CA1107466A - Explosive cladding - Google Patents

Explosive cladding

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Publication number
CA1107466A
CA1107466A CA319,876A CA319876A CA1107466A CA 1107466 A CA1107466 A CA 1107466A CA 319876 A CA319876 A CA 319876A CA 1107466 A CA1107466 A CA 1107466A
Authority
CA
Canada
Prior art keywords
plate
flyer
layer
cladding
explosive
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA319,876A
Other languages
French (fr)
Inventor
Peter W. Jackson
David B. Cleland
David K. C. Anderson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Imperial Chemical Industries Ltd
Original Assignee
Imperial Chemical Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Imperial Chemical Industries Ltd filed Critical Imperial Chemical Industries Ltd
Priority to CA319,876A priority Critical patent/CA1107466A/en
Application granted granted Critical
Publication of CA1107466A publication Critical patent/CA1107466A/en
Expired legal-status Critical Current

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Abstract

Abstract:

A method of applying a surface layer across a surface layer or joint between cladding layers on a clad metal plate or plates comprises forming a shallow chamfer along each opposing cladding layer edge and positioning over the said chamfers a corrosion resistant metal flyer-plate having a shallow generally V-shaped configuration, optionally applying a buffer layer of transmitting medium placed on the outside surface of the flyer-plate, further superimposing an explosive layer upon the cladding and buffer layers and detonating the explosive layer so as to weld the flyer-plate material at least to the cladding layers. Advantageously a metal groove may be formed in the base metal layer of the clad plate to facilitate positioning of the flyer-plate, the groove wall conveniently being extensions of the cladding chamfer surfaces.
The method facilitates an assembly of a cladding strip and explosive layer over a joint between clad metal plates in any orientation and gives joints of high quality between the cladding layers on the plates.

Description

~7466 : Improvement.s in and relating to explosive claddi.n~
This invention relates to explosi.ve claddi.ng of structura]. metal members by a corrosion resistant metal layer and is particularly, although n~t exclusively, applicable to strip cladding across ~egions of fusion welded joints between two or more clad plates.
There is an increasing use of corrosion resistant clad plate in the construction of vesse].s and structures for use in corrosive environments such as those cxperienced in chemi.cal prant. The plate employed is usually steel, clad with a relatively thin layer of corrosion resistant metal such as, for example, titani.um, and since it is not normally possible to fusion weld this layer to the base metal it is usually formed by explosive welding. The technique of forming this material is well known in the art.
When lar~e vessels are to be constructed it is often necessary to join two or more such clad plates together and this presents difficulties since it is not possible to fusion weld the complete clad plates.
Thus to fabricate butt joints between titanium clad steel plates it is necessary to machine off the titanium cladding for a small distance so that fusion welding of the steel plates may then be effected without interference from the titanium cladding layer.

74~6 It is then necessary to repair the ga~ in the titanium cladding to restbre the corrosion resistant ]ayer. ~ne known method is describe~d in a Paper entitled "Explosion Clads" by A H Holtzman - Proceedings oi' Seminar o~ NATO Advanced Study Institute on High -~ Energy Rate Working of Metals - Oslo 1964, page 51~.
- This metho~ involves the use of a silver,titanium or copper insert which is laid within the gap a~d then bridged by an overlaid strip of titanium which is fusion welded to the titanium cladding along each side of the joint region. 'rhe insert acts as a fiLler ` material to prevent fatigue failure of the titanium strip and attendant welding. Similar techniques are employed for joining clad plate made in other such metallurgically incompatible combinations such as tantalum/steel and zirconium/steel.
This so]ution is expensive due to the"cost of the insert employed and the high degree of welding skill required to perform the joint.
It has also been pro~osed in United Kingdom , Patent Specification No. 986,435 to explosively weld a corrosion resistant layer across a fusion welded zone in clad metal plate by assembling over the fusion weldecl zone a strip of cladding metal and an overlying layer of explosive material and detonating the explosive along one edge. For best results the cladding strip was disposed at an angle to the clad ; metal base plate but the assembly is difficult to , assemble accurately and the resultant weld is not uniform over the fusion welded zone.
The object of this invention is to provide a less expensive,convenient method of surface cladding joints between clad metal plates which produces a high integrity weld.
In accordance with the present invention a method of applying a surface layer across a surface layer or joint between cladding layers on a clad metal plate .

