Exploring the Science of Explosive Welding

What is Explosive Welding Plates?

Nickel Plated Copper Sheet, that is, the metal composite plate produced by the explosive welding method (explosion welding method), explosive welding plate generally refers to the explosion from the metal composite plate. An explosive welding composite plate is a type of composite material plate manufactured by using explosive forming technology, and its manufacturing process involves multiple steps like explosive forming, metal composite, and surface treatment.

Metal explosive welding technology is really a composite material processing technology that utilizes the huge energy generated by the instantaneous generation of explosives to instantly composite 2 or more kinds of similar or dissimilar materials together, which technology can weld metals with various properties, especially those which are not dissolved, into one piece.

In comparison with the direct rolling composite method:

(1) loading speed, that is, the loading process is instantaneous ;

(2) Placed on the workpiece high-pressure pulse load, loading stress is a lot higher than the yield strength from the metal material;

(3) The bonding area shows wave-like metallurgical bonding characteristics;

Explosive welding composite plate history
Explosive composite discovery is the earliest in 1944, the American L.R. Karl (Carl) in a dynamite explosion test, accidentally found two bits of 1-inch diameter, thickness of .035 inches of thin brass discs, due to the sudden impact from the explosion and was welded together. In fact, in World War II, people in the repair of wounded tanks, but also often found that tilted impact to the tank on the shrapnel is going to be firmly welded to the tank armor phenomenon, just throughout the war individuals have no time to analyze it.

In 1947, the Siberian branch from the Soviet Academy of Sciences, the famous scientists M.A. Lavrentsev in the study of polymer bombs to penetrate the armor also found this phenomenon, within his dissertation formally known as “explosive welding”.

In the area of welding, the welding of different materials, like steel and aluminum, steel and copper, is technically very hard. And huge welding depth of welding is also very hard, if you want to use conventional welding, shielding welding and other welding methods is going to be two 40mm thick wide plate welded right into a 80mm thick wide plate, it is estimated that no one will do. However, the explosive welding is perfect to solve the 2 problems at the same time.

Explosive welding composite plate principle production method
Explosive welding is really a composite plate manufacturing method that mixes one or more materials right into a single piece using explosives because the energy source. Following the explosion of explosives, the blast products form a high-pressure pulse load, directly working on the compound plate, promoting the top-speed movement from the compound plate, within the collision point of the compound plate and the substrate tilt collision, combined with violent plastic deformation and the formation from the jet, the jet takes away the surface of the contamination layer, so the welded metal flat plate having a clean surface in contact with each other at high temperatures and high pressures, the two kinds of plate will realize the strong metallurgical bonding.

Explosive welding composite plate-specific production methods:

1. Explosion molding
Explosion molding is the first step within the manufacture of explosive welding composite plates. Within the explosion forming process, explosives in certain conditions instantly detonated, the resulting high-pressure gas is going to be pushed to the opposite side from the metal plate mold, so the metal plate instantly to achieve the desired shape and size. This forming method is described as high precision and high efficiency.

2. Metal composite
Within the explosion molding, the need for metal composite. This task is usually utilized in explosion welding or explosion crimping and other methods, 2 or more metal plates with the explosion energy combined together to create a composite material. Throughout the metal composite process, a metallurgical reaction occurs between different metals, forming a powerful metallurgical bond.

3.Surface treatment
Surface therapy is usually needed to improve the surface quality and corrosion resistance from the explosive welding plate. Commonly used surface treatment methods include spraying, plating, chemical plating and so forth. These methods can increase the wear resistance, corrosion resistance and aesthetics from the composite plate.

Explosive welding composite plate production process, although simple, flexible production, however the technical requirements are high, hard to accurately control, the parent material properties (toughness, impact properties, etc.), explosives properties (bursting speed stability, safety, etc.), the initial parameters (the quantity of explosives per unit area, the base compound plate spacing, etc.) and the dynamic parameters (collision angle, the compound plate collision speed, etc.) from the choice and system coordination from the composite plate from the finished product yield and quality features a direct impact.

The composite interface consists of direct bonding area, melting layer and vortex. Atomic diffusion exists at the bonding interface, and severe plastic deformation with work hardening occurs in the bonding zone. The bonding surface features a wavy structure, that is beneficial to the improvement of bonding strength and tensile strength.

Explosive welding plate performance
Explosive welding explosive welding plate is not going to change the chemical composition and physical state from the original material, according to the actual needs from the composite material to be individually processed in to the required optimal state.

Explosive welding plate application performance is very good, can withstand cold, hot processing without changing the thickness from the combination of materials compared to the combination of composite materials is very high strength, usually higher than the lower side from the combination of materials, that is unattainable by other technologies. The composite material is not going to delaminate or crack during subsequent heat treatment, leveling, cutting, rolling, spinning and other production.

