse than its technological (sagging of the weld seam increases) and exploitation. tational indicators (the amount of undissolved polyvinyl butyral in the mixture increases, as well as the drying time of the diluted paste). If the protective paste in the protective paste contains less than 8%, its technological characteristics deteriorate: the lateral sagging of the seam increases beyond the permissible limits due to the blowing out of the unconnected particles of refractory powder with argon, and in the weld seam, powder inclusions appear. In the case of an increase in the amount of solvent over 18%, the drying time of the diluted paste significantly increases, in addition, zero5

The mass is very liquid and it

it is difficult to fill the cavity.

Tests were carried out when welding butt welds of ampoules. Welding was performed on a CA-281 welding machine using protective pastes for various metals.

Before welding, the ingredients of the protective paste of the required composition were weighed out and diluted to a thick sour cream consistency with a solvent. The resulting mass was placed in a cavity and closed and compacted using a hand press. The excess protective paste was removed with a knife. The protective paste was then dried at room temperature to evaporate the solvent.

Q. Example I. The butt weld of an ampoule with a diameter of 6.0 X 0.3 was welded from VT4 alloy. According to technical requirements, the tolerance 6 on the internal lateral sagging of the seam for this product is 0.06 mm. As a refractory nopoujKa protective paste

5 used titanium carbide (Ti, C, Tm 3170 ° C) having a maximum particle diameter of 30, 20, 0 μm (in accordance with GOST 3584-73, powders of the following dispersions are produced: 180, 160, 125, 100, 80, 63. 56, 40 microns). Besides,

0 micropowders of particle sizes 30, 20, 10, 5 microns are produced. Samples were welded in the following mode: arc current 6 L, welding speed 20, arc length I mm.

After welding, the entertaining paste 3 (see Figs. 1 and 2) was removed from the cavity of the plug 2 and

5, using the microscope 2, the diameter of the plug hole after welding was measured. Metallographic and micro X-ray spectral spectra were also carried out in the characteristic radiation of an investigation of welded 111POV for the presence of

0.25b d ,, 0,

10

Note: cf 0.06 mm 60 μm

 given in table. 1 of the data it follows that (in order to obtain the required tolerance on the lateral force ujBa and the absence of inclusions in the weld, it is ensured when using refractory powder with a dispersion of 20 microns, i.e., when the ratio 0.256; dnaKc; 0.56 is satisfied.

Example 2. The butt weld of an ampoule with a diameter of 8.0 X 0.3 was welded from steel 12X18ShOT. The tolerance for lateral sagging of the seam 6 of this product is 0.10 mm. As a refractory powder of protective paste is56

0.25sU dMaxc 0.55

40 30 20

P

NOTE

From the data table. 2 it follows that obtaining the required tolerance for lateral sagging of the seam and the absence of inclusions in the welded joint is achieved when using a powder of chromium sulphate dispersed and e: 6 0

nii. Result {.1 .T (Miiif.ix and the most recent in tab. /. 1.

G b l and c;) 1

no inclusions

individual inclusions

They used chromium sesquioxide (СgoОл, Тp.1 2440 ° С) of the following dmperspersions: 56, 40, 30, 20 microns.

Samples were welded in the following mode: current. arc 12 A, welding speed - 15 m-h, arc length 1 mm. After welding, the protective paste was removed from the plug cavity and the amount of lateral sagging of the seam was determined. The results of visual, metallographic, x-ray microspectral studies of welded joints are presented in table. 2.

Table 1d a 2

102

no inclusions

89

74 59

separate including and

mm 100 μm

30 and 40 microns. those. the ratio of 0.25 () (1 "lux

3) The butt tone of ampoules with a diameter of 9.0 X 1.0 mm was welded from an alloy of Zr-f 1%.

technical requirements, the tolerance for lateral sagging (willow L. dp of this product is 0.14 mm. As a refractory powder of protective paste ps1 (zirconium nitride (ZrN, Tc. - 2982 C) was used) with the following disper sities: 30 microns.

80, 63, 5fi, 40,

80

0, (max O /).

