Grain Refining and Texture Control of Nonferrous Metals through High Speed Hot Rolling

研究了热轧工艺条件对Ti-6Al-4V合金、Ti-15V-3CR-3SN-3Al合金和无氧铜淬火板材组织的影响。在高速热轧Ti6Al-4V薄板时，剪切变形在表面下产生严重的剪切区。剪切应变随轧制温度的升高而增大，随轧辊表面摩擦系数的减小而减小。在α+β区轧制的钢板的严重剪切区出现了极细小的再结晶等轴晶。在1173K，3.6K的温度下，这些细小的α颗粒长大到直径为3微米。在β区轧制的钢板的严重剪切区，出现了由细小的再结晶β晶粒转变而成的极细小的针状α‘-马氏体，该组织在退火热处理后没有形成等轴组织。在剪切应变可以忽略不计的薄板中心层，形成了层状结构。…中α相的择优取向严重剪切区随轧制温度的变化而变化。在1323K(Beta区)轧制的板材中，只有(110)&lt；001&gt；取向通过Burgers关系转变的织构，这就是体心立方金属的剪切织构，称为Goss织构。在α+β区轧制的钢板的严重剪切区，织构主要由β相的剪切织构和α相的剪切织构(&lt；0001&gt；*ND)转变而成。在α+β区轧制的板材的剪切织构强度弱于在β区轧制的钢板。退火后，剪切织构强度增加，形成T织构(&lt；0001&gt；*Td)。在热轧Ti-15V-3CR-3SN-3Al薄板的过程中，剪切变形也在表面下积累，形成严重的剪切区，并出现极细小的再结晶晶带。再结晶平均晶粒度随轧制温度的降低和轧制后保温时间的延长而减小。热轧后晶粒度为3微米，冷轧后退火后晶粒长大至10微米。随着轧制温度的升高和压下量的增加，高速热轧后立即淬火的铜板组织由变形组织向再结晶组织转变。从光学显微镜和透射电子显微镜可以看出，在热轧后很短的时间内就会发生静态再结晶。较少

The effects of hot rolling condition on the structure of quenched sheet of Ti-6Al-4V alloy, Ti-15V-3Cr-3Sn-3Al alloy and oxygen free copper are investigated. In high speed hot rolling of Ti6Al-4V sheet, shear deformation produces a severely sheared region beneath the surface. The shear strain increases with increasing rolling temperature and decreases with reducing friction coefficient at the roll surface. Extremely fine recrystallized equiaxed alpha-grains appear in the severely sheared region of the sheet rolled in alpha + beta region. These fine alpha grains grows to diameter of 3mum on annealing at 1173K for 3.6ks. In the severely sheared region of the sheet rolled at beta region, extremely fine acicular alpha'-martensite transformed from fine recrystallized beta grains appears, which does not form equiaxed structure after annealing. In the central layer of the sheet where shear strain is negligibly small, lamellar structure develops. The preferred orientation of alpha phase in the … More severely sheared region changes with rolling temperature. In the sheet rolled at 1323K(beta region), only the transformed texture from (110)<001> orientation through the Burgers' relation, which is the shear texture of bcc metals known as Goss texture. In the severely sheared region of the sheet rolled in alpha + beta region, the texture consists of main components of transformed texture from shear texture of beta-phase and shear texture of alpha-phase (<0001>*ND). The intensity of the shear texture of the sheet rolled in alpha + beta region is weaker than that of the sheet rolled in beta region. After annealing, intensity of shear texture increases and T-texture(<0001>*TD) develops. In hot rolling of Ti-15V-3Cr-3Sn-3Al sheet, shear deformation also accumulates beneath the surface to form severely sheared region and a band of extremely fine recrystallized grains appears. The average grain size of recrystallized grains decreases with decreasing rolling temperature and with decreasing holding time af ter rolling. Grain size is 3mum after hot rolling and grows to 10mum on anneal ing af ter cold rolling. The microstructure of the copper sheet quenched immediately after high speed hot rolling changes from wrought grains to recrystallized grains with increasing rolling temperature and reduction. From the optical and TEM micrographs, it is concluded that static recrystallization occurs within very short interval after hot rolling. Less