Effects of process parameters on fragment and refinement of millimeter- grade coarse grains for 316LN steel during hot cogging  

作　　者：Da-shan Sui Hai-ming Zhang Hong-yang Zhu Zhe Zhu Zhen-shan Cui 

机构地区：[1]National Die & Mold CAD Engineering Research Center, Shanghai Jiao Tong University, Shanghai 200030, China [2]Shanghai Heavy Machinery Plant, Shanghai 200245, China

出　　处：《Journal of Iron and Steel Research International》2017年第5期529-535,共7页

基　　金：financially sponsored by National Natural Science Foundation of China(Grant No.51675335);the support from Shanghai Rising-Star Program(Grant No.17YF1408900);the Young Scientist Research Award from Shanghai Jiao Tong University(Grant No.16X100040025)

摘　　要：The heterogeneous mixed-grain microstructure is a common defect for the heavy forging of 316LN austenitie stainless steel. Isothermal compression experiments were performed on a Gleeble-3500 thermo-mechanical simulator to investigate the effect of process parameters on the fragment and re- finement of millimeter-grade coarse grains （MCGs） during hot cogging. The experimental results in- dicate that the stress of MCG specimens is much larger than that of fine grain （FG） ones at 1150 ℃, while the stress difference between MCG and FG samples became smaller at 1200 ℃. Moreover, the MCGs can be well fragmented and refined under the condition of temperature of 1200 ℃, strain rate of 0.01 s-1 , and reduction rate of 50%. Meanwhile, numerical simulations were conducted to study the influences of temperature, strain and strain rate on microstructure evolution. The results of ex- periments and simulations comprehensively demonstrate that the MCG results in the increase of de- formation resistance and incompatibility of deformation, and it can be fragmented and refined at 1200 ℃ so that the plastic deformation energy decreases remarkably with the increase of temperature from 1 150 to 1200 ℃.The heterogeneous mixed-grain microstructure is a common defect for the heavy forging of 316LN austenitie stainless steel. Isothermal compression experiments were performed on a Gleeble-3500 thermo-mechanical simulator to investigate the effect of process parameters on the fragment and re- finement of millimeter-grade coarse grains （MCGs） during hot cogging. The experimental results in- dicate that the stress of MCG specimens is much larger than that of fine grain （FG） ones at 1150 ℃, while the stress difference between MCG and FG samples became smaller at 1200 ℃. Moreover, the MCGs can be well fragmented and refined under the condition of temperature of 1200 ℃, strain rate of 0.01 s-1 , and reduction rate of 50%. Meanwhile, numerical simulations were conducted to study the influences of temperature, strain and strain rate on microstructure evolution. The results of ex- periments and simulations comprehensively demonstrate that the MCG results in the increase of de- formation resistance and incompatibility of deformation, and it can be fragmented and refined at 1200 ℃ so that the plastic deformation energy decreases remarkably with the increase of temperature from 1 150 to 1200 ℃.

关 键 词：316LN steel Hot deformation Coarse grain Microstrueture evolution Numerical simulation 

分 类 号：TG316[金属学及工艺—金属压力加工] TG142.1[一般工业技术—材料科学与工程]