EIR-BericM Nr. 353

Eidg. Institut fur Reaktorforschung Wurenlingen

Schweiz

The compatibility of steel and aluminium with calcium chloride/ammonia, magnesium chloride/methylamine

and magnesium chloride/methylamine/decane

H.K Kohl

ifr Wurenlingen, Mai 1978

EIR - BERICHT NR.

Eidg. Institut fiir Reaktorforschung WUrenlingen, Schweiz

The compatibility of steel and aluminium with

calcium chloride/ammonia, magnesium chloride/methyl-

amine and magnesium chloride/methylamine/decane

H.K. Kohl

EIR, WUrenlingen, Mai 1978

1 -

Contents

1. Introduction

2. Materials

2.1. Metals

2.1.1. Shape of the samples

2.1.2. Surface and weight

2.2. Chemical substances

2.2.1. Calcium chloride (CaCl2)

2.2.2. Magnesium chloride (MgCl2)

2.2 3. Ammonia (NH.)

2.2.4. Mciiomethylamine (CH^NH-)

2.2.5. Decane (CH3(CH2> ,/H^)

3. Compatibility treatments

3.1. Autoclave experiments

3.2. Pressure and temperature

3.2.1. CaCl2/NH3

3.2.2. MgCl2/CH3NH2

3.2.3. MgCl2/CH3NH2/CH3(CH2)8CH3

3.3. Duration of the experiments and review of the treatments

4. Experimental results

4.1. Weight changes

4.2. Surface

4.3. Fatigue strengths

4.4. Metallographical investigations

5. Discussion of the experimental results

6. Summary

- 2 -

1. Introduction

The use of pairs of substances such as calcium chloride /ammonia

or magnesium chloride /methylamine for distant heating or heat

storage requires compatibility between these substances and

the structural materials of the reactor vessels, transport-

containers, and/or heat exchangers. Readily weldable mild

steel or aluminium are considered likely candidates for the

structural materials for transport containers or heat ex­

changers .

The corrosion behaviour of steel and aluminium against one

of the components of a pair of reactants, e.g. calcium chloride

can be found in tables, e.g. in the "Dechema-Werkstofftabellen"

or in the "Aluminium-Taschenbuch". However, information re­

garding the effect of a pair of reactants is not so readily

available. Therefore compatibility tests must be performed

with the pairs of substances and metals under the conditions

of heat transport, heat storage or heat exchange.

In these compatibility investigations the metal samples

have been held in contact with the chemical substances under

different conditions (temperature, pressure, time) and after

the compatibility treatments, the samples were tested.

When there is no detectable change in the properties of the

samples after the compatibility treatments (in comparison with

the as received status) the compatibility is deemed good.

Weight changes, surface investigations, fatique strength

tests and metallographical investigations were perforated for

determining this "compacibility".

- 3 -

2. Materials

2.1. Metals

Readily weldable ferritic carbon steel and aluminium were

chosen as structural materials. Mild steel St37, the man­

ganese alloyed fine grained steel StE36 and the non- precipi­

tation hardening aluminium alloys A199.5 end Al-Mg3, often

used for the construction of chemical apparatus, were tested.

Table I shows the chemical composition and the mechanical

properties of the test materials in their initial states.

The rod shaped samples were taken out of plate material,

12 and 15 mm thick, respectively transverse to the rolling

direction of the plates.

For the chemical composition, the standard compositions,

guarantees of delivery, analysis from the supplier, and

analysis, obtained by optical spectral analysis and the

atomic absorption method, are given.

2.1.1. Shape of the samples

The rotating fatigue strength sample after DIN 50 113 was

used for the compatibility treatnents and the following tests.

This sample is shown in Fig. 1.

Fig. 1 Rotating fatigue sample, W * 0.03 cm (test length

"a" is polished in longitudinal direction)

- 4 -

2.1.2. Surface and weight

The steel and aluminium samples had the same shape and there-2

fore the same surface area of 23.8 ± 0.5 cm .

The weight of the samples was for metal A: 35.789 ± 0.O47 g,

B: 35.904 ± 0.054 g, C: 12.516 ± 0.006 g, D: 12.369 i 0.005 g.

The weight was determined with an accuracy of ± rrr mg.

2.2. Chemical substances

2 . 2 . 1 . Calcium chloride (CaClQ

The compound CaCl2 • 8 NH. was prepared from molten and

granulated calciumchloride p.a. (grain size = 0 . 5 - 2 mm),

supplied by MERCK. The minimum degree of purity was 93 t.

Free alkali, Ca(0H),, was 0.5 t max. and the water content

was 1.5 %.

2 . 2 . 2 . Magnesium chloride (MgCl,,)

Magnesium chloride , used e.g. for preparation of the compound

MgCl2 • 5CH3 NH2, was delivered from the french company

COMINTEX S.A.

The average analysis of this product is given in Table II.

2.2.3. Ammonia (NHj)

The ammonia used contained about 1 % free nitrogen and 0.1 %

water. It was dried with NaOH-pellets and therefore the water

content was < 0.1 %. The water in the ammonia was bonded

on to the calcium chloride.

- 5 -

2.2.4. Mono—thy lamine (CH-HH-)

The monomethylamine used was delivered froai the company

FLUKA. The water free product had a purity of 97 t and

contained about 3 t (CH3)_ Nil + (CH-jKN, and traces of HR3.

