坯料圆角对不锈钢挤压管外表面的影响

Influence of billet fillet on outside surface of extrusion stainless tube

以316L不锈钢-Φ360 mm系列、Φ219 mm×11 mm挤压规格为例,通过扩孔模型(分为坯料圆角在上和圆角在下)和挤压模型(坯料前端有圆角和无圆角)建模,采用有限元法对比分析了坯料圆角对挤压不锈钢管外表面裂纹缺陷的影响。结果说明,圆角在下扩孔后圆角消失,但圆角在上扩孔后圆角仍保留;坯料前端有圆角有利于挤压管前端外表面质量,但坯料前端无圆角不利于挤压管前端外表面质量,挤压过程中产生的应力集中点易成为裂纹源。对坯料圆角进行了优化设计并对挤压生产线进行了调整,最终解决挤压管前端外表面裂纹缺陷。

Taking Φ360 mm series and Φ219 mm × 11 mm extrusion specifications of 316 L stainless steel as an example,finite element（ FE） method was used to analyze the effect of the billet fillet on crack defects at outer surface of extruded stainless tube by expanding modeling（ including billet fillet at top and bottom） and extrusion modeling（ with and without fillet at the front end of billet）. The results show that the fillet disappears after expanding process when fillet at bottom of billet,but the fillet still retains after expanding process when fillet at top of billet. The billet with fillet at the front end is favorable to the quality of outside surface of the extrusion tube,but the result is opposite when billet without fillet at the front end and the stress concentration point generated during the extrusion process is easy to be the crack source. The billet fillet was designed optimally and the extrusion production line was also adjusted,then the crack defects at outer surface of the front end of stainless extrusion tube were solved eventually.