Cr-Ni-Mn-Mo-V系耐磨钢的韧性与韧化研究

【作者】 张劲松；

【导师】 袁子洲； 李士燕；

【作者基本信息】 兰州理工大学 ， 材料学材料的强韧化， 2003， 硕士

【摘要】 本文通过对Cr-Ni-Mn-Mo-V系合金耐磨钢性能和强韧化的研究，确定了该材料的常规热处理工艺，并测定了该工艺下材料的力学性能，通过研究发现该类材料性能优异，能够满足中、低冲击载荷下磨损的工况要求。为了能够将该类材料更好地运用到实际生产中，按照实际工厂可行的热处理工艺处理了一批用该类材料铸造的锤头，并对其进行了不同工艺的深冷处理。 通过对锤头材料的深冷处理发现，深冷处理可以较大幅度地提高材料的冲击韧性，略微提高材料的硬度，在不同的深冷处理工艺中，多次短时深冷处理效果最好，冲击韧性可以提高一倍以上，经过深冷处理后的材料能够满足中、低冲击载荷下磨损的要求。深冷处理前后的材料在MLS-23型湿砂橡胶轮式磨损试验机进行磨粒磨损试验，正压力为170牛顿，发现材料的磨损形式主是微观犁削，磨损形貌是滑痕和犁沟，没有出现塑性变形和剥落的现象，在磨损面的亚表层没有发现白层，说明材料的韧性较好，在该磨损条件下为正常的犁削磨损，影响材料耐磨性的主要因素是材料的硬度。 对深冷处理前后的材料进行X衍射分析，发现深冷处理后材料中的残余奥氏体数量减少，部分转变为细小的马氏体，马氏体的轴比(c／a)有所降低。推断有碳化物从马氏体中析出，并呈弥散分布，马氏体品粒变细。多次短时深冷处理后残马氏体轴比降低最多，马氏体含碳量下降最多，说明有更多的碳从马氏体中析出，马氏体韧性提高最多，但由于析出的碳化物数量有限，不能从X衍射图中得到碳化物的衍射峰。分析认为马氏体含碳量的降低和弥散分布的微细碳化物对裂纹的阻碍是材料韧性提高的主要原因，少量残余奥氏体转变为马氏体是材料硬度提高的主要原因。更多还原

【Abstract】 The properties and strengthening of Cr-Ni-Mn-Mo-V wear steel was researched in this article. The appropriate heat treatment of them was working-out and the mechanics performances were measured, and find the materials can be used in abrasive wear on medium and low impulsion-load. In order to heat-treat them in the factory, the hammerhead of this materials were heat-treat according to actual condition of common factory, then they were treated in different processes in fluid nitrogen.After cryogenic treatment of those hammerhead, we can find their hardness improved appreciably but the impact toughness improved obviously. In all the processes, times without number and short time is the best process and the impact toughness can be doubled after treat go by the process. We test these materials on MLS-23 wet-sand-rubber-wheel wear machine and find when the pressure is 120N, the form of wearing is furrow and there is no piece flaked away and no distortion on the wearing surface. It show that in this condition the materials toughness is enough which make the wearing form was furrow and wearing was decided by the hardness of the materials.The X-ray diffraction can be used to analysis the variation of the change of the materials after cryogenic treatment. The data shows that the partial quantity of retained austensite is declined and change to martensite after cryogenic treatment, the ratio of c/a is declined at the same time there has some carbide particles precipitate in martensite. The treatment process of times without number and short time is the most obvious. We draw the conclusion that it is the carbon of martensite decreasing and the precipitation of carbide particles block the flaws enhance the toughness of the materials, and the changing of some retained austensite to martensite induce to the hardness improvement.更多还原