Chromium-based stainless steel quality appraisal

chromium series stainless steel is based on the core principles of chromium element passivation film formation and alloy composition ratio. By optimizing chromium content, carbon control and heat treatment process, it achieves synergy between corrosion resistance and mechanical strength. It is widely used in chemical equipment, medical equipment, food processing, marine engineering and other fields. In petrochemical equipment, it is used for lining acid-resistant pipelines and reactors; in the medical industry, it meets the biocompatibility requirements of surgical instruments; in the field of food machinery, it ensures the hygiene and safety of contact surfaces; in the marine environment, it resists chloride ion erosion. Compared with ordinary stainless steel, chromium-based stainless steel has high resistance to pitting corrosion, excellent high-temperature strength and good formability, and is a core material for harsh corrosive environments.

Zhongke Testing is a product quality appraisal service organization registered with the court. It can provide chain bucket elevator quality appraisal services. It has a professional appraisal team and advanced instruments and equipment to provide fair and accurate appraisal results for chain bucket elevator quality appraisal.

1, performance indicators dispute: whether the saline-resistant mist test cycle met the standard and whether room temperature resistance strength met the plate number;

1. Material composition analysis: Use a spectrometer or chemical analysis method to measure the chemical composition of equipment materials, and compare it with the contract agreement or industry standards.

2. Mechanical performance testing: The tensile strength, yield strength, elongation at break, hardness, impact toughness and other mechanical properties of the equipment are measured through tensile test, hardness test, impact test and other methods, and compared with standard requirements.

3. Corrosion performance test: Place the equipment in a specific corrosive environment, such as an acidic solution or salt spray environment, observe its corrosion resistance, and evaluate whether it meets the usage requirements.

4. Process defect detection: Use non-destructive testing technology, such as ultrasonic flaw detection, magnetic particle flaw detection, etc., to check whether the equipment has cracks, pores, inclusions and other process defects.

A medical device factory of the applicant signed a "316L Stainless Steel Plate Purchase Contract" with a steel factory of the respondent, agreeing that the Mo content is 2.5%. During production, rust spots were found on the surgical forceps after sterilization. The manufacturer argued that the cleaning agent was too acidic.

Identification analysis results:

The quality analysis expert group discussed and comprehensively analyzed the relevant information, contract technical agreements, on-site inspection case materials and other data of "Chromium Series Stainless Steel" and made the following quality analysis Analytical opinion:

involved plates have a Mo content of only 2.1% and a Cr content of 16.8% (agreement ≥ 17%); the weight loss of intergranular corrosion by nitric acid method reaches 4.2g/m²·h (standard ≤3.0g/m²·h); the cold rolling process does not control the rolling direction, resulting in a Δr value of 0.7.

The appraisal conclusion concluded that the steel plant failed to control the ingredients and processes in accordance with the agreement, and the lack of material corrosion resistance was the main cause of corrosion.

chromium series stainless steel quality appraisal report mainly includes the following contents:

1. Client information

2. Appraisal equipment information

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

4. Identification method