Abstract:  The  effect  of cooling rate,reduction,original  austenite  grain  size  and  strain rate  of0.05C-0. 13Nb  steel  af- ter  single  pass-reduction  40%  with  2  s^-1   at   1000  ℃  or  two  pass-reduction  40%  with 2 s^-1  at   1000℃+  reduction  40%  with 5 s^-1  at 980 ℃ on structure and microhardness HV has been studied by Thermecmastor-Z thermal simulation test ma- chine.Results indicated that with increasing cooling rate the granular bainite gradually increased,of which the content was up  to93%  as  cooling  rate  was  to 5  ℃/s,and  the  HV  value  obviously  increased,while  cooling  rate  was  more  than  5  ℃/s the morphology of bainite island structure was changed and the HV value increased little; with decreasing original austenite grain size and increasing reduction the HV value decreased; but the effiect of strain rate on HV value was not appreciable.

Key words: 0.05C-0. 13 Nb , Steel, Hot , Deformation, Structure, HV , Value

摘要： 用Thermecomastor-Z热模拟试验机,研究了0.05C-0.13Nb钢单道次1000℃、2s^-1变形40%和双道次1000℃、2s^-1变形40%+980℃+5s^-1变形40%后冷却速度、变形量、原始奥氏体晶粒度和应变速率对组织和显微硬度(HV)的影响。结果表明,冷却速度增加,钢中粒状贝氏体逐渐增多,冷却速度达5℃/s时,贝氏体含量达93%,HV值显著增加;当冷却速度超过5℃/s时,贝氏体岛状组织形貌改变,HV值增加较小;随原始奥氏体晶粒尺寸减小和变形量增大,HV值减小,应变速率对HV值无显著影响。

关键词: 0．05-0．13Nb钢, 热变形, 组织, HV值