内裂纹热塑变形修复组织演变及冲击性能恢复效果

Evolution on thermal plastic deformation repair microstructure and impact performance recovery effect of internal cracks

大型锻件生产过程中会产生内裂纹等孔隙性缺陷,这类缺陷的存在具有重大安全隐患。采用高温热塑变形的方式修复低碳钢内裂纹,采用扫描电镜、金相分析等方法分析内裂纹修复区组织的演变情况,并通过标准夏比实验研究了冲击性能恢复情况。结果表明:修复过程中,仅通过一次镦粗,可以使得内裂纹完全消失,但是冲击性能只能部分恢复;通过在较高温度下的两镦一拔工艺,内裂纹完全消失的同时,冲击性能也可以完全恢复,这与内裂纹修复区晶粒分布有关。此外,经过不同的热塑变形工艺均可以在内裂纹修复区观察到Al元素和Si元素聚集。该研究结果为大型锻件内裂纹修复工艺标准的制定提供了参考依据。

Porosity defects such as internal cracks occur during the production process of heavy forgings,and the existence of such defects has major safety hazards.Therefore,the internal cracks of low-carbon steel were repaired by high temperature thermal plastic deformation,the evolution condition of microstructure in the internal crack repair area was analyzed by SEM,metallographic analysis and other methods,and the impact performance recovery condition was studied by standard Charpy experiments.The results show that in the repair process,the internal cracks disappear completely by only one upsetting,but the impact performance is only partially recavered.However,through the two upsetting and one drawing process at a higher temperature,while the internal cracks disappear completely,the impact performance is also fully recovered,which is related to the grain distribution in the internal crack repair area.In addition,after different thermal plastic deformation processes,the segregation of Al and Si elements is observed in the internal cracks repair area,and the results lay the foundation for the establishment of internal cracks repair process standard for heavy forgings.