63 56 40

W

II r and m about h and and (0,

From the above table. 3 data c, ie- indicates that obtaining the required clearance for

lateral proshanne 1Nva and the absence of inclusions in the welded joint is achieved when using refractory noropzh dispersion 63, 56, 40 microns, ie at 1H1 and a ratio of 0.25) s1mzk;; 0.56. The results are shown in Tables 1-3, obtained with the following ratios of ingredients in the mixture, May.%: Powder of refractory compounds77

Pivinyl Butyral 13

Solvent (technical ethyl alcohol) K)

The heat resistance of zigzag pastes with a (different) composition of ingredients was determined by the number of thermal cycles that a column of paste withstands 6 mm in diameter and .10 mm long until it decomposes when heated to 600 ° C and cooled to room temperature.

The adhesion strength of the refractory compounds is determined by mechanical tests to compress the specified column from the paste after evaporation of the solvent in it at a constant temperature. The wettability of the protective infusion, which depends on cooTHOijjeHHfl, the content of polyvinyl butyral and solvent in it with a constant amount of refractory refractory with

The welding mode of the samples was s / and blowing: arc current 22 A, pair speed 15. arc length 1 mm.

After welding, it removes the .alitic paste and: the cavity of the plug and pro (I) DI, 1I visual, metallographic and microrein-spectroscopic source of welded IHHOB. The results of the research are given in clause 6.1. 3.

T a b l m It a 3

145

vpuche and absent

122

104

87

72

Individual inclusions

5

0

5

0

5

The distance, determined by the angle |) of the astecapy, is on a flat, flat surface; astin after evaporation of the solvent.

The indicated properties of zippypu paste 6i, i- were determined with a constant dispersion of titanium carbide powder g1mang - 20 μm; powder of chromium oxide with 1 m K. - - 30 microns and Norzha zirconium nitride 56 microns.

The data are given in table. 4-6. On specific formulations of spare 1. Naci.

The electrical characteristics of the proposed protective paste were determined from the processing of the nropess waveforms taken on the daisy-chained oscilloscope graph Hi 15. In studying the electrical characteristics, the following parameters were determined: the probability of arc excitation from thirty ignitions at various ratios of the ingredients in the mixture; arc transient time; the maximum value of the arc burning voltage, as well as the stability of this value. 1 during the welding process. Each of the listed parameters was evaluated using the point system, and their sum gave one of the three indicators given in the table. 7.

When determining the operational characteristics of the proposed protective paste, the following indicators were evaluated; the presence in the solidified paste mass of undissolved polyvinyl butyral; the drying time of the divorced protective paste after filling is shown in table. 7 (investigated

cavity of stupor. Evaluation of indicators in the balance specified in the table. 4-6).

Table A

Properties of a protective paste based on titanium carbide powder with a fineness of 20 microns

74.5

15.5 10

63

no inclusions

40

90

77

15.5 7.5 104

77

15 8 98

Table 6

Properties of a protective paste based on zirconium powder with a dispersion of d ", Kc 56 μm

15,5

10

1A2 inclusions absent

77,

fifteen

115 not included

Continuation of the table. 5

from

2 I

fifty

90

 fifty

thirty

120

45

40

From the above table. 4-7 of the data “The proposed composition of the protective paste follows that the composition of the protective paste possesses-allows. To obtain welded joints with satisfactory properties in the closed end joints in the given adjusted limits of the ratios of ingredient-starts for their lateral sagging, increased. , reads stability of burning of an arch as in pro.

Continuation of the table. 6

Table 7

the process is troubled both in stationary mode and also reduces the laboriousness of loading while loading and removing plugs of protective paste from the cavity of the plug.

Claims (1)

The claims The composition of the protective paste is mainly for fusion welding of closed joints of end joints, for example, ampoules containing a powder from refractory joints, polyvinyl butyral and an alcohol solvent, characterized in that, in order to improve the quality of the welded joint by limiting the lateral sag of the weld due to increased heat resistance and reducing the wettability of the paste, in As refractory compounds, weldable metal compounds of the series oxides, carbides and nitrides with a fineness of 0.25fi s1 "ax; 0.56, where b is the tolerance for lateral sagging of the seam. MKM, .dMaKc is the maximum particle diameter of the powder, microns, and ethanol as the alcohol solvent in the next May component ratio. %: Powder of refractory compounds of a welded material from a series (oxides, carbides and nitrides) 75-85 Polyvinyl butyral 5-15 Alcohol solvent (ethyl alcohol) 8-18