高硼铁基合金在不同铸型中凝固的组织与力学性能

高硼铁基合金在熔模壳型和金属铸型中凝固时,铸态组织都是由树枝状基体和共晶硼化物Fe2B组成.随熔体冷却速率增加,枝晶晶粒尺寸减小,硼化物形态从熔模壳型时的鱼骨状变为金属铸型时的筛网状,硼化物在组织中分布的均匀性增加,但其化学组成没有改变.经1030℃保温2 h,水淬以及200℃回火1 h后,两种铸型铸造试样的基体大部分转变为板条状马氏体;熔模壳型铸造试样的硼化物形态基本保持不变,而金属铸型铸造试样的硼化物粒化.热处理后,金属铸型铸造试样的力学性能高于熔模壳型铸造的试样,其硬度提高5.9%,抗拉强度提高17.5%,冲击韧度提高60%.

Effect of Solidification Condition on Structure and Properties of High Boron Iron-Base Alloy

High boron iron-base alloy is a new kind of wear-resistant material, which takes borides as wear-resistant phases. In structure, matrixes and borides were included in as-cast condition and the matrixes were changed with different alloying elements and quantity. Borides were distributed in the shape of continuous net in the structure of high boron iron-base alloy. When the melt was solidified in metal mould and sand mould respectively, the grain size of austenitic primary crystal decreases with the cooling rate increase. In addition, the morphology of borides was changed greatly. After heat treatment, borides of samples made of sand mould were changed little, otherwise, borides of samples made of metal mould were changed to granulation shape and the impact toughness was increased by 60%..