含铌、钛船板钢高温塑性研究

针对含铌、钛船板钢中板表面微裂纹问题，利用Gleeble-1500热应力／应变试验机模扎连铸和轧制过程，分析了温度、应变速率、析出物对已形核微裂纹的影响，结果表明：裂纹是沿晶界裂开的，裂纹的形核与晶界处杂质和析出物有很大的关系；二冷段变形对裂纹的扩展作用应引起注意；在第二脆性区，应变速率越大，钢的塑性越差，这一结果说明了轧制过程对裂纹具有不可忽视的扩展作用。

STUDYS ON HOT DUCTILITY AND PLASTICITY OF SHIP STEEL PLATE CONTAINING Nb AND Ti

In view of fine cracks occurred on the surface of the plate containing Nb and Ti for shipbuilding, the hot ductility and plasticity test was carried out on Gleeble 1500 heat stress/strain test machine. The effect of temperature, strain rate and precipitates on the initiated cracks was analyzed. The results indicate that the cracks are developed along the crystal grain boundary and its initiation is related to the inclusions and precipitates on grain boundaries. It is worth to mention that attention should be paid on the effect of slab deformation in secondary cooling zone on propagation of cracks. In the second brittle zone, the plasticity of steel is reduced with the increase of the strain rate, thus the obvious effect of rolling process on the crack propagation is observed.