methods of manufacturing swords in the middle ages

7/25/2019 Methods of Manufacturing Swords in the Middle Ages

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METHODS O F MANUFACTURE O F SWORDS

IN MEDIEVAL EUROPE: ILLUSTRATED

BY THE METALLOGRAPHY OF SOME EXAMPLES

BY

ALAN

R.

WILLIAMS, Ph

D.

DU RIN G the Dark Ages in Europe, the manufacture of the swords

kno wn as


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Im ~r o v em en ts n hardness could then be obtained bv suitable heat-

treatment, although the connection between carbon content and harden-

ability was imperfectly und erstoo d. Heterogen eous blades we re hope-

fully quenche d to produce hardness in useless places.

In his valuable discussion of forty-one swordblades of Rhenish origin

dated from the 6th-12th centuries

A. D.

Anteins

3)

gives analyses of

some of them . Nine (6 th -lo th centuries) were made entirely from

pattern-welded . Six (9th -11 th centuries) had only a thin p attern

welded layer welded 'on to the surface of the blade for decorative pur-

poses. Th e others, which included Ulfbehrt swords (9 th -l t h centuries)

had r laminated structu res.

One of the swords he analysed consisted of three bands whose car-

bon content varied from 0.1 to 0.870 . I t has been heat- treated to

produce w ha t A nteins calls


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tw o operations in th e reverse o rder w ill, of course, prove fruitless.

(This

might explain th e resultant sw ord described in Panseri s p aper ).

Th e overall carbon con tent of an edge carburised blade may well have

been lower than that of one made by piling together several small pieces

carburised individually. Bu t, on the other hand, a blade mad e from a

single bar m ight well be stronge r (dep end ing on the skill of th e lamina t-

ing) , wou ld certainly be cheaper (Anstee an d Biek took fo rty-th ree hours

to forge a pattern-welded blade) and would probably lend itself more

conveniently to heat-tre atm ent. All bu t one of th e sword s discussed

here had been hardened by some for m of heat-trea tm ent. Th e exception

had an exceptionally high carbon content.

Th e method s of hea t-treatm ent employed in the Middle Ages included:

( i ) Full quenching (t o form an all-martensite struc ture) . If the

overall carbon content was low, a full quench without tempering might

be employed.

( i i )

Slack quenching (not quenching fast enought to produce an all-

martensite ptructure, but a mixture of martensite, and other products;

bainite and/or pearlite ). Th e sw,ord could be plunged into oil, boiling

wa ter or some othe r quenching medium less drastic than cold wa ter. Th e

hardness would be less than that of an all-martensite structure, but its

brittleness wou ld also be less. Tem pering wou ld not be necessary, unless

the carbon content was high. An interrupted quench (i . e. plunging int o

water for a few seconds, withdraw ing and the n quenching again) might

well produce a similar mixture of transformation products.

( i i i ) Slack penching and tempering. Reheating a slack-quenched

steel would yield a mixture of products, some of which would be dif-

ficult to resolve, and m any of which w ould h ave becom e aggregates of car-

bide particles whose origins could not be diagnosed. I t is possible that

some such process was responsible for forming Piaskow ski s


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Methods i) , iii) and iv) do not correspond to any modern industrial

process, although a form of slack-quenching has been advocated on grounds

of cost.

10)

The preferred modern method of heat-treatment is a full

quench to produce an all martensite structure) followed by reheating to

temper it. This is a difficult operation to control in the absence of any

means of measuring temperature or time. The two-stage process of a

full-quench followed by a tempering was evidently not used for any of

the sword blades discussed in this paper at least, no microstructure which

can be identified solely as tempered martensite was found) but it appar-

ently did come into use in the sixteenth century. This two-stage process

was also then applied to the hardening of steel armour. This is the

subject of my present research, and

I

hope to discuss these developments

in a future article.

R E F E R E N C E S

ANSTEE,.

W . a n d BIEK , L, < A study in p attern welding>>,

Medzeval Archae-

ology

19 58) , 71, which contains a full bibliography.

KLINDT-JENSEN,

ctKeltisk Tradition: Romersk Jernaldem,

Aaboyer f. Nordzsk Oldkyndzghed

og Hzsfovze

1952). BEENY

H .