2*2*5* Decade (CH3 (CH^pCH,)

Decane (alkane C.-) was also obtained from the company

FLUKA. This product had a purity of i 95 1 (GC) and contained

cycloparaffii

MG = 142.22.

cycloparaffine. The boiling point was 174 C, density = 0.73,

3. Compatibility treatments

3.1. Autoclave experiments

The compatibility treatments were carried out in stainless

steel autoclaves. The experimental arrangement is shown

in Fig. 2.

The volume of the autoclave was about 1.5 litre. The samples

were fixed into bored holes of a teflon disc, located

in a beaker, which contained about 0.3 kg CaCl- • 8 NH-,

MgCl- • 5CH.NH2, or MgCl2 • 5 CH.NH, suspended in decane,

respectively.

The charging of the autoclaves with the complex compounds

was performed in a box, fitted with a pure nitrogen lock

to ensure that air and water vapour are excluded. The

autoclaves were closed in this environment and then charged

through the valve with ammonia or methylamine, respectively.

- 6 -

Ammonia was passed over NaOH-pelletsr as already mentioned,

to remove traces of water.

To condense ammonia and methylamine in the autoclaves,

cooling was provided by a freezing mixture on the outside.

The autoclave for the room temperature experiment contained

about 3/4 kg of liguid ammonia. The autoclaves for the

70° - and 130° - experiment were heated slowly and when the

nominal temperature was reached, the pressure was adjusted

to 15 bar, by opening the valve and blowing off the excessive

ammonia.

During heating up, the autoclave (for the 130° - experiment)

passed over the temperature/pressure equilibrium for CaCl- *

8 NH3/CaCl2 • 4 NH3 and that one for CaCl2'4 NH3/CaCl2 • 2 NH3

yielding an output of ammonia and increasing pressure. For

this reason the pressure must be lowered repeatedly.

Similar relations were present in the system MgCl./CH^NH..

3.2. Pressure and temperature

3.2.1. CaCU/NHj

Fig. 3 shows the experimental conditions, pressure and

temperature, at which the experiments with CaCl2/NH3 were per­

formed. As the figure shows, the pressure in the room tempera­

ture experiment is higher,than the equilibrium pressure

NH3 - liquid/NH3 - vapour. This means, that the liguid ammonia

is compressed.

The autoclave was filled entirely with liquid ammonia due

to cooling of the apparatus. During heating up to room

temperature the pressure exceeded the equilibrium pressure.

- 7 -

3.2.2. MgCU/CHjNH^

In Fig 4 the experimental conditions, pressure and temperature,

are shown, at which the experiments with NgCl^/CB-NH. were

performed. The data 6a) to 8a) relate to the first charge and

the 6b) to 8b) to the second one. As this figure shows, the

pressure in the room temperature experiment was again higher

than the equilibrium pressure.

The pressures after the first and second charging differed

somewhat; «i change in the composition of the complex compound

resulted from this.

3.2.3. MgCl2/CH3NH=/CH3(CH2> 8CH3

Experiments were performed, in which MgCl • 5CH-NH- was sus­

pended in decane. The metal samples were surrounded with

decane, in which fine grained MgCl_ • 5CH,NH2 was suspended.

Depending on pressure and temperature, a certain amount of

methylamine is disolved in decane, as Fig 5 shows.

In the room temperature experiment the pressure dropped during

the experiment from about 3 to 1.5 bar and at 78°C from 3 to

0.5 bar.

In the experiment at 172°C at the beginning of the experiment,

the pressure changed, due to heating and opening of the valve.

At constant temperature the pressure increased from 15 to 18

bar.

- • -

3.3. Duration of the experiments and review 01 »he treatments.

The nominal duration of the experiments was 1O0O hours.

Table III gives a review of the various treatments. In the last

column the experimental times are given.

Depending on pressure and temperature, ammonia or methylamine

is liquid or vapour and the complex compounds have a certain

composition.

The state of aggregation and the composition of the chemical

compounds, with which the metal samples have been in contact

during the experiments, are also given.

To distinguish between the chemical and thermal influence on

the fatigue strengths, samples were heat treated in vacuum

over about 1000 hours at similar temperatures, at which the

compatibility experiments with calcium chloride and ammonia

were performed.

4. Experimental results

4.1. Weight changes

In the experiments with calciumchloride/anmonia after about

1000 hours, both, weight losses and weight gains of the samples

were observed. The weight changes after the various treatments 2

are shown in Table IV. The weight changes are given in mg/m /h.

These figures correspond for steel to those for the loss in

wall thickness in um/a, if the wall nudation is uniform over

the whole surface. For aluminium the wall loss is about three

times greater.

9 -

At room tiimature steel St37 exhibited weight losses with

CaClj/iMj. Two samples of four from the fine grained steel

StE36 showed a weight loss and two a weight gain.

In the 70°C experiment a weight loss for steel 37 and pure

Al was observed. With steel StE36 and the aluminium alloy

Al-Mg3, a weight gain was found.

The 130°C experiment showed for St37, a weight loss and for

the other metals-, a weight gain.

Generally the treatments with CaCl_/HH3 caused only snail

weight changes, corresponding to negligible losses in wall

thickness.

In the experiments with magnesium chloride and methylamine

at all temperatures only weight losses were found, depending

on experimental conditions and metals. After an experimental

time of about 1000 hours, the samples were weighed and then

again compatibility treated under nearly the same conditions.

