What Is Clad Metal?

Metal composite materials refer to composite materials formed by using composite technology or multiple metals with different chemical and mechanical properties to achieve metallurgical bonding at the interface, which greatly improves the thermal expansion, strength, fracture toughness, and impact toughness of a single metal material. , Wear resistance, electrical properties, magnetic properties and many other properties, so it is widely used in products widely used in petroleum, chemical, marine, metallurgy, mining, machinery manufacturing, power, water conservancy, transportation, environmental protection, pressure vessel manufacturing, food , Brewing, pharmaceutical and other industrial fields.

Metal composite

(1) Definition of nouns: It is a combination of two or more substances with different phases in a physical way, and the advantages of each component are extracted to form the required structural material. These materials must also meet the following four conditions:

a. Must be made by humans (this is different from some natural composite materials that already exist in nature, such as wood).

b. Must consist of two or more substances with different chemical properties.

c. Each constituent material has a volume of three degrees (because it is not the case if the sheet is pressed or welded).

d. Must have some special properties, and such properties are not originally owned by each constituent substance.

(2) Composite materials include three major areas: Metal Matrix Composites (MMC's), Ceramic Matrix Composites (CMC's) and Polymer Matrix Composites (PMC's include thermoset and thermoplastic). Polymer composite materials, in which carbon fibers are used in composite materials and have better physical properties than traditional glass fiber composite materials, are particularly known as ACM Advanced Composite Material.

1. The production methods of composite materials at home and abroad mainly include solid-liquid phase bonding method, solid-phase bonding method, laminated hot rolling method, diffusion compression bonding method, overlay welding method, overlay welding hot rolling method, etc. The most common solid-phase bonding methods are explosive welding and hot rolling.

The development and application of the method of explosively welding stainless composite steel plates have started a little later at home and abroad. Developed in the 1960s, mature in the 1970s, and entered commercial production.

2. The method of rolling stainless composite steel composite steel plates has attracted the attention of some researchers as early as the 1930s. Rolling composites are divided into hot rolling composites and cold rolling composites. This composite method has high yield, high dimensional accuracy, and mature technology and equipment, but often requires surface treatment and annealing strengthening treatment.

example:

Titanium-steel composite plate GB 8547-87

This standard applies to titanium-steel explosive composite plates or explosion-rolled composites for corrosion-resistant pressure vessels, storage tanks and other applications.

A Appendix A for Metal Composite Materials

Heat treatment system for composite plate

(Supplement)

When stress relief annealing is required for the composite plate, the heat treatment system is implemented as follows:

a. Heat treatment temperature: 540 ± 25 ;

b. Holding time: less than 3h;

c. Heating and cooling rate: 80 200 / h.

B Appendix B for Metal Composite Materials

Ultrasonic flaw detection method of titanium-steel composite plate

(Supplement)

This method uses steel or stainless steel as the base material, titanium as the composite material, a total thickness of more than 8mm, and a single-layer composite explosion and explosion-rolled composite plate ultrasonic flaw detection method.

B. 1 General requirements

B. 1.1 Purpose is mainly used to detect the degree of adhesion between the composite material and the substrate of the composite board.

B. 1.2 Method category This standard specifies the use of longitudinal pulse reflection method (or multiple pulse reflection method) for ultrasonic flaw detection. Either contact method or water immersion method can be used.

B. 1.3 Requirements for Flaw Detectors Flaw detection operators should reach the level of non-destructive inspection personnel at the ministerial level or equivalent to the third level or above; personnel who issue and interpret inspection reports should reach the level of personnel at the ministerial level or equivalent. Level.

B. 1.4 Flaw detection surface.

B. 1.4.1 The surface of the composite board shall be free of other scales, such as oxide scale, oil stains and rust.

B. 1.4.2 The surface roughness Ra of the flaw detection surface should not be greater than 5 m.

B. 1.4.3 Under the specified flaw detection sensitivity, the noise level of the material is not greater than 5%.

B. 2 Flaw detection equipment

B. 2.1 Flaw detection equipment

B. 2.1.1 Use pulse reflection ultrasonic flaw detector. The flaw detection instrument shall comply with the technical performance indicators specified in ZBY230-84 "General Technical Conditions for Type A Pulse Reflection Ultrasonic Flaw Detectors".

B. 2.1.2 Ultrasonic thickness gauge can also be used.

B. 2.2 Probe

B. 2.2.1 Use straight probes with round or rectangular crystals. Can also use dual crystal oblique probe and thickness measurement probe.

B. 2.2.2 The crystal size is generally 10-30mm, the rectangle is wide (10-20) mm × length (15-30) mm, and the frequency is 2.5-10MHz.

B. 2.3 When the coupling agent is used for flaw detection, clean tap water can be used as the coupling agent, and water glass, soluble oil, glycerol, etc. can also be used.

B. 2.4 Comparative test blocks

B. 2.4.1 The comparative test block shall be made of a composite plate material with the same or similar material thickness, acoustic performance and surface state as the composite plate under investigation.

