Estimation of the Temperature in the Weld Penetration Channel in Electron Beam Welding

doi:10.4236/jpee.2013.17009

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Journal of Power and Energy Engineering, 2013, 1, 51-53

http://dx.doi.org/10.4236/jpee.2013.17009 Published Online December 2013 (http://www.scirp.org/journal/jpee)

Estimation of the Temp erature in th e We ld Penet ration

Channel in Electron Beam Welding

D. N. Trushnikov, E. S . S alomatova, V. Ya. Belenkiy

Perm National Research Polytechnic University, Perm, Russia.

Email: [email protected]

Received September 2013

ABSTRACT

In this paper, the method of experimental estimation of the temperature in a penetration channel in electron beam weld-

ing is described on the basis of chemical elements concentration in the vapors above welding zone. The temperature of

a vapor-gas phase i n the penetra tion channel is determined when equating calculated and experimental concentrations of

the elements.

Keywords: Electron Beam Welding; The Chemical Composition of the Weld; Austenitny Stainless Steel;

Thermodynamic Calculations; Steam Pressure in the Channel

1. Introduction

Electron beam welding (EBW) plays a special role among

welding methods because of high power concentration in

a welding electron beam and the ability of its deep pene-

tration into the metal. These cause wide application of

EBW in the manufacture of parts for critical products

from various steels and alloys.

At the moment, there is a considerable success in the

numerical simulation of electron beam and laser welding

by static electron beam [2-4], but the complete dynamic

models describing the processes in penetration channel at

EBW with periodical influence on the electron beam are

absent till present. The complicity and speed of these

processes make it difficult to carry out computer simula-

tion and numerical experiments even at the modern level,

there is the necessity to search the ways for experimental

investigations. Besides, when simulating laser welding,

which is similar to the electron beam processes, the tem-

perature in the penetration channel is usually taken to be

equal to the boiling temperature at the atmospheric pres-

sure, but electron beam welding is carried out under va-

cuum, and this approach for the simulation of electron

beam welding is not suitable for getting the required ac-

curacy of the results.

Experimental methods for measuring the temperature

in the penetration channel also face with difficulties. The

applying of pyrometrical methods is complicated by the

significant value of secondary light emission from a weld-

ing zone.

2. Research Methods

In this paper the method of experimental estimation of

the temperature in a penetration channel in electron beam

welding is described on the basis of chemical elements

concentration in the vapors above welding zone.

The background of the experimental technique was the

determination of the temperature in a penetration channel

in electron beam welding on the basis of chemical com-

position of the vapors formed above welding zone. For

the experimental estimation of the vapor composition

with the use of electron beam apparatus with the energy

aggregate ELA-6VCh, produced by “SELMI” (Ukrane),

oscillating electron beam passed along the sample made

of austenitic steel 321. The plate made from aluminium

alloy 512,0 (AMц-3) has been settled around the zone of

electron beam influence on the sample (at a distance of

15 mm). The material of the plate was chosen in terms of

minimal coincidence of the alloy chemical composition

with chemical composition of the steel 321. Electron

beam power in the experiments was 3.6 kW (accelerating

voltage was 60 kV), welding speed was 3.2 mm/s, oscil-

lation frequency and amplitude of the beam we re 650 Hz

and 1 mm, respectively.

The experiment pattern is shown in Figure 1. During

the influence of oscillating electron beam on the sample,

which was made from the steel 321, in dagger penetra-

tion mode, evaporation of the elements occurred with

their following d eposition on the plate made from alum i-

nium alloy.

Later roentgen fluorescent analysis of the obtained

Estimation of the Temperature in the Weld Penetration Channel in Electron Beam Welding

Figure 1. The experiment pattern on the analysis of the

elements evaporation from steel 321 during electron beam

action: 1—electron gun; 2—electron beam; 3—melt metal;

4—base material; 5—aluminium plate; 6—metal vapors

from the zone of electron beam action.

coating, aluminium plate and the sample, which was in-

fluenced by electron beam, has been taken. Data obtained

are represented in Tables 1-3.

The elements from the plate were subtracted from the

chemical composition of the coating to determine the

amount of alloying elements evaporated from the steel

321 during oscillating electron beam action. Results of

the calculation are represented in Table 4.

Thus during electron beam influence on the sample,

made from steel 321, an intensive evaporation of iron,

chrome and manganese takes place.

Obtained experimental data were compared with the

results of thermodynamic calculations to estimate the tem-

perature in the penetration channel, which was formed in

the metal by electron beam.

