Molybdenum Rolling Direction and Deformation Percentage

-Impacts on Quality and Performance of Molybdenum Sheets

Molybdenum Rolling Direction in Sheet Processing

Molybdenum rolling into sheets involves a complex, exacting, multi-stage process with numerous variables. Among the most critical variables are rolling direction and deformation, which largely contribute to the finished product’s quality and performance.

In the initial stages, inherently porous molybdenum plates are deformed to stimulate particle movement, solidify structure, fill pores, and eliminate internal flaws. These changes enhance the slab’s density and transform it from a loosely structured, sintered state into a cohesive form. Concurrently, the choice of unidirectional or cross rolling also greatly influences the slab’s structural uniformity, defect formation, and crack propagation.

Control and Effect of Deformation in the Rolling Process

Successful molybdenum rolling requires carefully calibrated deformation during the initial rolling phase to ensure the correct application of rolling force onto the slab. Insufficient deformation may produce unevenness, leading to defects, including mouth opening; delamination; and edge cracking, during subsequent processing stages. In turn, the final product may exhibit unfavorable surface features, including burrs; peeling; and decreased overall yield rate. Moreover, each subsequent rolling pass must avoid excessive deformation. The gradual reduction in deformation with successive hot, warm, and cold rolling stages must adhere to strict percentages to prevent the instigation of microscopic cracks that could lead to fractures.

Effects of Unidirectional vs. Cross Rolling

Molybdenum rolling direction influences the properties of the resultant processed sheets.

Unidirectional rolling produces a fibrous texture with varying properties based on measurement direction.

In comparison, cross-rolled sheets feature a more uniform grain distribution due to an overlapping grain structure. This difference makes cross-rolling a more effective method for reducing defect formation.

Cross rolling is more effective in minimizing anisotropy and crack expansion, producing uniform mechanical properties in all directions. This method, however, requires maintaining consistent deformation levels when altering the rolling direction to ensure structural uniformity.