After the launch of Baosteel Desheng’s new production line, the 400-series stainless steel production-sales-research team began leading the trial manufacturing of martensitic stainless steel products. During the initial production phase, the trial-manufactured 30Cr13 product exhibited “water ripple” defects when used by slant-grind knife users, showing bright white streaks on the blades. This could not meet the requirements of high-end slant-grind knife users. The “water ripple” defect severely impacted the market expansion and sales growth of the 30Cr13 product. In response, the company established a special team to address the “water ripple” defect, building on the foundation of the 400-series production-sales-research team.
**Analyzing the Micro-Mechanism of the Water Ripple Defect:**
The task force first conducted a systematic analysis of the water ripple defects in the 30Cr13 slant-grind knives. Through metallographic and electron microscope analysis, it was determined that the water ripple was caused by the segregation and aggregation of large primary carbide particles. Combined with phase diagram analysis and slab structure dissection, the team speculated that the water ripple was related to the formation of bright white bands during electromagnetic stirring in the continuous casting process, with the key issue being the resolution of segregation in the continuous casting slabs.
**Analyzing the Relationship Between Early Continuous Casting Process and Bright White Bands:**
The continuous casting process impacts slab segregation, which ultimately affects the water ripple defect in the finished product. Due to the unique characteristics of the new production line’s continuous casting equipment, the team could not simply replicate the processes of other manufacturers. Specifically, differences in electromagnetic stirring equipment, installation positions, and process parameters required practical experiments to determine the optimum parameters. By drawing on the continuous casting process characteristics of Shanghai Stainless Steel and Taiyuan Stainless Steel, and applying the basic principles of segregation control in continuous casting, the team developed several trial plans. Through experimental comparison, they identified the segregation influence of the bright white bands and established the optimal range of process parameters.
**Determining the Final Production Plan and Successful Implementation:**
Based on the results of early production trials and on-site observations, the team initially designed three production plans. At the final plan review meeting, the task force finalized the implementation details and specific measures based on the on-site situation. After thorough production process preparations, four furnaces, yielding approximately 520 tons of finished products, were successfully produced on July 8. Hot rolling was completed on July 9, and pickling coils were produced on July 20.
Dr. Dong Wenbu, the head of the task force, conducted a laboratory trial grind on the pickling coil samples, and no water ripple defects were found in the three trial knives. Based on this, the task force sent 12 sample plates to slant-grind knife users for trial production. At present, all samples have undergone slant-grind testing, with feedback indicating no water ripple defects. Additionally, users placed follow-up orders for 30Cr13 products.
The effective push by the 400-series production-sales-research team and the water ripple defect task force reduced the occurrence of slant-grind knife water ripple defects from nearly 100% in the initial trial production to 0%. This laid a solid foundation for the production increase and market expansion of the 30Cr13 product on the new production line, significantly enhancing the company’s competitiveness in martensitic steel products.