FAULTY FUSIONS IN LARGE-SIZE EXPLOCLAD SHEETS AND DETONATION

PARAMETERS OF EXPLOSIVES

L. B. Pervukhin and O. L. Pervukhina

Defects which are caused with instability of a detonation of a charge

local tear-out of clad material

CHANGE OF THE DETONATION VELOCITY OR ATTENUATION

CHANGE OF EXPLOSIVE DENSITY

Mode of self-extending explosive process with the lowered power allocation

Curvature of the detonation front

Sharp local change of welding parameters (pressure, impact velocity, collision angle)

worm-holes, faulty fusion clad metal

Local closed fault of shock-compressed gas area

Defects of continuity

worm-holes , faulty fusions

Sinuosities, cracks

Requirements to explosive for explosion welding

• Detonation velocity explosive of in flat charges from 20 to 120 mm should be in the thickness no more than 3000 km/s.

• Explosive at charge packing should not will be condensed and compressed.

• Detonation stability of a flat charge remains on the big areas to 20 sq.m.

• Low cost explosive and possibility of its preparation in day of use from components not being an explosive material.

TNT +ammonium nitrate (1:1) ammonium nitrate +diesel oil (3%).

Research of detonation process of the large-sized flat charges having a thickness close to critical for given explosive

Thickness layer of inert material (sand)changed from dкр/2 to dкр

Material , Thickness, mm

Explosive Thickness, mm Durability of joint, MPa

Continuity of layers joint %Explo

siveSand

Ст.3 + Ст.32,5 +20

TNT +ammonium nitrate

1:1

30 0 218 100

15 15 310 100

8 22 125 90

8 8 0 0

10+08Х18Н10Т100 + 12

ammonium nitrate

+diesel oil (3%)

80 0 410 100

50 30 430 100

30 50 350 80

Estimation of size of losses at a detonation of charges

The closed cover of the explosive chamber allows to estimate change of energy which is allocated at a charge detonation on its deformation.

Camera deformation measured in several points

TNT +ammonium nitrate (1:1) ammonium nitrate +diesel oil (3%).

Thickness layer of inert material (sand)changed from dкр/2 to dкр

Acoustic influence on environment

Measurement of a sound level by the device spent directly on range at performance of regular works on explosion welding of preparations in the size 4200х1200х120 mm (400 kg of a mix).

Sound level on distance of 1200-4000 m at explosion of explosive charges with inert material is less in 4 times, than without it.

TNT +ammonium nitrate (1:1) ammonium nitrate +diesel oil (3%).

Thickness layer of inert material (sand)changed from dкр/2 to dкр

Research technique of mixes of ammonium nitrate +diesel oil

• Definition of influence of type of ammonium nitrate and percentage of diesel oil on quality of their mix;

• Establishment of dependence of detonation velocity from quantity of diesel oil, a thickness of explosive and presence of an inert material (sand);

• Experimental check of a mode of explosion welding on large-sized charges Definition continuity of layers joint , structures and joint durabilities.

Microporous ammonium-nitrate + diesel oil from 2 to 16%

Ground ammonium-nitrate + diesel oil from 2 to 16%

Granulated ammonium-nitrate + diesel oil from 2 to 16%

Ammonium-nitrate structure

Microporous ammonium-nitrate granules Granulated ammonium-nitrate granules

•Wetting of the granulated ammonium-nitrate by diesel oil is carried out by filling of roughnesses on a granule surface owing to what ability of their wetting is insignificant. Process of mixing is at a loss and there is a stratification in the course of storage. •Ammonium-nitrate crushing before mixing with diesel oil considerably raises its wettability, however such mixes are condensed and compressed;•Presence of a microporous in structure of ammonium-nitrate considerably increases the surface area of a granules of that allows to impregnate. It allows to impregnate and keep well diesel fuel for a long time.

Influence of thickness of charge and sand for

velocity of detonation of mix NH4NO3+diesel oil

Thickness Thickness

of chargeof charge

Detonation rate

Contents Contents of diesel of diesel oiloil

Influence of the contents of diesel oil on detonation rateof mix NH4NO3+ diesel oil

Under a sand layer the mix with the maintenance of diesel oil of 4 % steadily detonates in thickness of 20 mm with a velocity of 1480 km/s in charges in length of 6 m.

Detonation rate

Under a sand layer

Without sand

Conclusions• For stabilisation of detonation process of large-sized flat

charges it is necessary to place a layer of an inert material on their surface. It reduces probability of occurrence defects.

• Use as explosive at explosion welding of a mix of the granulated microporous ammonium-nitrate + diesel oil allows to reduce

to a minimum application industrial explosive, to mechanise process of mix preparation, to provide high quality of welding for the account of stability

of structure and charge density on all its surface. Speeds of a detonation of these mixes in the studied range

of thickness of a charge are close to optimum from the point of view of joint formation at explosion welding.

Explosive

Bulk density,

kg/m3

Explosive layer

thickness, mm

Detonation rate, m/s

Microporous ammonium-nitrate + diesel(2-8%)

740 60 1770-2910

Microporous ammonium-nitrate + diesel(4%)

740 40-80 2080-2740

Microporous ammonium-nitrate + diesel ( 4%) +sand

740 20-80 1480-2400

Granulated ammonium-nitrate + diesel oil(2-6%)

900 80-100 2500-3400

Ground ammonium-nitrate + diesel oil( 2-6%)

850-900 20-50 2500-3400