H. and COLLINS,. E . F. , < Report on pattern

welding on a Spearhead of the Viking Period),,

Man

1950), No. 199.

PANSERI,.,

,

Journal of th e Iron Steel Instztu te

1968), 563.

PIASKOWSKI,

. , < Themanufacture of medieval damascened knives*,

Journal of

the Iron Steel Institute

1964), 561.

CARPENTER,

. and

ROBINSON,

. M., < The metallography of some A ncient

Egyptian implements,,

lo ur na l of th e Iro n Steel Irrsrzlulr

1930), 417.

COGHLAN,. H., < Notes of Prehistoric Early Iro n in the Old Worldn,

1956), 150.

THEOPHILUS,

tDe diversis art ibu w, Ed . and transl . Dodwell , C. R. 1961).

There are apparently only three papers describing medieval swords metallur-

gically.

PANSERI,

., aRicerche metallografiche sopra una spada da guerra

del

XI1

secolos,

Documentz e contrzbutz pev la storza della metallurgza I

1954 ), 41. This sword was edge carburised only and not quenched.

HEN-

GER,G.

W., ctMetallography of iron base samples>>,

ulletzn Htstovzcal Metal-

lurgy

4 1970), 50. A 16th century sword was edged carburised an d

quenched

LANG,

. and

WILLIAMS,

. R., The hardening of iron sword s)>,

Jouvnal

o f

Archaeologzcal Sczence

2 1975), 199. A 15th/ l6 th century So-

lingen sword was also edge-carburised and quenced.

Allan R. Williams

Gladius XIII (1977), pp. 75-101

ISSN 0435-029X

Digitalizado por InterClassica

http://interclassica.um.es

Consejo Superior de Investigaciones Cientficas

http://gladius.revistas.csic.es


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9.

BURNS,. L.,


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1 arts of section ?ot

carbon-free Iro n alr-cooled steel hardened steel

pearllte) vaTl0us mlcro-co ns~ltue nts)

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S W O R D N o .

Wurttemberg Landesmuseum, Stuttgart)

Sword with the inlaid name VLFBER CH)T,

10th century? or 11th perhaps from Rhineland

This sword was examined on an already broken section.

Half of this

cross-section was capable of being polished for photomicrography.

It

ossible construction

will be assumed that the other half is the same since the sword is two-

edged, and therefore probably symmetrical about a longitudinal axis.

The half-section shows four distinct layers which produce different

colours on etching and show slag inclusions at their junction. Com men -

cing from the edge an d working tow ards the centre) there is layer

A

a

brown-etching material) whose microstructure contains mostly pearlite

with needles of cementite within, and a network of cementite around, the

pearlitic areas.

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This gives way abruptly to layer B wh ich etches d ark blue-grey) whose

inicrostructure also contains very f ine pearlite and ceme ntite.

Th is gives way to layer C wh ich is brow n-etching) and there is a wh ite

band along the frontier of layer B and C. This band also extends some

Ulfbercht

ection through

7

on edge

way tow ards th e cen tre of the blade along the median axis.

Slag inclu-

sions, of irregular shape, are near to this band but do not coincide exactly

w ith it. I t may be the remains of a layer of flux used in welding the

layers together.

Layer

C

consists mostly of pearlite.

Layer C gives way

abru ptly to layer which is m ottled in appearance, an d consists of pearl-

ite areas with a netwo rk of ferrite surrounding them.

Allan R. Williams


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This blade has been mad e by forgin g several small pieces of steel

together.

The different appearance of layers A and B compared with C

and D may be due to their having been welded from four separate pieces,

or it may be due to differing carbon contents. Since there are no visible

Ulfbi.r: li sw ord (W iir:te mb erg L. M , )

X 320 71 12

V er y f tn e pearlzte az d cementzte fr om area h

welds along the frontiers of A with B and

C

with

D,

it is not possible

to

be

dogmatic.

So at least four elements have gone into the welding of th- blade,

i. e. two on each side although these in turn may have been made from

several smaller ~i e c e s. . e. four on each side.

Th e carbonLco nt&t varies from about 0.7 in the centre to about

1.0 near the edge.

