Ni-Cr-B系高硼堆焊合金及其耐磨耐蚀性的研究

发布时间：2018-11-23 18:59

【摘要】：高硼合金以原位生成的硼化物为硬质相骨架增强耐磨性,其应用越来越广泛。很多工况对高硼合金的耐磨性和耐蚀性均有较高的要求,如注塑机的核心部件螺杆。本文设计了Ni-Cr-B-Mo和Ni-Cr-B-Fe两种Ni-Cr-B系高硼堆焊合金粉块,研究了合金元素对氩弧熔敷该合金粉块堆焊合金的组织和耐磨耐蚀性能的影响。Ni-Cr-B-Mo堆焊合金和Ni-Cr-B-Fe堆焊合金都具有快速冷却成型的定向凝固组织,与母材结合良好,存在明显的过渡区。Ni-Cr-B-Mo堆焊合金顶端为明显的过共晶组织。堆焊合金中主要硬质相为三元硼化物Mo2M'B2,其中M’为Fe、 Ni、Cr等金属元素。当B含量相同时,Mo含量为44%的堆焊合金的三元硼化物含量最少,增加或者减少Mo含量,均能增加三元硼化物的含量,且硼化物的形态差异很大。Ni-Cr-B-Mo堆焊合金中先共晶三元硼化物的显微硬度远远大于周围共晶组织。三元硼化物和共晶组织的显微硬度随Mo含量增加而减小,当Mo含量为37.53%时,先共晶三元硼化物和周围共晶组织的显微硬度最大。Ni-Cr-B-Mo堆焊合金的耐蚀性随Mo含量的增加而提高,但当Mo含量高于44.18%时,耐蚀性提高的不明显。Ni-Cr-B-Fe堆焊合金中主要硬质相为板条状和网状的具有Fe2B结构的(Fe, Cr, Ni)2(B, C)复合硼化物。随合金粉块中铁硼合金粉含量的增加,Ni-Cr-B-Fe堆焊合金中二元硼化物增加。铁硼合金粉含量为50%以上时,出现了B的衍射峰。Ni-Cr-B-Fe堆焊合金的显微硬度随着含硼量的增加而提高,但硬度提高并不明显。Ni-Cr-B-Fe堆焊合金的耐蚀性随铁硼合金粉加入量的增加而呈上升趋势。当铁硼合金粉添加量均为50%时,Ni-Cr-B-Fe堆焊合金的耐蚀性比Ni-Cr-B-Mo堆焊合金较差。当铁硼合金粉添加量均为50%时,Cr含量为5%时,硼化物主要为板条状,当Cr含量为10%时,出现了网状、蜂窝状硼化物组织。当Cr含量为15%时,硼化物呈现为相对平行,具有明显方向性的长条状。随着Cr含量的增加,高硼堆焊合金的显微硬度增大。当Cr含量为15%时,其共晶组织的显微硬度最高,长条状硼化物硬度为1252.3HV,远高于共晶组织。当Cr含量为15%时,Ni-Cr-B-Fe堆焊合金的耐蚀性最好。高硼堆焊合金的耐磨性明显优于母材Q235钢。含Mo量为37.53%的Ni-Cr-B-Mo堆焊合金的耐磨性为母材Q235的27.7倍,硼铁合金粉含量50%的Ni-Cr-B-Fe堆焊合金的耐磨性为母材Q235的15倍,耐磨性相对较差。硼铁合金粉含量的增加在一定程度上提高了堆焊合金的耐磨性,但提高并不明显。当Cr元素含量为15%时,Cr含量的增加并没有提高耐磨性,反而使其耐磨性变差。
[Abstract]:The wear resistance of high boron alloy is enhanced by in-situ formation of boride as hard phase skeleton, and its application is more and more extensive. The wear resistance and corrosion resistance of high boron alloy are required in many working conditions, such as screw, the core component of injection molding machine. In this paper, two kinds of Ni-Cr-B high boron surfacing alloy blocks of Ni-Cr-B-Mo and Ni-Cr-B-Fe are designed. The effect of alloying elements on the microstructure and wear resistance and corrosion resistance of argon arc cladding alloy was studied. Both Ni-Cr-B-Mo surfacing alloy and Ni-Cr-B-Fe surfacing alloy have directional solidification structure of rapid cooling molding. The Ni-Cr-B-Mo surfacing alloy has a hypereutectic structure at the top of the alloy. The main hard phase in surfacing alloy is ternary boride Mo2M'B2, in which M'is Fe, Ni,Cr and other metal elements. When the content of B is the same, the content of ternary boride in surfacing alloy with 44% Mo content is the least. Increasing or decreasing the content of Mo can increase the content of ternary boride. The microhardness of proeutectic ternary boride in Ni-Cr-B-Mo surfacing alloy is much higher than that in the surrounding eutectic structure. The microhardness of ternary boride and eutectic structure decreases with the increase of Mo content, when the content of Mo is 37.53, The microhardness of proeutectic ternary boride and eutectic microstructure is the greatest. The corrosion resistance of Ni-Cr-B-Mo surfacing alloy increases with the increase of Mo content, but when the Mo content is higher than 44.18, The corrosion resistance of Ni-Cr-B-Fe surfacing alloy was not improved obviously. The main hard phase in Ni-Cr-B-Fe surfacing alloy was (Fe, Cr, Ni) _ 2 (B, C) boride with Fe2B structure. With the increase of Fe-B alloy powder content in alloy block, the binary boride in Ni-Cr-B-Fe surfacing alloy increases. When the content of Fe-B alloy powder is more than 50%, the diffraction peak of B appears. The microhardness of Ni-Cr-B-Fe surfacing alloy increases with the increase of boron content. The corrosion resistance of Ni-Cr-B-Fe surfacing alloy increases with the increase of Fe / B alloy powder content. When the content of Fe-B alloy powder is 50%, the corrosion resistance of Ni-Cr-B-Fe surfacing alloy is worse than that of Ni-Cr-B-Mo surfacing alloy. When the addition amount of Fe-B alloy powder is 50 and the content of Cr is 5, the boride is mainly plate-like, and when the content of Cr is 10, there is reticular and honeycomb boride structure. When the content of Cr is 15, the boride presents a stripe of relative parallelism and obvious directionality. The microhardness of high boron surfacing alloy increases with the increase of Cr content. When the content of Cr is 15, the microhardness of eutectic structure is the highest, and the hardness of long boride is 1252.3 HV.This is much higher than that of eutectic structure. When the content of Cr is 15, the corrosion resistance of Ni-Cr-B-Fe surfacing alloy is the best. The wear resistance of high boron surfacing alloy is better than that of Q235 steel. The wear resistance of Ni-Cr-B-Mo surfacing alloy containing 37.53% Mo is 27.7 times of that of Q235, and that of Ni-Cr-B-Fe surfacing alloy containing 50% boron ferroalloy powder is 15 times of that of Q235. The wear resistance of Ni-Cr-B-Fe surfacing alloy containing 37.53% Mo is relatively poor. The increase of boron ferroalloy powder content improves the wear resistance of surfacing alloy to some extent, but the increase is not obvious. When the content of Cr is 15, the increase of Cr content does not improve the wear resistance, but makes the wear resistance worse.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG42

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