《In the previous article》In , we have established a knowledge framework for the properties and applications of metal materials and sorted out the core steps of scientific material selection. However, the theory needs to be tested in practice.

This article will focus on the actual combat link: how to use advanced detection technology to provide reliable data support for material selection decisions? How to balance performance and cost in a project? And through real cases, the consequences and solutions of improper material selection are revealed.

Composition analysis: Through spectroscopy and chemical analysis, determine whether the content of various elements in the material meets the requirements of the grade composition limit.

2, mechanical properties: including tensile strength, hardness, toughness, ductility, etc., through tensile testing, impact test evaluation.

3, electrical conductivity, thermal conductivity: directly affect the heat dissipation design, such as mobile phone shell need to take into account the thermal and electromagnetic shielding.

Chemical stability: through salt spray test, acid and alkali soaking simulation of the actual use environment (such as insulation cups need to be resistant to water, tea, coffee corrosion).

Fatigue performance: Evaluate the life of the material under the cycle stress and the key performance indicators of long-term safe service (such as car chassis parts).

Microstructure: The metallographic microscope observes the size and distribution of grain and determines the process defects.

Laboratory commonly used metal material detection methods and their applicable scenarios:

Technical comparison:

OES and XRF are suitable for rapid field inspection, but XRF has superior non-destructive properties;

ICP-OES/MS has higher precision, but requires complex pre-processing, and is suitable for laboratory precision analysis.

Taking the thermos cup as an example, the selection of materials needs to be considered comprehensively:

Safety: Food grade stainless steel (such as 316) needs to meet the GB 9684 standard austenitic stainless steel.

Corrosion resistance: 316 stainless steel can withstand acidic beverages (such as lemon juice) for a long time because of molybdenum.

Thermal conductivity: The double-layer vacuum structure can reduce thermal conductivity, but the thermal conductivity of the material itself needs to be moderate.

Cost: 304 stainless steel cost-effective, 316 is suitable for high-end demand.

A smart watch shell: use titanium alloy (lightweight + sweat corrosion resistance), through XRF to verify the uniformity of the coating.

New energy vehicle battery housing: the use of aluminum alloy (lightweight + excellent heat dissipation), through the salt spray test to ensure environmental corrosion resistance.

In coastal equipment, 304 bolts are stress-corrosive cracking, and there is no Mo (PREN=19) in 304, which cannot resist chloride ion erosion → 316 containing Mo (PREN=25).

Copper connector plug force attenuation, phosphorus bronze contact after high temperature and high humidity elasticity decline; through component analysis found that the Sn content is insufficient (<5%), insufficient aging, and then recommended to increase Sn to 6-8% (such as C5191).

Aluminum alloy shell intergranular corrosion, the product in the anodized after the corrosion pattern; detection component analysis Fe impurity exceeding the standard (>0.5%) to form the Al3Fe cathode phase, accelerate local corrosion → control Fe <0.2%.

The selection of metal materials is a subtle art that combines material science, testing technology and engineering experience. From accurate component analysis to rigorous performance verification, rigorous data support is required at every step.