At thermodynamic calculations the content of each

chemical element Сi in vapor-gas phase of penetration

channel was determined on the basis of the chemical

composition of metal sample (Table 2) according to the

equation:

itotal

(1)

where total vapor pressure Ptotal in the channel is the sum

of partial pressures of the elements from the alloy (Рi).

It can be seen that vapor pressure in the channel main-

ly depends on the pressures of three elements which are

iron, chrome and manganese.

Then the results of thermodynamic calculation, made

with the use of the Equation (1), were compared with the

results of chemical analysis of the deposited coating to

estimate the temperature of a vapor-gas phase in penetra-

tion channel. Calculation results for the chemical comp o-

sition of vapor-gas phase within the electron beam weld-

ing zone are represented in Figure 2 (only for iron,

chrome and manganese, because the content of the other

elements can be neglected), and the concentrations of

chemical elements obtained with the use of roentgen flu-

Table 1. Chemical composition of aluminium plate (alloy

512,0 (AМц-3)).

Chemical elements Al Mn Fe S Crо Zn Ti Ni

Element content, % 98.88

0.40 0.28 0.18 0.12 0.04 0.04 0.03

Table 2. Chemical composition of the sample (steel 321).

Chemical elements Mn Si Cr Ti Ni C Fe

Element content, % 1.27 0.50 18.99 0.59 10.14 0.09 68.42

Table 3. Chemical composition of the coating.

Chemical elements Fe Cr Mn Al Ni

Element content, % 33.36 24.94 34.81 2.85 1.891

Table 4. Amount of alloying elements evaporated from steel

321.

Chemical elements Fe Cr Mn Ni

Element content, % 33.08 24.82 34.41 1.891

Figure 2. Correlation between iron, manganese and chrome

concentrations in the channel for the steel 321 and the tem-

perature.

orescent analysis at experimental research (horizontal

lines) are also shown in the figure.

The temperature of a vapor-gas phase in the penetra-

tion channel is determined when equating calculated and

experimental concentrations of the elements, and it was

2590 K (for Fe), 2610 K (for Cr) and 2730 K (for Mn).

As it is clear from the data obtained the difference be-

tween the temperatures is insignificant (about 5 %) and it

can be caused by indirect character of the applied method

which accuracy is still difficult to estimate.

Thus the temperature determined in the experiment on

the basis of the analysis of components evaporation from

steel 321 was 2600 K. It is necessary to note that the

temperature in the penetration channel is changeable in

depth and undergoes fluctuations over time. When elec-

tron beam oscillating the zone of maximal energy release

reciprocates from the surface to the depth of the channel

and reverses [5], the temperature of any single element of

the penetration channel becomes a periodic function. The

time -average temperature rises with the depth increasing

Temperature, К

Concentration of chemical elemen ts in the vapor-

gas channel , %

exper.

calc.

exper.

calc.

Estimation of the Temperature in the Weld Penetration Channel in Electron Beam Welding

in the penetration channel. At the same time significant

part of the vapors condenses on the walls during the

movement from the depth of the penetration channel [6].

The statement concerned is confirmed with the analysis

of the chemical composition of the weld seam along its

depth, which shows that noticeable depletion of the metal

with alloying elements takes p lace only in higher ar eas of

metal. According to this, the described method allows to

determine only a certain temperature of a higher part of

penetration channel which corresponds to a time-average

vapor composition. Obtained data are in a satisfactory

agreement with the results of the work [4].

The research was carryed out under the support of the

grants RFBR-Ural No. 11-08-96016, RFBR No. 13-08-

00397A and the financial support of the Ministry of edu-

cation of t he Perm region.

3. Conclusions

The method of experimental estimation of the tempera-

ture in the range of interaction of the beam and walls of

penetration channel has been suggested. The method is

based on vapor concentration measurement above weld-

ing zone with the use of chemical analysis of a film de-

posited on a substrate located near welding zone. The

temperature of higher areas of the penetration channel,

corresponding the time-average vapor composition at the

welding with depth of 7 mm of the steel 321, was about

2600 K. Experimentally determined temperature in the

channel was in a good agreement with existing estima-

tion.

The obtained results can be used further in the calcula-

tion of intensity of evaporation processes in the channel

it electron beam welding; this will permit to determine

the corresponding costs of thermal energy and to take

into account this factor at a numerical solution of the

connected thermal and hydrodynamic problem.

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http://dx.doi.org/10.1063/1.1702787