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. ' or plates comprises forming a sllal.low chamfer along each opposi.ng cladding layer edge and positioning over the said chamfers a corrosion resi.stant metal flyer-plate having a shallow generally V-shaped configuration, o~tionally applying a ~uffer layer of transmitting medium placed on the outside surface of the flyer--p].ate, further superimposing an explosive layer upon the flyer-plate or buffer layers and detonating the explosive layer so as to explosively weld the flyer-plate material at least to the cladding layers.
The optimum angles of the chamfers and the flyer-plate legs relative to the clad base plate for optimum welding may be calculated by known methods described, for example, in the following papers:-Papers by H K Wylie, P E G Williams and ~ Cross].andentitled "An Experi.mental Investigation of Explosive Welding Parameters" - Proceedings of the first Syrnposium on the use of Explosive Energy in Manufacturing Metallic Materials of New Properties, Marianske Lazne, 1970, published hy the Institute of Industrial Chemistry,Pardulice, Czechoslovaki.a and "Further Experimental Investigation of Explosive Welding Parameters" - Proceedings of the Third International Conference of the Center for High Energy Forming, Denver 1971.
Paper by R H Wittman - Proceedings of the Second Symposium on Explosives Working of Metals at Marianske Lazne, 1973, Pages 153-167.
Paper entitled "Some Aspects of Exp].osive Welding in Different Geometries" by M D Chadwick - Proceedings of The Welding Insti.tu-te Select Conference on Explosive Welding, Hove 1968.
In some cases i.-t is advantageous to form a groove in the base metal layer o~ the clad plate centrally between the chamfered edges of the cladding ~746~

-- l --layers, in order to facilitate positioning of the flyer-plate. The groove may conveniently be formed simultaneously wlth the chamfers of t!1e cladding layers and effectively extends the chamfer surfaces.
The invention is preferably applicable to the joint region of clad metal plates where two base metal pla.tes have been fusion welded together.
The flyer-plate may advantageously have integral extensions which become detached by the explosion, whereby high quality welds up to the flyer-plate edge are achieved. The extensions are conveniently defined by longitudinal grooves formed at the commencement of the extensions or by bending the extended flyer-plate along a line at the commencemellt of the extension in a direc-tion outwardly from the base plate.
In a further modification each leg of the flyer-plate is provided with a pair of ang].ed portions to provide for a partial weld to occur to the base or target as well as the cladding portions.
The flyer-plate may be spaced apart from the base or target plate in order to modify the explo~ive weld between the flyer-plate and the base pl~te.
Preferably a plastic explosive, such as Metabel, (Registered Trade Mark) having a high detonation velocity is employed in the form of a flexible sheet.
Other features of the invention will become apparent from the description which follows of three specific embodiments.
The invention will now be described, by way of example only, with reference to the accompanying drawings in which Figure 1 shows a diagrammatic cross-section of one embodiment in accordance with the invention;
Figure 2 shows schematically the resultant explosive weld achieved with the arrangement shown in Figure l;

:

.
, Fi,gure 3 shows a d-iagrammatis cross-section of an al~ernative embodiment in accordarlce with the invention.
Figure ~ shows schematically the resultan-t explosive weld acllieved with the arrangement show in Fj.gure 3.
Figure 5 shows a diagrammatic cross-section of a further embodiment in accordance with the in~ention.
Figure 5A is a modification of the embodiment of Figure 5.
Figure 6 shows schernatically the resultant explosive weld ac~hieved with the arrangement shown in Figures 5 and 5A.
' In the drawings like elements are designated by the same numeral.
In the embodiments shown in Figures 1-6 the invention is applied to the fusion butt weld region joining two flat steel base plates 1 and lA. The cla,dding layers 2, 2A are machined back for a short dis-tance from the weld region to prevent interference with the fusion we]ding process and shallow chamfers at an angle ~ are machined on the exposed ends of the cladding layers 2, 2A adjacent to the subsequently formed fusion weld ~one 6.
As shown in Figure 1 a rectangular flyer-plate 3 of cladding material compatible with the cladding layers 2, 2A is bent to a shallow generally 'V' configuration such that each side subtends an angle ~ and is closely positioned as shown. The sides may meet at an angle or on a radius along the apex. The angles ~ and ~ are determined on the basis of calculation of the required collision angle which provides the suitable set-up angle ~-R required for explosive welding to take place. The flyer 3 will also be curved in side profile along the weld when the weld is curved or circumferential.
The flyer-plate 3 is covered with a buffer layer 4 comprislng a transmittlng medium sucil as rubber and a l~yer of explosive medium 5 whlch is preferably a high detonation velocity explosive such as ~etabel.
In order t.o avoid distortion of -~he base plates l and lA it may be necessary to place the base plates on a matching anvil such as a heavy metal plate which resists the detonation of the explosive.
The explosive medium 5 is detonated in the direction of the ~usion weld seam, i..e. perpenclicu'ar to the section of the plate shown in Figure 1. The velocity of the flyer-plate 5 at impact is determi.ned by the e~plosive loading and detonation velocit:y of layer 5; the collision angle and collision point velocity are determined by the velocity of the flyer-plate 3 and also by the angle ~-~ and may be calculated fiom a know].edge of the prior art.
The form of the resultant weld after dressing, i.e. removing excess material, is as shown in Figure 2.
No weld occurs centrally, although in certain conditi.ons some welding may take place between the flyer 3 and the base 1, lA at some distance from the centre, but weldi.ng occurs along the sloping portions of the cladding, thereby effectively maintaining the continuity of the cladding across the joint regi.on.
The arrangement described above with reference to Figures 1 and 2 is suitable when the weld zone width is small. However, when the weld zone is wider the embodiment illustrated in Figures 3 and 4 may be employed.
Thus as shown in Figure 3 the extent of welding may be increased by forming an additional inclined portion 3B havi.ng an inclination of angle ~ to the target or base layers, 1, lA so that inclined portion 3A form an angle ~ with the base 1, lA and the portion 3B form a resultant angle ~-~ with the chamfers on the clad layers 2, 2A. The resultant :: ' 74~i~

weld after dressing is shown schematically in Figure 4 and it w,ll be seen that welding of the flyer occurs right across the joint surface except for a narrow centrai region, due to the normal impact and the low stand-off.
In the arrangement shown in Figure 5 the edges of the cladcllng layers 2, and 2A and the portion of the base 1 and lA adjacent to the weld 6 are machined at a chamfer angle a thereby forming a groove 7 above the weld 6, the angle ~ being the ~ppropriately choser. welding angle. The f1yer~ 3, with its sides including an angle 180-2~ is positioned with its apex in register in the groove 7.
On detonation of the explosive layer 5 the flyer is welded to the upper surface of the cladding layer 2, 2A as shown in Figure 6.
In the modified assembly of Figure 5A the flyer plate 3 advantageously has integral extensions 3C which can be coplanar with the flyer plate or bent upwards as shown. In addition the flyer plate 3 has longitudin~l grooves 8 at the commencement of the extensions.
The buffer layer 4 and the explosive layer 5 covers all the area of flyer plate 3 and extensions 3C.
The buffer layer 4 may also be locally thickened in the area immediately over the weld 6 for increased protection of the flyer plate in the region of the weld.
On detonation of the explosive layer 5 the extensions 3C become detached and the flyer is welded to the upper surface of the cladding layer 2, 2A, as shown in Figure 6, the extension promoting welds of high quality up to the flyer plate edge.
The invention described above has the following advantages:-The flyer or cladding plate 3 may be pre-formed with the buffer layer 4 and explosive charge layer 5 74~6 prior to welding and simple end jigs may be employed to maintain the required set-up geometry prior to detonation of the explosive layer.
Welding may be performed on curved seams by using shaped (curved) flyers, provided that the correct relative angles are maintained. ~ow~ver, final closure of a full circumferential weld may not be achieved because of pressure do~bling and overlap effects and therefore final closure of a small region only may require the more complex fusion welding technique to be employed.
The method in accordance with the invention is applicable to seams lying in any direction or or.ientation, e.g. vertical, horizontal, overhead or downhand.
~ xplosives whose detonation velocity fall within a wide range are suitable~ However, plastic explosives, such as Metabel which has a high detonation velocity, are preferred mainly on the grounds that they are readi.ly moulded to shape and will stay in position without further packag~ng being required.
It shou]d also be no-ted that an explosively welded seam can readily be inspected by ultrasonic techniques which are not applicable to fusion welded seams.