The blade has evidently been air-cooled after fab-

rication, and no ateempt has been made to harden it by heat-treatment.

Ind eed , in view of th e high C %, such treatment would have been very

difficult.

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X 32

71 17

A t t he we ld. No te slag inclusion, and light streak perhaps

le f t by f l ux f rom welding.

lfbercht sword

X

1280 71 16

Ver y fzne pearlzte and need les of cem entzte deposzted wzthzn

th e penrlzte areas Ar ea c on sectzon

Allan R. Williams


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SWORD No.

Sword Ea 92. Leiden Wapenmuseum)

Probably made 1150-1200; blade is inscribed

BENEDT

DNS DSM

This blade was alreadv broken. so that it was ~ ossible o remove a

sample from the entire cross-section of the blade.

h

section was found

T h e tw o outer dark -etch lng) layers are of hardened

steel.

T h e central layer is of carbo n-free iro n.

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to show three distinct layers.

The central layer consists mostly of ferrite

with a large corrosion crack running down the middle.

The two outer

layers an d these are shaped so that they also form the cutting edges)

consist principally of a dark-etching material whose boundary with the

ferritic centre is sharply defined.

There are also numerous slag inclusions which are largely to be found

at these boundaries.

This sword has evidently been made by welding together a bar of

almost carbon-free iron and two bars of medium-carbon steel, and then,

T h e

centre s ncasly all

ferrite

after shaping, heat-treating the result to harden it.

Neither the carbon

content nor the method of heat-treatment can now be deduced with anv

certainty.

T he microstructure of the o uter layers consists principally of a dark-

etchin g irresolvable material which is probably ba inite. Th is is associated

w ith proeutectoid fe rrite, some of w hich is in a spiny form . The re is

also some martensite visible.

Th e sword has bee n slack-quenched, perhaps cooled in oil or some

other mild quenchant. There has been time for ferrite to form at the

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The bovder between the hzgh-carbon and low-carbon aveas is

vevy sharp.

a 92

X 24

T h e hardened zone contatns martensite,

a

dark-etching mate-

rzal, and near the cen tre ) spzny ferrzte. No te th e long slag

zncluszon.

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austenite grain boundaries before the austenite has started to transform,

initially into bainite or perhaps very fine pearlite) and subsequently the

remainder into martensite.

Average Hardness centre) 200

VP

3 0 g. load) hardened zone)

650 VPH.

Martenszte, dark-etching material probably b ainit e) and spiny

ferrite.

S W O R D N o . 3

Swiss National Museum, Zurich

I N .

7006

word Blade, perhaps of 13th centuvy

This swo rd was examined on a section already broken .

I t was heavily

corroded, bu t areas around both cutting edges were intact see sketch).

The microstructures of both these areas contain ferrite near the centre

which gives way gradually to hardened zones. Th ese contain an irresol-

vable constituent as well as areas of a granular material which preserves

an acicular outline.

Allan R. Williams


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This sword has evidently been made by carburising its edges after

fabrication from wrou ght iron and then heat-treated to harden it .

Th e precise nature of this heat-treatment cannot now b e d etermined

IN.

7006 X

1

64.17

Surface of blade ts at to p of photogv aph

Note gradual

carbuvtsation

since the carbon conten t is unk now n. But the acicularity suggests tha t

the steel was originally quenched from above the uper critical temperature

but cooled only at a rate fast enough to produce mostly ba inite rather than

martensite.

Allan R. Williams


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T he irresolvable areas may be of a different carbon conte nt which has

led to a different transformation product being formed.

Th e blade has then been reheated to temper i t and the bainite ? ) has

form ed fine carbide granules. Th ese occur in some places as a ce tw or k

and in others as an acicular aggregate.

IN.

7 6 X 16 64.16

l tempered structure whzch shows the ovtgznal aczculav struc

ture outlzned by the austenzte grazn boundavles N ot e slag

zncluston

Allan R. Williams


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SWORD No. 4

Ziirich)

Fragment of a single-edged dagger excavated from Schnabelburg de-

stroyed 1308); LM 6369; studied by examining its section where it had

been broken.

Because of the irregular corrosion that this blade had undergone only

isolated parts of the section yielded metallic surfaces for examination.

