三辊轧制镁合金薄壁管成形工艺及微观组织

为了制备高质量的镁合金薄壁管材,利用三辊轧管机研究了冷轧镁合金薄壁细管的成形工艺.分析了轧制时管材易出现开裂的原因,发现其与变形量和中间退火工艺有关.结果表明,当主变形的当量变形ε_H& lt; 0.2时,可以得到质量和性能都符合要求的管材; 当主变形的当量变形ε_H& gt; 0.3时,管材表面成形性较差,且易出现表面裂纹.退火温度为300 ℃,保温时间为90 min,然后再进行空冷的中间退火工艺可以实现晶粒细化,得到的平均晶粒尺寸约为9.8 μm,从而提高了管材进行进一步轧制的变形能力.

Forming process and microstructure of three roller rolled magnesium alloy thin wall pipe

In order to prepare the magnesium alloy thin-wall pipe with high quality, the forming technology for cold rolled magnesium alloy thin-wall pipe was studied with a three-roller pipe rolling mill. The reasons for the easy cracking of the pipe during cold rolling process were analyzed. It is found out that the cracking is related to both deformation amount and intermediate annealing process. The results show that when the equivalent deformation of main deformation(ε_H)is less than 0.2, the pipe with quality and properties to satisfy with the requirements can be attained. When the equivalent deformation of main deformation is over 0.3, the surface formability of the pipe is poorer, and the surface cracks are easy to appear. In addition, the intermediate annealing process with the annealing temperature of 300 ℃ and holding time of 90 min plus air cold can realize the grain refinement, and the obtained average grain size is 9.8 μm. Therefore, the deformation ability for further rolling of the pipe is improved.