Claims (13)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A method of applying a surface layer across a gap between cladding layer edges on a clad metal plate comprising forming a shallow chamfer along each opposing cladding layer edge and positioning over the said chamfers a corrosion resistant metal flyer-plate having a shallow generally V-shaped configuration with the apex of the flyer plate facing the clad metal plate and lying between and generally parallel to the cladding layer chamfered edges and below the upper surface of the cladding layer, super-imposing an explosive layer upon the cladding layer and detonating the explosive layer so as to weld the flyer-plate material at least to the cladding layers on each side of the gap.
2. A method as claimed in Claim 1 wherein a groove is formed in the base metal layer of the clad plate centrally between the chamfer edges of the cladding layers, in which groove the flyer-plate is positioned.
3. A method as claimed in Claim 2 wherein the groove effectively extends the chamfer surfaces of the cladding layers.
4. A method as claimed in Claim 3 wherein the groove is formed simultaneously with the chamfers of the cladding layers.
5. A method as claimed in Claim 1 wherein a surface layer is applied to a joint region of clad metal plates where two base metal plates have been fusion welded together.
6. A method as claimed in Claim 1 wherein the flyer-plate has at least one integral extension which becomes detached by the explosion.
7. A method as claimed in Claim 6 wherein the extension is defined by a longitudinal groove formed at the commencement of the extension.
8. A method as claimed in Claim 6 wherein the extension is defined by bending the extended flyer-plate along a line at the commencement of the extension in a direction outwardly from the base plate.
9. A method as claimed in Claim l wherein each leg of the flyer-plate is provided with a pair of angled portions to provide for a partial weld to occur to the base metal plate as well as to the cladding portions.
l0. A method as claimed in Claim 1 wherein the flyer-plate is spaced apart from the base metal plate.
11. A method as claimed in Claim 1 wherein the explosive layer comprises a plastic explosive.
12, A method as claimed in Claim 11 wherein the explosive is in the form of a flexible sheet.
13. A method as claimed in Claim 11 wherein the explosive has a high detonation velocity.
CA319,876A 1979-01-18 1979-01-18 Explosive cladding Expired CA1107466A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA319,876A CA1107466A (en) 1979-01-18 1979-01-18 Explosive cladding

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA319,876A CA1107466A (en) 1979-01-18 1979-01-18 Explosive cladding

Publications (1)

Publication Number Publication Date
CA1107466A true CA1107466A (en) 1981-08-25

Family

ID=4113358

Family Applications (1)

Application Number Title Priority Date Filing Date
CA319,876A Expired CA1107466A (en) 1979-01-18 1979-01-18 Explosive cladding

Country Status (1)

Country Link
CA (1) CA1107466A (en)

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