一种新型热作模具钢的高温磨损性能研究

Investigation on High Temperature Wear Behavior of a Newly Developed Hot-Work Tool Steel

采用球盘式高温摩擦磨损试验机,对针对某特殊工况自行研制的一种新型热作模具钢在室温、200、400、500和600℃下进行干滑动摩擦磨损试验,研究了该钢的磨损行为和磨损机制,并测试了不同温度磨损后材料亚表层的应变硬化区深度.结果表明:随着环境温度的升高,钢的磨损率呈现先升高,后降低再升高的趋势;摩擦系数随着温度增加先降低后升高;室温和200℃下磨损时其磨损机制主要为疲劳磨损;随着环境温度升高到400和500℃时,磨损表面生成一层致密氧化物并随着温度升高而增厚,呈轻微氧化磨损特征;600℃时,高温磨损表面的氧化物层继续增厚,但在试验载荷持续挤压下,氧化层出现破裂剥落,磨损率急剧升高,表现为氧化磨损;材料亚表层在磨损后产生明显的应变硬化,硬化效果随温度的升高先增强后减弱.

Dry sliding wear tests were performed at room temperature, 200, 400, 500 and 600 ℃ on a new hot-work tool steel which was developed for special condition. Wear mechanism was determined by observing and analyzing the morphology of the worn surface and subsurface. In addition, the depth of strain hardened zone below wear track and wear behavior of the new steel were evaluated. The experimental results show that the wear rate firstly increased and then decreased and finally increased with the increasing temperature. Average friction coefficient decreased at first and increased subsequently. At room temperature and 200 ℃, fatigue wear prevailed due to inadequate tribo-oxide on the worn surface. A dense of oxide layer generated on worn surface and the thickness increased as the temperature was enhanced from 400 ℃ to 500 ℃. In this case, mild oxidative wear prevailed. At 600 ℃, wear rate rapidly increased with the oxide layer fracture and spalling on worn surface under the lasted experiment load, the wear mechanism was oxidative wear. An obvious strain hardening area generated in subsurface in the process of wear and the hardening effect firstly increased and then decreased with the increase of temperature.