[Quality objection treatment of steel coil grinding 8K surface not up to standard]
Case Overview
The customer purchased a batch of 0.75*515mm cold-rolled coils for deep processing and grinding of 8K surface, but after processing it was found that the surface could not achieve an 8K effect. The customer raised a quality objection to the steel mill.
Case Study
The steel plant immediately dispatched technicians to conduct on-site inspections. According to the cold-rolled substrates on site, there are slight oxide scale presses and scratches on the surface to varying degrees. After investigation, the batch of steel coils are sold as black coils, and then they are brought into the market after being pickled with local soil.
According to the observation of 8K grinding on the 2B cold-rolled surface on-site, the 8K grinding process with nitric acid and iron oxide red has a relatively low grinding cost. Generally, a mirror effect can be achieved after one pass of processing.
On the surface of the volume, communicate with users:
1. Hot rolling and cold rolling are two different rolling technologies. Hot rolling is fast-rolling at a high temperature after heating the billet. The cold rolling is to roll the hot-rolled NO.1 coil as the raw material at room temperature, and different rolling processes obtain different strip surfaces and geometric dimensions.
The surface quality, appearance, and dimensional accuracy of cold-rolled steel strips are better than those of hot-rolled steel strips, and cold-rolled steel coils are used as the base plate for deep processing of products to become high value-added products.
2. For the cold-rolled surface basically obtained by grinding 8K by hot rolling, if it is a hot-rolled NO.1 coil pickled by a steel mill, not all plate surfaces can achieve the effect of grinding 8K obtained by cold rolling and rolling.
At present, the ratio of cold-rolled strip steel to grinding 8K in major steel mills sold in the market is to verify the explanation.
3. There are high requirements for grinding an 8K cold-rolled plate surface: the surface of the substrate must not have rust stains, vibration lines, trachoma, roll marks, scratches, abrasions, creases, peeling, and other defects.
However, secondary quality defects such as peeling of the surface of the hot-rolled No.1 coil will occur precisely in each processing procedure of the product.
Cold rolling, calendering and annealing will produce chatter marks, roll marks, and scratches. Improper adjustment of strip grinding heads of different thicknesses or foreign matter on the pinch rollers during grinding can also cause surface quality problems.
Due to the existence of different defects on the surface of the strip, it is difficult to eliminate some defects in the grinding process or increase the number of grinding passes.
4. So customers are purchasing cold-rolled coils as substrates for grinding 8K surface or purchasing hot-rolled NO.1 entrusted cold-rolling and rolling processing. They must have sufficient thought and psychological preparation. If the 8K surface effect is not achieved, the product can be changed to a matte surface Sales.
It is not that the grinding can not reach the 8K surface effect to file a quality claim to the steel mill.
Process Result
The steel mill does not accept the complaint of the quality objection and proposes to change to frosted and other surface sales.
Suggestion
As a marketer, we must understand the needs of end customers, understand the characteristics of different stainless steel products, understand the advantages and disadvantages of stainless steel products in the processing of various processes, and through the improvement of their own business level, introduce customers clearly to the quality of the products, and then obtain customers¡¯ satisfaction. Trust and admire.