Toughness And Toughening Of Cr-ni-mn-mo-v System Wear-resistant Steel

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.