In Table IV, a), refers to the experimental conditions and

weight changes after the first 1000 hours and, b), after the

second ones.

In the room temperature experiment after the first 1000 h

the differences in the weight losses of the different metals

were within the statistical spread, as the analysis of variance

shows.

In the 80°C experiment the weight losses were in the same

order of magnitude, as in the room temperature experiment.

The calculated wall losses were less or equal to 1 pm/a.

At 180°C after the first 1000 hours the weight losses were

about one order of magnitude higher.

10 -

After the second 1O00 hours at room temperature and tO°C less

weight losses were determined, compared with such after the

first 1000 hours. At ltO°C the weight losses after the second

1000 hours were increased, particularly on the aluminium alloy

samples by a further order of magnitude.

In the exper jsents with decane plus suspended HgClj • 5CH-1SJ.,

at all temperatures, only weight losses were observed.

In the room temperature experiment, the performances of the

aluminium alloys were better than that of steel. But even for

steei., the room temperature weight losses were not serious.

They corresponded to a wall loss of 1 to 2 um/a.

At 78°C steel and aluminium behaved very well. All metals showed

only small weight losses.

At 172°C the weight losses for the aluminium alloys were by a

factor of 1000 higher. Steel was more severeley attacked, too.

These experiments confirmed the results of the experiment with

magnesium chloride and methylamina, performed at 180°C, which

also showed much stronger attack, particularly on aluminium.

4.2. Surface

After the experiments with CaCl2/im3 the samples had still the

polished appearance. On the samples of pure aluminium Al 99.5,

some small local pits were found.

After the treatment with HgCl./CH.NH, the samples were more

severely attacked. Pig 6 shows steel samples aft*r a treat­

ment of about 2000 hours. After the experiments at room tempera-

- 11 -

ture and 80°C, the steel samples showed a yellow brown colour

(sample on the left and in the middle). The sample on the right,

after the 180°C experiment, showed already a roughaned sur­

face.

Depending on the temperature, the aluminium samples differed

strongly in th ir appearance after the experiments, (in con­

trast to the .teel samples), Fig 7. At room temperature and

80 C (en the left and in the middle) the samples had the same

appearence after the experiments, as before, but showed local

attack. At 180°C the whele surface of the sample is covered

with a reaction product (sample on the r.tght) .

A similar appearance was exhibited by the samples after the

treatments in suspension. The different attack at different

temperatures, expressed in weight losses, can be observer)

directly from their appearence. In Fig 8 samples from ste3l

StE36 are shown, which were treated at different temperatures:

at room temperature (on the left), 78°C (in the middle) and

172 C (on the right). The sample treated at 78°C showed a

polished surface similar to that at the start of the test.

The samples treated at room temperature showed a yellow

colour, and after the treatment of 172°C, their surfaces

were rougnfc*:sd.

No change of the polished surface occured JH the aluminium

samples after the treatment at room temperature and 78°C,

Fig 9. After the treatment at 172°C the samples were heavily

attacked, particularly at the lower part, where they were in

contact with in decance suspended MgCl2»5CH3NH2, which was

deposited during the experiment.

- 12 -

4.3. Fatigue strengths

After the compatibility treatment, the samples were fatigue

tested in air at room temperature (rotating-beam machine,

SCHENCK PUNZ). The frequency of the stress cycles was 100 Hz.

The experimental results are compiled in Table V to VIII.

The tables contain the logarithms of the number of cycles

to fracture, depending on treatment and stress amplitude.

In the range, in which the number of cycles is dependent on

the stress amplitudes, regression analyses for the four ma­

terials were performed.

By calculating the regression of the logarithms of the number

of cycles in dependence of the stress amplitudes, the loga­

rithms of the number of cycles must be plotted on the y-axis

and the stress amplitude, ± a , on the x-axis. Y represents s

the random variable and, X, the chosen stress amplitude, the

independent variable. This gives an unusual picture, because

it is general practice, to plot the stress on the y- and the

number of cycles on the x-axis.

In Fig 10 to 12 the regression lines of the logarithms of the

number of cycles, depending on the stress amplitudes, in the

above mentioned manner, are plotted.

In Fig 10 the results after treatment with calcium chlorid/

ammonia and in vacuum are added to those, obtained for the

initial status; in Fig. 11, those after treatment with ma­

gnesium chlorid/methylamine, and in Fig 12 the results after

treatment with magnesium chlorid/methylamine/decane.

In Table IX, the equations f">r the regression lines (in the

range, where the number of cycles are dependent on stress

- 13 -

amplitude) are represented. This range, the fatigue limit,

and the range for fatigue limit, for the four materials are

also given.

If the point* for the as received status, which determine the

regression line, are regarded as a sample of a normal dis­

tributed population, a confidence interval for the mean

value of the population can be given, which for the confi­

dence coefficient, y = 95 %, is also plotted.

These plots show, that the number of cycles of the compatibi­

lity treated and tested samples nearly all lie within the con­

fidence intervals.

The aluminium samples treated at 180 C with magnesium chloride/

methylami^e and magnesium chloride/methylamine/decane were

so much attacked, that fatigue tests with these samples would

have been of no real value.

