Stamping and Cracking of Stainless Steel Sink

Quality objection case: stamping and cracking of stainless steel sink

Case Overview:

The customer used a stainless steel hot-rolled NO.1 coil from a steel mill to open the equalization process through cold rolling and calendar, and then sent it to the downstream customer to punch the flume during stamping cracking, and filed a quality objection complaint and claim to the steel plant.

Case Study:

After receiving complaints from users, the steel mill first understands the sink stamping process and the percentage of stamping cracks that occur. Generally, the stamping cracking ratio of metal materials is within the normal range of 5% under normal conditions, and the stamping cracking ratio deducts the normal loss. 30%. At the same time, the customer provides local spectral testing, which reflects the low copper content.

1. For this batch of stainless steel hot-rolled No.1 coils, the steel mill traced the origin from the steelmaking, hot-rolling, and pickling production processes, and performed process inspections at key control points in each production process, and no abnormal quality fluctuations in the production process occurred.
2. The surface hardness (HRB) of the raw materials was tested, and the average hardness (HRB) was 90.6. At the same time, the moisture content method was used to detect the composition of the sample, and the copper content and composition were controlled normally.
3. In inclusion analysis, the original board mainly contains A (sulfide) and B (alumina) inclusions, all of which are level 2, which is within the normal control range. The structure is austenite, the grain size is 6.5, and there is no carbide precipitation at the grain boundary.
4. For the various circulation links of the stainless steel hot-rolled NO.1 coil, from the analysis of the slitting, rolling, annealing, and opening process, there is no abnormal situation.
5. The cracking morphology photos of the water tank were provided by the downstream customers. From the analysis of the cracking morphology of the water tank, when the blank holder of the stamping parts is relatively rich, the water tanks are all cracked in the same place. It is recommended that customers consider mold matching and lubrication conditions is it suitable.

Process Result:

There is no quality problem with the base metal of the steel mill. It is recommended that customers adopt different forms of stamping modes and film stamping at the cracked parts, and dynamically adjust the mold degree in the hot mold state.