Quality appraisal of copper-steel composite materials

copper-steel composite materials are based on the core principles of interface metallurgical bonding and functional gradient design. Through processes such as explosive welding, hot-rolling composite or electroplating deposition, the excellent conductivity of copper and the high-strength properties of steel are synergized. They are widely used in fields such as power equipment, electronic components, chemical containers, and shipbuilding. In the power industry, it is used for transformer winding conductive plates and grounding devices; in the electronics field, it meets the low resistance and heat dissipation requirements of high-frequency connectors; in chemical equipment, it ensures the corrosion resistance and thermal conductivity of reactors; in shipbuilding, it achieves the anti-bioadhesion and corrosion resistance of seawater piping systems. Compared with single metal materials, copper-steel composite materials have the characteristics of high interface bonding strength, controllable conductivity, and gradient adaptation of thermal expansion coefficient. They are the core materials of multi-functional composite structures of high-end equipment.

Zhongke Testing is a product quality appraisal service organization registered with the court. It can provide copper-steel composite material quality appraisal services. It has a professional appraisal team and advanced instruments and equipment to provide fair and accurate appraisal results for copper-steel composite material quality appraisal.

With the expansion of the application of copper-steel composite materials in key scenarios, quality dispute cases have increased significantly. The judicial dispute focuses on:

1, performance index dispute: whether the interface bonding strength meets the standard, conductivity deviation;

2, material defects: uneven copper layer thickness, interface oxide inclusion;

3. Process problems: Improper control of explosive welding energy caused microcracks, and the out-of-control temperature gradient of hot-rolled composites resulted in insufficient grain boundary diffusion;

4. Contract performance disputes: Composite process type, base material material and technical agreement did not match.

The technical methods for quality identification of copper-steel composite materials mainly include:

1. Chemical composition analysis: Use a spectrometer or atomic absorption spectrometer to analyze the content of copper and steel to determine whether the composition of the material meets the standards.

2. Metallographic analysis: observe the microstructure of the material through a microscope and analyze the microstructure, phase composition and defects of the material.

3. Mechanical performance testing: including tensile test, bending test, impact test, etc., to evaluate the strength, toughness and plasticity of the material.

4. Electrical performance testing: including resistivity testing, conductivity testing, etc., to evaluate the conductive properties of materials.

The applicant, a power equipment company, and the respondent, a material factory, signed the "Explosive Composite Copper-Steel Conductive Plate Procurement Contract", agreeing that the interface shear strength is ≥180MPa. After installation, the copper layer warped, causing the contact resistance to exceed the standard. The manufacturer argued that it was caused by excessive installation stress.

identification analysis results:

The quality analysis expert group discussed and comprehensively analyzed the relevant information of "copper steel composite materials", contract technical agreements, on-site investigation case materials and other data, and made the following quality analysis Opinion:

The interfacial shear strength of the copper-steel composite material involved in the case is only 135MPa, and there is a continuous CuO inclusion zone in the interface area (accounting for 8%); the thickness of the copper layer fluctuates by ±0.15mm (agreed ±0.05mm); the explosion welding parameter record is missing, and the metallography shows that no continuous diffusion layer is formed.

The appraisal conclusion concluded that the material factory did not control the process parameters and interface cleanliness according to the agreement, and material defects were the main cause of the failure.

copper steel composite material quality appraisal report mainly includes the following contents:

1. Client information

2. Appraisal equipment information

3. Appraisal basis (standards, power of attorney, etc.)

4. Identification method