4.4 Metallographlcal investigation

The treatment of steel and aluminium with magnesium chloride/

methylamine and with magnesium chloride/methylamine/decane

at 180°C (172°C), has shown severe attack particularly on

aluminium. On the steel samples the surface was roughened and

the aluminium samples showed a reaction layer and local deep

attack. These samples were not fatigue tested, because the

original cross section, on which the stress calculation is

based, was significantly reduced. The steel samples were

fatigue tested, although the polished surface was lost during

the compatibility treatment. As Fig 11 and 12 show, the points

for the number of cycles lie within the confidence interval. A

substantial change of the fatigue strength was therefore not

indicated.

14 -

The samples treated at 180°C (172°C) were metallographically

investigated, to establish the amount of attack.

Figs 13 and 14 show longitudinal sections of steel samples in

5.5 times magnification and photo micrographs in 100 times

magnification. These samples had been in contact with magnesium

chloride/methylamine or with m? nesium chloride/methylamine/

decane at 180°C (172°C). With 5.5 times magnification from

the picture no attack on the surface of the samples was

detectable, however, some attack was present, as the photo

micrographs show. This fairly constant attack did not sig­

nificantly influence the fatigue strength.

The reason for the greater spread of the number of cycles

with steel StE36, is presumable the banding structure. Figs

15 and 16 show longitudinal sections and photo micrographs of

the aluminium alloys Al 99.5 and Al-^3, after the treatments

at 180°C (172 C) with magnesium chloride/methylamine and

magnesium chloride/methylamine/decane. As the photo micro­

graphs show, the attack is not constant. The local attack goes

deeper, as would be calculated from the weight losses, presuming

a constant denudation.

5. Discussion of experimental results

The determination of the weight changes of the samples after

the treatments, the examination of the surfaces, the fatigue

test in the initial status and after the treatments, and the

metallographical investigations gave a good picture of the

compatibility of the investigated materials with the pairs

of chemical substances.

- 15 -

The best over all compatibility was found with the substances

CaCl_/NH3. In the temperature range from room temperature

to 130°C only negligible weight changes were established. The

compatibility of MgCl2/CH3NH2 with the tested materials

depended stronghly on temperature. At room temperature and

70 to 80 C the compatibility is deemed good, whereas at

170° to 180°C the compatibility with steel is reduced,

and with aluminium, no longer existent. The same results

were obained in the experiments with suspension, in which

MgCl. • 5CH.NH2 was suspended in decane.

The appearence of the samples after the treatments gives a

good impression about compatibility. The fatigue tests

support the results, obtained from the weight changes.

A noteworthy result is that the roughened surfaces of the

steel samples after the treatments at 180 C (IT 2 C) did not

significantly influence the fatigue strength.

The local attrcks are obviously rounded and caused no pre­

mature fracture initiation due to stress raisers.

It should be noted, that the fatigue tests are not performed

in the attacking environment, but in air. The experimental

conditions can only be adjusted within autoclaves. Fatigue

tests under such conditions are therefore hardly possible

At the planning of the experiments the idea was followed,

that a chemical attack on the surface would influence

the fatigue strength, and that this can be determined with

fatigue tests after the compatibility treatments. The

fatigue tests after the compatibility treatments showed,

that on the steel samples no appreciable material damage,

neither internal nor external has occured.

- 16 -

The strong attack on the aluminium samples at 180°C (172CC)

is possibly caused from the decomposition of methylamine on

the aluminium surfaces at this temperature.

The comparatively much stroncer attack on aluminium than on

steel at 180°C (172°C) is possibly based on the lower re-

crystallization temperature of aluminium compared with steel.

Thermally activated processes are therefore faster in alu­

minium than in steel.

The initial status of the aluminium samples was cold rolled

wheras the steel samples were in hot rolled or annealed con­

ditions. The corrosion resistance of a hot rolled material is

better, compared with cold rolled.

The metallographical investigations showed, that the material

denudation on the steel samples was constant, whereas on

the aluminium samples local often deep attack took place.

6. Summary

The compatibility of the structural materials St37, StE36,

A199.5 and Al-Mg3 with the chemical substances CaCl2/NH3,

MgCl2/CH3NH2 and MgCl2/CH3NH2/CH3(CH2)gCH3 was investigated.

The compatibility treatments were performed in autocides at

room temperature, 70° - 80°C, 130°C and 170° - 180°C, res­

pectively. The nominal duration of the experiments was

1000 hours.

Rod shaped fatigue samples with polished surfaces served as

test material. These samples were fatigue tested after the

compatibility treatments, if not, the weight changes already

showed, that no compatibility was existent.

- 17 -

All tested structural materials were compatibel with CaCl./

NH. under the given experimental conditions.

With the chemical substances MgCl2/CH3NH. a good compati­

bility at room temperature and 80 C was established (wall

losses in the order of 1 ym/a). At 180°C attack on steel

and particularly aluminium was much heavier. The attack was

accelerated with time, after the second 1000 hours, whereas

at room temperature and 80°C the attack diminished with

time. At 180 C aluminium was not compatible with MgCl~/

CH~NH~.

The experiments in the system MgCl2/CH3NH2/CH3(CH2)8CH3,

in which MgCl_ • 5CH-NH- was suspended in decane, confirmed

the results of the experiments with magnesium chloride/

methylamine. Decane had no additional influence on com­

patibility. At room temperature and 78°C again good compatibi­

lity with the metallic samples was established but at 172°C

aluminium was incompatible.