B. 2.4.2 The form and size of comparative test block A and test block B are shown in Figure B1.

B. 3 flaw detection

B. 3.1 Selection of flaw detection surface According to the surface state of the plate being tested, the thickness of the composite material, the acoustic impedance and the appearance shape, it is decided to detect from the composite material surface or from the substrate surface.

B. 3.2 Flaw detection sensitivity

B. 3.2.1 Flaw detection sensitivity is determined according to the shape of the plate being tested.

B. 3.2.2 Adjust the flaw detection sensitivity using a comparative test block.

B. 3.2.3 When detecting from the composite material surface, place the probe on the fully bonded part of the comparative test block A, so that the primary reflected wave from the bottom surface of the composite board substrate appears on the phosphor screen, and adjust its amplitude to the full scale of the phosphor screen. 80%.

B. 3.2.4 When detecting from the substrate surface, place the probe on the defect center of the comparative test block B, so that the defect reflected wave appears on the fluorescent screen, and adjust its amplitude to 80% of the full scale of the fluorescent screen.

B. 3.2.5 When the multiple pulse reflection method is used, place the probe on the fully combined part of the contrast test block A, or on the defect center of the test block B, so that there are three bottom echoes on the horizontal baseline of the flaw detector screen, or Three defect echoes, adjust the amplitude of B1 or F1 to 80% of the full scale of the phosphor screen. (The amplitude of B2, B3, F2, F3 is determined by the thickness of the material).

Note: B1, B2, and B3 are the first, second, and third reflected waves of the fully bonded part, respectively. F1, F2, and F3 are the first, second, and third reflected waves at the defect site, respectively.

B. 3.3 Determination of non-fitting area.

B. 3.3.1 Definition of non-adhesive zone During the detection process, if the starting pulse signal widens and the bottom pulse disappears or the defect pulse widens and moves forward, the area is regarded as a non-adhesive zone.

B. 3.3.2 Judgment of non-adhesion zone When detecting from the composite material surface, if the reflected echo from the bottom surface of the substrate completely disappears, accompanied by repeated reflection signals from the interface between the composite material and the substrate The site can be considered a non-adherent area.

When detecting from the substrate surface, if the reflected echo from the bottom surface of the composite material completely disappears, accompanied by a reflection signal (ie, a defect wave) from the interface between the substrate and the composite material, the part can be considered as a non-adhesion zone .

B. 3.3.3 Scope of non-fitting area

B. 3.3.3.1 When detecting from the composite surface, as the probe moves arbitrarily, the bottom surface reflection wave drops to 50%, which is the range of the non-adhesion zone.

The width and length of the non-adhesion area are shown in Figure B2.

Determine the distance moved by the probe. The length inside the wafer is the length or width of the non-adhesion area.

B. 3.3.3.2 When detecting from the surface of the substrate, adjust according to the type B contrast test block. The range of the non-fitting area is determined by the half-wave height method.

To measure the moving distance of the probe, the center distance of the wafer is the width and length of the non-adhesion area.

B. 3.4 Calibration of Flaw Detection Sensitivity

In the process of flaw detection, due to some reasons. B. The height of the bottom echo or defect echo and B. 3.2.3, B. 3.2.4, B. 3.2.5 When the debugging state is different, the sensitivity of the flaw detector can be corrected so that the amplitude of the bottom surface echo or defect echo reaches 80% of the full width of the fluorescent screen.

B. 3.5 flaw detection speed

During manual detection, the scanning speed of the probe must not exceed 100mm / s.

B. 3.6 Defect records

B. 3.6.1 Record continuous or discontinuous points where the bottom echo found during the scan is less than 50% (not including the reduction caused by poor contact due to surface conditions) and record the Represent on the board and calculate its

area. The reduction of the bottom surface echo of the base material or composite material due to its internal defects should not be considered.

B. 3.6.2 The calculation of the area of the non-adhesion area is approximate.

B. 3.6.3 Formula for calculating fit rate

t = (S-SF) / S * 100% (B.1)

Where: tfitting rate;

Stotal area of composite board, cm2;

SFTotal area of non-fitting area, cm2.

B. 3.6.4 Non-fitting rate calculation formula:

f = SF / S * 100% (B.2)

Where: f-non-fitting rate;

Sf total area of non-adhesion area, cm2.

S total area of composite board, cm2;

B. 3.7 When the thickness of the composite material is less than 2mm, a thickness measurement probe or a double crystal oblique probe can be used to detect from the composite material surface.

B. 3.7.1.1. When using a dual crystal oblique probe, if the bottom echo moves forward or disappears, and the interface pulse widens, this area is a non-adhesive area.

B. 3.7.2 When detecting with a thickness measuring probe, the thickness of the fully bonded and unbonded parts of the composite board is directly displayed by the thickness gauge.

B. 3.8 Probe Report

B. 3.8.1 Make a detailed record of the inspection and fill in the inspection report.

B. 3.8.2 The inspection report includes:

a. Commissioning unit, commissioning date, commissioning number, contract number, material name, specifications, status, category and inspection conditions;

b. The size and location of the non-fitting area;

c. Undetected area:.

d. The circumstances that must be explained;

e. Inspection date

f. Signature of flaw detector.