For room temperature and 550 ? heat treatment of carbon steel surface layer (close to the interface layer) has serious deformation caused by fibrous tissue and several fine particles, the heart from the organization of ferrite plus pearlite; stainless steel interface for the second phase of point-like organization, the heart from the needle-like organization. But by 650 ? treatment of carbon steel samples close to the interface section of small particles from the organization disappeared (that may occur decarburization), the grain becomes coarse, the heart from the organization is still ferrite plus pearlite, but could not seen in the business from the slip line produced by deformation; as well as in the stainless steel interface there are a lot of small black particles, titanium steel composite plate could be the decarburization of chromium carbide particles formed after the benefits of the material right into a whole, giving full play to the usage of different metal materials, and greatly save rare and rare materials, and the usage of different metal materials. The usage of performance greatly saves rare metal materials, thus reducing the production price of equipment.

Weak demand and oversupply in Asia have pushed steelmakers in the region to develop supplies of low-carbon steel and iron, especially because the Jan. 31 reporting deadline for the European Union’s Carbon Boundary Adjustment Mechanism (CBAM) draws nearer, market participants said.

The situation is further complicated because other Western countries, namely the U.S., want to introduce similar policies.

A Singaporean trader said, “Asian steel producers have not slowed down production and want to increase output, therefore we expect capacity additions to outpace demand growth, particularly in the post-epidemic recovery period.” . “…… Products have to go somewhere. Producers can export to Europe, but that means they need to offer low-carbon products at huge discounts.”

Asia’s path to decarbonization has already seen several breakthroughs, particularly as policymakers have focused on various climate targets and dealt with public and private stakeholders to build up low-carbon technologies.

These investments have enabled steelmakers to discover commercially viable technologies and reliable sources of clean energy, namely direct reduction of iron from scrap or gas, or shifting to electric arc furnace steelmaking, that features a lower carbon intensity compared to blast furnaces.

Paolo Frediani, senior analyst at Fastmarkets, said the market is reacting to the steadily growing demand for green steel, given the quantity of pipeline investment.

“CBAM will certainly give a major boost [in developing a green steel supply chain], but despite the advanced regulation of steel emissions in Europe, the green steel premium is largely supported because more and more end-users are attempting to reduce their overall carbon footprint,” says Frediani. “Although this drive is stronger in some regions than the others, it is becoming a global phenomenon.”

Explosive composite explosion welding advantages
Explosive composite this new process, new technology in a short time to acquire rapid development and wide application, the primary reason is that it has the following four advantages:

(1) A number of composite materials can be combined it can make the melting point, strength, coefficient of thermal expansion and other performance differences are extremely disparate metal combinations to achieve composite. Like aluminum – steel, titanium – steel. Currently has realized the composite material combination of over 300 kinds, that is incomparable to other methods.

(2) Excellent material properties
Composite plate from the general design principle is to satisfy the mechanical properties from the structure from the base material, compound plate to meet the corrosion or wear resistance and other properties. Therefore, compared with just one metal plate, the composite plate makes full use of the best performance from the substrate, and the compound plate not just has the required high strength but also has excellent corrosion resistance, wear resistance, and other properties of high production efficiency.

(3) High production efficiency/high bond strength.
Explosive composite in a really short time, and can be welded over a large area, an area of up to 20 square meters or more, within the composite interface, dissimilar metals with the metal bond to achieve inter-atomic bonding is normally not under the a minimum of the strength of the composite material constituting the respective parent body.

(4) Good economy
The usage of explosion welding technology to create composite plate products have both the corrosion resistance from the compound layer and other functional characteristics and both the strength of the grass-roots level and plastic toughness indicators, you can save precious metal resources, reduce costs.

Application of explosive welding plate
Composite materials produced by the explosive welding method continues to be widely used in petroleum, chemical, shipbuilding, electronics, electric power, metallurgy, machinery, aerospace, atomic energy and other industrial fields. The composite plate is carbon steel being a substrate, single-sided or multi-faceted with precious metals being a double layer of high-efficiency energy-saving new composite materials, composite by explosion welding of special processing technology, both with the corrosion resistance of precious metals, wear resistance, but also with carbon steel, good weldability, molding, extensibility, thermal conductivity; explosive welding plate is now widely used within the petrochemical industry, metallurgy, salt production and alkali production, the water industry, Nuclear industry.

Shipbuilding
In shipbuilding, explosive welding plates may be used to manufacture hull structures, decks, bulkheads, etc. Because of its high strength and good corrosion resistance, the explosive welding plate can effectively improve the durability and repair life from the ship.

Aerospace
Within the aerospace field, explosive welding composite plates may be used to manufacture airplane fuselage, wings, engine parts, etc. Because of its good thermal stability and high strength, explosive welding composite plate can improve the performance and safety of aircraft.

Construction Industry
Within the construction industry, explosive welding composite plates may be used to manufacture structural parts for bridges, high-rise buildings, highways, and so forth. Because of its high strength and good corrosion resistance, explosive welding composite plate can improve the safety and repair life of buildings.

Automobile manufacturing
In automobile manufacturing, explosive welding composite plates may be used to manufacture body structural parts, engine parts, and so forth. Because of its lightweight, high strength, and good thermal stability, the explosive welding plate can improve the performance and safety of automobiles.

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