Quality Objection Case: Pressing In The Oxide Scale
Case Overview:
A customer purchased a 4.5*1520mm*C hot-rolled NO.1 steel coil from a steel plant. During the cut-to-length flattening process, the customer found that there was an intrusion of oxide scale on the surface and filed a quality objection complaint to the steel plant.
Case Study:
With the continuous expansion of stainless steel in industrial and civil applications, stainless steel hot-rolled NO.1 steel coils are directly produced on the surface of the substrate, which is widely used in decorative decoration, loading, and unloading vehicles, storage tank equipment, etc.
Customers not only require excellent physical properties and geometric dimensions for stainless steel products but also have higher requirements on the surface.
1 From the definition and morphological analysis of hot rolled oxide scale:
There are strips with a certain degree of continuity along the rolling direction on the surface of the strip, in the form of loose needles, loose sand, or flaky iron oxide, which can occur in different types of stainless steel.
The main reason: the effect of high-pressure descaling is not ideal, and the primary iron oxide scale is not removed by descaling. The rolling temperature in the process is too high, and the secondary oxide scale is pressed into the surface of the stainless steel strip during rolling.
2 Seen from the surface of the frosted substrate at a fixed length on site:
There is flaky iron oxide intrusion along the rolling direction on the surface of the strip (picture 1 below).
The frosted surface without oxide scale pressing (photograph 2 below).
3 This quality objection case tells us
For mature steel companies, the difference in core competitiveness does not lie in equipment and production capacity, but in their internal management capabilities. The market is the only standard for testing product quality.
Process Result
After friendly discussions with customers, a one-time compensation is given, and customers are advised to sell according to the apparent needs of different user groups.