The fatigue test confirmed the compatibility of steel and

aluminium with calcium chloride/ammonia at room temperature,

70° and 130°C, with magnesium chloride/methylamine at

room temperature and 80°C and with magnesium chloride/

methylamine/decane at room temperature and 80 C.

At 180°C considerable attack on steel samples was found after

a treatment with magnesium chloride/methylamine and in

magnesium chloride/methylamine/decane. This attack, however

did not influence the fatigue strength of the steel samples,

therefore steel, under the above menioned conditions is also

regarded as compatible.

Table I Initial status, chemical analyses, and mechanical properties of the tested aateriala

Parameter

Producer

I n i t i a l s t a t u s

Chemical composition

weight - %

1

cal

properties

Hechani

I 2 • *>

I

I

Elements

Fa

Al

C

N

P

S

*» Si

Mn

Cu

2n

Ti

m

T e n s i l e

strength

N/mm2

Elong­ation at fracture %

Impact

energy

J

B r i n e l l

hardness

HB

N/mm2 In

Fatigue strength under bending stress N/tarn2

Fatigue stangth under pulsstin

N/mm2

A

S t r u c t u r a l s t e e l

S t 37

N. Mr. 1 .0112

C i l l l n g e r Htlttenverk

hot r o l l e d

not annealed

P l a t e thickness-12mn>

Res idual

£ 0 . 1 8

£ 0 .007

i. O.05O

S 0 . 0 5 0

0 .20-0 .50

2 235

360-440

i 25

0 . 1 2

£ 0 . 0 1

£ 0 . 0 5

£ 0 . 2

0 . 8 5

Check-a n a l y s e s

369+14

431+3

2 8 . 9 + 1 . 0

i 27 (a t -20°C)

(ISO-V-sample)

i

B

Fine gra ined s t e e l

S t E 36

N. Nr. 1 .03SI

Thyssen Henr ichshut te AG

f u l l y k i l l e d s t e e l

normal ized

P l a t e t h i c k n e s s - 15 mm

Res idual

2 0 .015

£ 0 . 2 0

£ 0 . 0 4 0

£ 0 . 0 4 0

0.1O-O.50

0 . 9 0 - 1 . 6 0

0 . 1 7 / 0 . 1 6

0.O12/iO.OO8

0 . 0 1 5 / £ 0 . 0 5

0 . 3 1 / 1 0 . 2

1 . 3 6 / 1 . 4 1

'The f i n e gra ined s t r u c ­ture i s e s t a < 0 .015 % Al or due t o 2 combinat ions e l e m e n t s .

> 355

490-620

* 22

2 48 at -20°C

(EKM-sample)

b l i s h e d due t o or > O 02 % Nfa

0 . 0 5 % V o r of t h e s e

ladle analyses/ Check analyses

379 2)

390 3 )

378+19

562 2)

585 3>

504+2

27 2)

26 3 ' 2 5 . 1 + 1 . 1

592> a t

6 4 3 ) -20°C

(DVH-sample)

21 ' B a s e / c r o s s

T o p / c r o s s

C

Pure aluminium

Al 9 9 . 5 %

1500

D

Peraluman-300

Al-Hg 3

5300

Schw.Aluminium ACSchw.Aluminium AG

c o l d r o l l e d

Plate thickness«12aa

< 0 . 4 0 Residual

< 0 . 0 5

£ 0 . 3 0

£ 0 . 0 5

£ 0 . 0 5

£ 0 .07

£ 0 . 0 3

( 1 . 0 )

(0 .0075)

( 0 . 5 )

(£0 .005)

(£0 .006)

•£0 .04)

(£0 .006)

Check-a n a l y s e s

106+6

113+3

1 0 . 1 + 0 . 2

(at room

i. 74 temper a tur)

(VSM-sample)

30

40

50

c o l d r o l l e d

Plate thickneas-12nm

£ 0 . 3 Residual

2 . 6 - 3 . 1

£ 0 . 4

0 . 1 - 0 . 5

£ 0 . 0 5

£ 0 . 1

( 0 . 6 )

2 . 8 5

( 0 . 3 )

( 0 . 3 5 )

(0 .06 )

( £0 .03 )

( 0 . 0 4 6 )

Check-a n a l y s e s

151+1

214+1

1 4 . 9 + 0 . 6

90

100

150

- 19 -

Tabelle II Average impurity levels of magnesium chloride

supplied by CONINTEX S.A.

MgO

CaCl2:

Al

B

C !

Cd

Cr

Ca

Cu

Fe

Nn

Ni

Si

Sn

Ti

Na

Zn

Zr

Pb

<

<

<

<

<

; <

• <

: <

t <

: <

; <

» <

• <

• <

; <

» <

• <

: <

0.1

0.5

100

5

%

%

ppm

ppm

undeterminable

5

50

50

10

50

10

10

500

10

10

50

100

500

10

ppm

ppm

ppm

ppm

PP"»

