【摘要】 研究了电子束快速成形TC18钛合金(简称KTC18)3种典型退火制度下显微组织演化规律及与显微硬度的关系。结果表明,在700~830oC单一退火条件下,合金相组成为初生α相与亚稳β相,随着温度升高,初生α相体积分数减少,基体显微硬度变化较小;在双重退火条件下,500~650oC之间低温退火过程中会析出细小、编织排列的条状α相,可显著提高基体硬度,随着低温退火温度升高,α析出相粗化且数量变少,导致基体硬度降低;三重退火条件下,高温炉冷和中温退火过程中会产生粗大的竹叶状一次α相,其数量随中温退火温度升高而减少,对显微硬度影响较小。低温退火析出的细小、弥散α相对KTC18显微硬度影响最大,其数量和尺寸取决于其他类型α相的数量和低温退火制度。更多还原

【Abstract】 Microstructure and micro-hardness of TC18 titanium alloy based on electron beam rapid forming under three kinds of typical heat treatments are studied. The results show that, under single heat treatment condition, the alloy is composed of primary α phase and metastable β phase. With increasing of temperature volume fraction of primary α phase decreases and no obvious variation on micro-hardness is found. Under double heat-treatment conditions, fi ne α phase occurs during low temperature annealing at 500–650oC and can increase micro-hardness significantly, however, with increasing of temperature, fine α phase becomes coarsened and its length-width ratio decreases, which results in decreasing of micro-hardness. Under triple heat-treatment conditions coarse bamboo-leaf-like α phase occurs during furnacecooling and medium-temperature annealing stage. Bamboo-leaf-like α phase in the present article has a relativelysmall effect on micro-hardness. Fine α phase during low temperature annealing affects micro-hardness most and its amount and size depend on amount of other type coarse α phases and low-temperature annealing conditions.更多还原