However, the two areas visible were at the sharp edge and the back of

the blade see sketch) so that the nature of the corroded parts can be

deduced.

At OW magnification, two zones can be distinguished.

That next to

the surfaces of the blade consists of dark-etching material with a fine mi-

Bo:h

LM

6 69

X

400

63.15 18

crostructure.

The inner portion of the blade is white-etching ferrite.

At

higher magnification, the hardened zone may be seen to contain a

91

Allan R. Williams


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granular structure which is probably tempered martensite, and an irres-

olvable material which is probably bainite. Very little ferrite is visible

in this zone, but it becomes more plentiful as the centre is approached.

Reheated martenstte ?).

The carbzde partzcles

outlzne the orignal struc-

tuve uaguely.

There are a number of slag inclusions but they do not correspond to the

borders of the hardened zone.

T he surv iving part of th e back of the blade consists entirely of fer rite.

Th is blade has been fabricated in carbon-free) wrou ght iron, and the

cutting edge case-carburised to form a steel edge.

Either the back was

not packed in the carbonaceous material, or else it was subsequently

decarburised. The former seems more probable.

The edge was not welded on, for the change in carbon content is not

abmpt nor is there a line of slag inclusions corresponding to a weld .

The blade was then hardened by heat-treatme nt .

I t was probably fully-quenched i. e. cooled rapidly from above the

Upper Critical Temperature) since no proeutectoid ferrite seems to have

separated, and formed a mixture

o

martensite, and other products such

Allan R. Williams


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as bainite, depending on the local carbon content.

It was then probably

reheated to temper it , bu t th e precise nature of the operations performed

cannot be deduced with certainty.

Hardness approx. 3 20 V P H .

LM.

6369

X l600

63 21

Cdrbide particles probably formed by heating bainite or mar

tensite

SWORD

No.

5

(Musge d Art e t d Histoi re , Geneva. 162 c)

Sw or d Blade of th e early fourteen cen tury

This bro ken blade was exam ined on the section already visible. Th is

surface was very corroded, but areas of unattached metal were still visible

(see sketch). Tho se areas nearer th e centre of the blade we re found to

have microstructures consisting entirely of ferrite. Those near the surface

had a dark-etching, fine structure.

This appears, at high magnifications,

to consist of num erous irregular granules. Th is might be tempered mar-

tensite or bainite or nodular pearlite.

This sword has probably been made by case-carburising a wrought

iron blade, and then heat treated to harden it . This heat-treatment may

Allan R. Williams


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Sword 162c [Geneva X 7

51.1 , la

Uncorroded iron lig ht) and steel da rk ) in the centre.

Sword 162c X 1280 54 36

A

granular structure zs visible.

Allan R. Williams


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well have been a slack quench i. e. a cooling from the upper critical tem-

perature insufficiently fast to give an all-martensite structure but fast

enough to yield a mixture of martensite, bainite, and perhaps pearlite.

I t has probably then been reheated.

Average hardness approximately

6 VPH

SWORD No.

6

City Museum, Koln )

Dagger

W

24 9 Early 14 th century

This fragment was examined on an already broken section.

Corro-

sion has left only part of the cross-section intact, b ut enough m etal remains

to show the overall s tructure. T he central parts have a microstructure

consisting mainly of fe rrite, wh ich gives way gradually t o hardened areas

near the surfaces. T he re is a dzstznct gradzent in th e t rans it ion f rom th e

core to the hardened outer zones. Th e microstructure of th e latter con-

tains spiny ferrite, bainite and martensite.

This dagger has been case-carburised after fabrication and then hard-

ened by rapidly cooling from above the upper critical temperature.

The higher-carbon areas have been transformed by the quench into

martensite.

The areas of lower carbon content have transformed to bai-

Allan R. Williams


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nite and other products. I t may then have been rehea ted but it is

not

now

possible to say definitely.

ll Dagger W .

249

X

96

79.41 49 57

From a lower carbo n area: spiny ferr ite and an irresolvable material th at mig ht be

baznite.

Allan R. Williams


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Hardness varies from centre out to edge) from about

250

to 66

VPH

Average hardened zone) 47 VPH.