ppm

ppm

ppm

ppm

ppm

ppm

ppm

ppm

ppm

insolable in water : < 0.5 t

radioactivity: none

20

Table III Review of the treatments

No. of the type of treatment

0

1

2

3

4

5

6

7

8

9

10

11

Condi t ions of t h e t r e a t m e n t s

Medium

un­

t r e a t e d

Calcium chloride-

Ammonia

>

Magnesium chloride-

Methylamine

Magnesium chloride-

Methylamine-

Decane

Temp., °C Pressure, bar Time,h

t h e m a t e r i a l i s i n t h e i n i t i a l s t a t u s (see

Table I ) , t h e sample sur face i s p o l i s h e d

NH3, l i q u i d

CaCl2-8 NH3, s o l i d

NH_-vapour

CaCl2*8 NH3, s o l i d

NH3-vapour

CaCl2«2 NH3, s o l i d

CH3NH2, l i g u i d

MgCl2*5 CH3NH2,solic

CH3NH2-vapour

MgCl2 '5 CH3NH2,solic

CH3NH2-vapour

MgCl2*3 CH3NH2,solic

CH3(CH2)8CH3,liguid

CH3NH2-vapour

MgCl2 '5 CH-NH^solic

CH3(CH2)8CH3, liguid

CH3NH2~vapour

MgCl2*5 CH3NH2,aoli(i

CH3(CH2)8CH3, liguid

CH3NH2-vapour

MgCl2 '3 CH3NH2,»olid

12,6+1,8

70,4+2,7

129,5+3,4

: 70

: 130

»)21, 2+1,0

b)18,9+l,3

»)79,0+O,3

b)79,0+0,3

»)179,1+1,4

t>) 179,8+1,1

18,0+1,6

78,4+1,4

172,2+10,3

9,4+0,4

14,2+0,4

15,4+0,7

: i o " 7

: i o " 7

9,1+0,1

5,8+0,8

4 ,2+0,3

2 ,9+0,9

5,4+0,6

9,4+1,2

1,8+0,4

0 ,6+0 ,2

14,8+4,5

1032

1098

1104

: IOOO

Z 1000

1240

1168

940

1152

1000

1152

1200

1152

1048

Table IV Results for the weight changes during the compatibility treatments in mg/m2/h (mean value of four or five samples)

• •

P a r a m e t e r

T r e a t m e n t - N o .

D u r a t i o n o f t h e

e x p e r i m e n t s , i

T e m p e r a t u r e ^ * ^ ^

^ ^ ^ ^ P r e s s u r e , b a r

Met

als

M i l d s t e e l

S t 37

F i n e g r a i n e d s t e e l S t E 36

A l - a l l o y

A l - 9 9 . 5

A l - a l l o y

A l - M g 3

P a i r s o f S u b s t a n c e s

C a l c i u m c h l o r i d e / A m m o n i a

1

1 0 3 2

1 3 / 9

-0 .12+0 .06

±0.00*0.19

-0.08+0.CX

-0.07+0.CV

2

1 0 9 8

7 0 / 1 4

-0 .11+0 .06

+ 0 . 0 8 ± 0 . 1 1

-0 .03±0 .04

-K>.05±0.03

3

1 1 0 4

1 3 0 / 1 5

-2 .28±4 .06

+0.07+0.21

40 .19+0 .10

4O.14+0.05

Magnesium chloride/MsthylamlJie

6

a) 1 2 4 0

3) 1 1 6 8

a) 2 2 / 9

3) 1 9 / 6

-0 .53+0 .11

-0 .22+0 .13

-0 .41±0 .28

-O.47±0.18

-0.3O+O.19

-0 .05+0 .05

-0 .40+0 .22

-0 .05±0 .07

7

9 4 0

1 1 5 2

7 9 / 4

7 9 / 3

-0 .68+0 .23

-0 .26+0 .22

-1 .04+0 .06

-0 .19+0 .16

-O.33+0.31

0 . 0 7 + 0 . 0 5

-0 .15±0 .03

-0 .06+0 .01

8

lOOO

1 1 5 2

1 7 9 / 5

1 8 0 / 9

-8 .29± 1 .9]

-9 .59+ 1.9C

-9 .96± 1.7:

-14.86+ 3.9(

-11.60+ 6.7;

-92.27+10.42

-3 .85± 3 .7]

-82.20+17.18

Magnesium chloride/MBthylaalJie/

Decane

9

1 2 0 0

1 8 / 2

-1 .03±0 .05

- 1 . 9 2 ± 0 . 1 8

-0 .14±0 .04

- 0 . 0 1 ± 0 . 0 1

1 0

1 1 5 2

7 8 / 1

-O.07+0.05

- 0 . 0 6 ±0.04

-O.06±0.02

- 0 . 0 8 ±0.03

1 1

1 0 4 8

1 7 2 / 1 5

- 2 . 8 9 ± 0 . 1 9

- 3 . 0 8 ± 0 . U

- 1 6 6 . 0 0 ±

2 5 . 0 0

- 1 4 1 . 5 1 1

3 5 . 7 9

+: weight gain, -: weight loss, 1 mg/m /h a 1.1 vim/year for steel, 1 mg/m*/h * 3.3 urn/year for aluminium

Table V Logarithms of the number of cycles of steel St37 at various stress amplitudes

in the rotating beam test

Samples in the initial status and after various treatments

Type of

treatment

O

1

2

3

4

5

6

7

8

9

10

11

2 Stress amplitude, + oa in N/mm

245

8,03623IXI

8,04258Ii:t

260

6,19117

270

5,83759

6,03981

6,36884

6,64895

7,4743s111

5,94547

284

5,30535

5,66464

5,18752

5,55751

5,83696

5,35793

294

5,05690

5,36173

5,33046

5,40483

5,32838

5,20412

5,33445

5,40993

5,01284

5,32428

5,36549

1,81291

343

4,32222IX

392

3,60206X

441

3,30l03X

Sample red annealing Sample dark blue Sample not fractured Sample bent Sample with scratches and impact spots

