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在1×10-3／s应变速率下对含Nb钢连铸坯试样的高温延塑性进行了测定.在温度降至1100℃以下的变形试样中Nb（C，N）开始由γ晶中析出，1000-950℃之间析出的Nb（C，N）较粗大并在钢中零散分布;温度降至900℃左右时，大量微细的Nb（C，N）在γ晶界和晶粒内析出，尺寸平均为5-8nm，间距在30nm左右，造成了γ相区低温域合Nb钢延塑性的急剧减少;温度降至800℃时，先共折铁素体开始在γ晶界析出，钢的延塑性继续降低.由于含Nb钢试样共折转变的推迟，与不含Nb钢相比，其第Ⅲ脆性温度域向低温延伸.
The high temperature ductility of the Nb-containing steel slab samples was measured at a strain rate of 1 × 10-3 / s. The Nb (C, N) , The precipitated Nb (C, N) is coarser and dispersed in steel at 1000-950 ℃. When the temperature is reduced to about 900 ℃, a large amount of Nb (C, N) Within a mean size of 5-8nm, a pitch of about 30nm, resulting in a sharp reduction of the ductility of the Nb steel in the low temperature region of the γ phase; when the temperature is lowered to 800 ° C, the first commonfold ferrite begins to precipitate at the γ grain boundary , The ductility of the steel continues to decrease.Because of the postponed transformation of Nb-containing steel samples, the third brittle temperature region extends to the low temperature compared with the Nb-free steel.