SWORD No.

7

Historical Museum, Frankfurt)

Sword X6522/ON29 of pevhaps 14th century

This sword was examined on an already broken section. I t proved

possible to detach half the section from the centre to one edge) for exam-

Frankfurt sword X6522

T h e l ight band in the centre o

the section consists of grains

o f

ferrite

Allan R. Williams


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ination . Th e microstructure show ed a centra l layer consisting of ferrite

and another structure which may be bainite.

This central layer is sur-

rounded by a dark-etching area wh ich extends to th e surface on both sides.

This microstructure s not clearly resolvable everywhere; but does, in pla-

ces, contain tempered martensite and an acicular material which might

be bainite.

Spiny ferrite is also visible.

There are numerous slag inclu-

sions in lines parallel to the outer surfaces.

They are concentrated in

the middle of the dark-etching area and do not coincide with the division

between this area and the ferritic centre.

f this sword was made by wrapping a piece of high-carbon steel

around a piece of low-carbon steel and forging them together, then the

result m ust have been heated above th e upper critical temperature) for

Allan R. Williams


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some considerable time to allow the carbon dissolved in the austenite time

to diffuse away from the line of slag inclusions.

More probably, the blade was fabricated and then case-carburised.

It

has then been hardened by heat-treatment.

This method cannot

now be deduced with certainty but it probably consisted of a quenching

(i. e. rapid cooling from A3 temperature) which transformed the higher-

carbon austenite areas into martensite and the lower-carbon areas into

bainite. I t may then have been slightly reheated to temper it (perhaps

by residual heat).

S W O R D N o .

8

(MusCe d Ar t e t d Histoi re , Geneva . 1 6 3 ~ )

Swo rd blade of the early fifteen th century

This broken blade was examined on the section already visible.

Th e

surface was very corroded, bu t areas of unattached metal w ere still visible

(see sketch).

A large area near the centre has a microstructure consisting

Sword 63c X

60

53.24 27

T h e dark area

is

the hardened outer zone

entirely of ferrite, but a smaller area near the surface shows a hardened

zone.

O n closer exam ination, this latter area is foun d t o consist of three

different layers.

O n the inner side there is an area of ferrite. Th is

gives way gradually to an increasing proportion of light-brown-etching

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Sword 16 (early 15th cent.) found at Geneva

areas of a material which is probably bainite.

This layer gives way

abruptly to a dark-brown-etching and fairly uniform layer.

There is a

very distinct frontier between this zone and the rest of the section.

At high magnification, tempered martensite mixed with an irresol-

vable material (perhaps tempered bainite) can be seen in this dark layer.

Th ere are nume rous slag inclusions visible throu gho ut the section. Th is

sword has been m ade by case-carburising a wrought blade, and then heat-

treated t o hard en it. Th is may have been a


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cooled most rapidly, being in contrast with water, and the austenite has

transformed to principally) martensite. The sword has then been with-

drawn from the water. The heat left in the centre of the blade has been

sufficient to temper the martensite formed in the outside as the blade

Probably tempered bainite Bo th

structures from the hardened zone

and also lower-carbon) areas have been

as cooled down. The inner

cooled less drastically and formed bainite.

Approximate hardness ferritelbainite):

275

VPH; tempered mar-

tensite):

650

VPH.

ACKNOWLEDGEMENTS

The author would like to acknowledge the support he has received

from the Leverhulme Trust which has made his research possible; and

to the British Council and the British Academy whose generosity has made

his foreign visits possible. He would also like to express his gratitude

to those museums and curators who have co-operated so willingly. I n

this case his thanks must go to Dr. H Schneider of the Swiss National

Museum, Zurich, Dr.

V

Himmelein of the Wurttemberg Landesmuseum,

Stuttgart, Dr.

H

Stubenvoll of the Historical Museum, Frankfurt, of the

City Museum, Koln, and to MM. C. Bosson and

H

Otenin-Gerard of

the Museum of Art and History, Geneva. He is also grateful for the

advice of Dr. R Priestner and Mr. D. Ryder of the Department of Met-

allurgy, Manchester University.

Allan R. Williams


ISSN 0435-029X

methods of manufacturing swords in the middle ages

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