Table VI Logarithms of the number of cycles of steel St E 36 at various stress

amplitudes in the rotating beam test 1)

Samples in the initial status and after various treatments

Type of

treatment

0

1

2

3

4

5

6

7

8

9

10

11

235

8,00389ZI1

Stress amplitude,

245

6,08636T__ 8,00126X11

260

6,59988

± oa in N/mm2

275

6,37840 6,91318

6,18921

7,21580XI1

5,85003

7,94734111

5,65031

6,53908

6,01284

5,57749

6,11694

5,75891

5,80414

294

5,45788

5,69020

5,41830

5,61805

5,93702

5,35025

5,63649

5,66839

5,24055

5,53148

5,62839

5,52244

343

4,5563c11

1) G. Ullrich, J. Kamber

Umlaufbiegeversuche fUr VertrHglichkeitsuntersuchungen im SALAMO-Projekt, PB-ME-78/01, 20. 1. 1978

- 24 -

Ok 4* Ok C

5 *» u •* m *» c • •H *J • If 3 3 E 0 fH a -H • z « • > u o> 3 C h a -H •

** ** «4 « «4 o +» m

o • u <o • c -* • a O JZ >> 4i m O 3

C +» ** •* K O 4>

• • u m m tt >-* h 3 m E v *• 3 -H -H B •-< -P

a -H S § c +»

• • •* • JC o a *»

M • v c 1 " " *» a a •H 3 a W O -1 « -H a 9 « § •5 > no

VII

•

1

CM

1 v. Z

c • H

CJ o •M

« • 5 • 3 ** • H

a am

pl

• a M •P 09

CO Ok

«o r»

Ok k©

Ok m

Ok

*> C

• of

atm

a

a a > H fr» *»

> M •n r» •-i 10 in % •»

Ok

CM CM

M

o «e r» Ok ce * m

m m i-i

m m % kO

M M M CM «n

8 •

O

m m m CM «o o*

m

CM •H Ok •-t O % «o

#-l

t-t

• o «o o> •*

Ift

m 10 CM •n kO » •o

CM

> kO •»

O ^ rt o OCM *> 10 « » •n m

CM

r» «o CM •-I « kO

«n

> ot «n **«n M Ok o. r-t • r« » *

«n m

O • kO O r* » kO

<r

r* t-i •n n co O r» « M» kO

*> «> •n m

Ok CM CO M» •ft O r» Ok Ok CO

* » •ft Ift

m \o

•H tf> CO *-» *» %

tft

•n CM 0 •H »-l »

10

i* (o

o •-I C0 A W *

•n

Ok m r» *4 •n »

kO

Ok

8 t*. 0-t kO » m

<n •H

co CM ^C %

kO

o <-** »M

Table VIII Logarithms of the number of cycles of the aluminium alloy Al-Mg3 at

various stress amplitudes in the rotating beam test 1)

Samples in the initial status and after various treatments

•

Type of

treatment

0

1

2

3

4

5

6

7

8

9

10

11

123

7,04155?" 3,00031±XA

128

6,20167 8,00379Aii

Stress

132

5,53529

6,41913

5,59660

5,75205

5,85126

5,84572

5,58659

5,99913

5,71349

2 amplitude, ± aa in N/mm

137

5,69984

147

5,51188

5,39094

5,44248

5,37475

5,32838

5,27184

5,46090

5,30320

5,51983

5,35984

162

5,09342

172

4,77085 4,79239

196

4,49136

Table IX Fatigue strength and fatigue limit of the investigated metals in the

initial status

Metal

A

B

C

D

Equations of the regression lines in the range of fatigue strength depending on stress amplitude

2 X = + oa » Stress amplitude,N/mm

Y - log N, N » number of cycles

Y = -0,02205 x + 11,785

Y - -0,02063 x + 11,81734

Y - -0,05598 x + 9,76448

Y - -0,02518 x +9,23022

Range of fatigue strength depen­ding on stress amplitude

104 £ N i 2tl06

104 £ N < 7,2«106

104 i N < 9»106

U0 4iN£ 1,1»106

Fatigue limit, N/ram*

248

240

50

126

Range of fatigue limit

N a 2«106

N 2 7,2-106

N i 9'106

N i 1,1«106

- 27 -

manometer for pressure measuring and recording /

thermocouple for temperature measuring and recording

valve for charging and discharging with ammonia or methylamine, respectively

stainless steel autoclave

Durabla-seal

ammonia or methylamine

CaCl2-8 NH3 or MgCl2*5CH3MH2

sample

beaker

teflon disc as sample holder

teflon ring

copper plate

thermocounle for automatic control

heating plate

Fig 2 Experimental arrangement for the autoclave experiments, 0.5:1

u

<u u 3 « <tf

90-

80"

fif»_

^ r . _

40~

30-

20-

in _ Q —

7_ fi —

^ —

• » _

- -~l

1 :

2 :

3 : 1

1 ' ' ' 1 1

12.6 ± 1,8°C

70.4 ± 2,7°C

L29.5 ± 3,4°C

HH,-liguid

-1 I I I '

, 9.4 ± 0.4 bar

, 14.2 ± 0.4 bar

, 15.4 ± 0.7 bar

1

+

/ NH,-vapour CaC1,•8NH,

1

j

/

/

-

2

NT. / ?•* y / c

/

•> /

r I

7

i

/

/ f

CaCl„'2NH, 4. j

/

/ f

d

/ f

"™Z"

