316LN不锈钢大型锻件镦粗过程中侧表面裂纹的预测

Prediction of Lateral Surface Crack for Large-sized 316LN Stainless Steel Forging During Upsetting

AP1000核电站主管道用316LN超低碳控氮奥氏体不锈钢锻造温度区间窄、变形抗力大,锻造过程中容易开裂,尤其发生在侧表面鼓肚部位。研究了316LN不锈钢大型钢锭的镦粗工艺,利用Deform-3D软件获得了锻件侧表面的最大损伤值,并将其与相应条件下的临界损伤值做了对比。结果表明,始锻温度为900℃时不会发生开裂,温度越高,可选择的工艺参数范围越小。当应变速率约为0.02 s-1时,锻件侧表面更易发生开裂。

Due to narrow forging temperature range and big resistance of deformation of 316 LN ultra-low carbon controlled nitrogen austenitic stainless steel for AP1000 nuclear power station main pipes, cracks are easily formed during the forging process, especially on the drum part at the side surface of pipe. The upsetting technology of 316 LN large stainless steel ingot was studied. The maximum damage values on the lateral surface of the forgings were obtained by using the Deform-3D software, and the maximum damage values were compared with the critical ones under corresponding conditions. The results show that cracking will not occur during the starting temperature of 900 ℃, the higher the temperature is, the smaller the process parameters can be selected. The side surface of the forgings is proner to cracking when the strain rate is 0.02 s-1.