氮对Mn18Cr18N护环钢高温力学性能的影响

护环是汽轮发电机的重要部件。用Gleeble-1500热模拟试验机研究了成分(%)为:(1)0.53C-16.98Mn-3.17Cr,(2)0.12C-19.57Mn-19.27Cr-0.60N和(3)0.06C-18.58Mn-19.15Cr-0.69N 3种护环钢在8001 200℃的高温变形应力-应变曲线以及含N护环钢的高温塑性-断面收缩率。结果表明,随钢中氮含量的增加,动态再结晶需要的临界变形量越大,相应的变形抗力逐渐增大;含N钢在1 050℃塑性最大,高温塑性随钢中氮含量的增加而减小,因此改善变形方式以提高工艺塑性是防止热裂,提高护环质量的有效途径。

Effect of Nitrogen on Mechanical Properties of Retaining Ring Steel Mn18Cr18N at High Temperature

The retaining ring is an important component of turbogenerator. The high deformation stress-strain curves of three  kind  of  retaining  ring  steel-0.53C- 16.98Mn-3. 17Cr(1),0. 12C- 19.57Mn- 19.27Cr-0.60N(2)and  0.06C- 18.58Mn- 19. 15Cr-0.69N(3)and the high temperature plasticity- reduction of area of containing nitrogen retaining ring steel at temperature 800~1200 ℃ have been studied by Gleeble- 1500 thermal simulation machine. The results showed that with increasing nitrogen content in steel,the critical deformation value for dynamic recrystallization increased in order to gradually  increase corresponding deformation force; the maximum reduction of area of containing nitrogen steel was at 1050 ℃,and  the high plastic deformation region shrunk with increasing nitrogen content in steel. Therefore modifying deformation model to  increase process plasticity is an available way to increase the quality of retaining ring.