/ f

3

ro 00

- 30 - 20 - 10 0 10 20 30 40 50 60 70 80 90 100 110120130140150 •+ °C

Fig 3 Experimental c o n d i t i o n s in the autoc lave experiments with CaCWNH,

- 29 -

o o o 6 o o o ot j \co s VD in -=r

o o oo>co c- vo in ^r

acq 'aanssaaj

CM

- 30 -

u m XI

^r • O

+i

CO » *H

* o

o vo • i - i

+i

O * CO

•-I

u « XX

ot

• o +1

\o * o

*» CJ

o * . r-f

+1

* * 00

r^

>-i

« Xi

m . *r

+i

CO

^ •- I

^ o

0 ro • O

»-i +i

r* * O*

•-I r<i

in i

O

< CO

0 c (0 o 0 «0

0)

c •H e 10 <H >. Xi 4* 0 c o > 1

•p

3 o 10

in

aueoap £ 00T/2HN€H0 &

31 -

Fig 6

Steel samples, StE 36

after about 20O0 hours at differ­

ent temperatures in

MgCl2/CH3NH2

sample on the left: room tenperature

sample in the middle: 80°C

sample on the right: 180°C

1.2 : 1

Fig 7

Aluminium samples, Al-Mg 3 ,

a f t e r about 2000 hours at d i f f e r ­

ent temperatures in

MgCl2/CH3NH2

sample on the l e f t : roan tenperature

sample in the middle: 80°C

sample on the right: 180°C

1.2 : 1

Fig 8

Steel samples, StE 36, after

about lOOO hours in

MgCl2/CH3NH2/CH3(CHj)gCH3

sample on the left: 18°C

sample in the middle: 78°C

sample on the right: 172°C

1.2 : 1

Fig 9

Aluminium samples, Al-Mg 3,

after about 1000 hours in

MgCl2/CH3NH2/CH3(CH2> gCH3

sample on the left: 18°C

sample in the middle: 78°C

sample on the right: 172°C

1.2 : 1

» « lO lO V • > W «w » » IO to 9> • • " • «

">* T» *o To Tj J. * * tj V> To a To T» To * i ^ Pig 10 Fatigue strength of the metals in the initial status and after treatments in calcium chloride/ammonia and in vacuum (type of treatmenti 0,1,2,1,4 and 5)

!09»

t

* , 5

ft 0

5 5

5.0

4 S

«.?

\ # \ \

\ 1 \ - * »S '-

l

\

\ \

Al W.5

\°

\

\ > • «

\ *

# \

\

St 37

\ \

\ \ \ \

7.0

IOBN — «D

c •

6.5 *

6.0 w o

E 5,5 JI

>> c *J e E

•8

5.0

«.?

t

6.9

5.5

5,0

«.S

4.?

c <

^

^

i

l untreated samples ) treated samples

*!-•>? 3

, » 95 t

\ \

I \

o

\

X \ - \ V

fl\

\ < i

\ °

St E 36

\ > * 95 i

\ \

\ \

\ '

\

^

\

5.5

5,0

4,5

U E 3 a a c c> a E

w

3

u • a >

w a

2 a a 3

6,0 -a *• c

a

a

JC

* > 0> e a b *» a

< 7 •*

?0 50 too 150 ?00 ?50 300 , , Pi/mm2

350

— ~ ( J * (j» 9i a* o* ^ * * — — • — ^ ^ ^ w _ • „^

7M V o a» o a i T ^ o r o t n o ui o ^ se °

Fig 12 Fatigue strength of the metals in the i n i t i a l status and a f u 4 various -treatments in magnesium chloride/methylamine/decane (type of treatment: 0,9,10 and 11)

^ L . j h ^ * - . - i _ * W ~ i r e . . . .*. .r ••»_• =• __ _ „ , ^ . ^ _ ^ • • " « i - » • « . * -

unetched, 5 ,5 : 1 unetched, 100 : 1 etched, 100 t 1

F i9 13 Steel St37 and StE 36 after 2152 hours at 180°C in magnesium chloride/methylamine (treatment 8)

- <*~ •. . . . -,;•' . . • ' . • , • m.. r

' . * • ' • • . — • • - • ' - ' • ' • • — , ~ • ' . < » • • ' •»?

' • . : • • • • » , ." • • . > . v * - . v. '• »'

unetched, 100 : 1

•"""T*Vr'•>.»•• • n r « n w t-V—*-Ay.*

' * ~ * * * * * — N * h . % j A ^

etched, 100 : 1

1048 hours a t 172°C in magnesium chloride/methylamine / decance (treatment 11)

- 38 -

«*... .+.""

• Al-Hc 3

unetched, 5,5 : 1 etched, 100 : 1

Fig 15 Pure aluminium Al 99,5 and the aluminium a l l o y Al-Mg 3 a f t e r

2152 hours a t 180°C in magnesium chloride/methylamine ( treat-

ment 8)

39 -

V̂v#-' • 3 *

^.: Al 99,5

Al-Mg 3

unetched, 5,5 : 1 etched, 100 : 1

Fig 16 Pure aluminium Al 99,5 and the aluminium alloy Al-Mg 3 after

1048 hours at 172°C in magnesium chloride/methylamine/decane

(treatment 11)