2025 Steel Purchasing Guide: Carbon Steel vs. Stainless Steel Cost Comparison, How to Avoid Pitfalls in Engineering Material Selection?

1. The core difference between carbon steel and stainless steel

（1）Composition and performance

①Carbon steel: Carbon content 0.02%-2.11%, high strength but easy to rust, suitable for structural parts (such as building beams and columns).

②Stainless steel: Chromium content ≥10.5%, strong corrosion resistance, suitable for food equipment and marine engineering.

（2）Cost comparison

①Price: Carbon steel is about 4000-6000 yuan/ton, stainless steel is about 15000-25000 yuan/ton (average price in March 2025).

②Maintenance cost: Carbon steel needs regular rust prevention treatment, and stainless steel has lower long-term cost.

2. Project material selection and avoidance guide

（1）Environmental adaptation

①Stainless steel (such as chemical pipelines) is preferred in high humidity/corrosive environments.

②Carbon steel (such as storage shelves) can be used in dry indoor environments.

（2）Supplier traps

①Beware of "inferior quality": using 201 stainless steel to impersonate 304 (can be preliminarily judged by magnetic testing).

②Require material certificate (MTC) and check the brand and standard (such as GB/T 20878).

3. Case Analysis

A bridge project: Q235 carbon steel was originally planned to be used, but 316L stainless steel was used because it is close to the coast. The service life was extended by 20 years and the total cost increased by 15%.

Summary: The purchase of steel requires a comprehensive assessment of the initial cost, maintenance costs and service life. It is recommended to consult a professional engineer to obtain a customized solution.