Wear Behaviour Of Tool Steels Research Articles

Effects of pressure and counterbody hardness in the abrasive wear behavior of tool steels

Steels containing up to 1wt% of carbon and 12wt% of chromium have been used to protect the internal surface of rod mills in the cassiterite ore grinding mills. To simulate the wear behavior of this tribosystem, a test rig based on the lapping principle with counterbodies of AISI 1045 steel (160HV30) and a quenched and tempered high chromium white cast iron (751HV30) was selected. The abrasive particles were quartz sand with an average grain size of 150μm. The results showed that using carbon steel as a counterbody and a test pressure of 0.40MPa, the abrasive particles were embedded in the carbon steel leading to a sliding abrasive wear configuration. On the other hand, the use of a hard counterbody of high chromium white cast iron led to much less embedding and the rolling abrasive wear configuration prevailed. Using these parameters, no significant change in the wear rates of the studied steels could be observed. This suggests that the chromium content may be strongly reduced, and consequently the maintenance cost of this kind of mills.

The effect of coating and nitriding on the wear behaviour of tool steels

The influence of pretreatment on the wear behaviour of AISI D3 and Vanadis 4 tool steels coated with TiC, TiN and Al2O3 were experimentally investigated in air at room temperature and without lubrication. The two substrate materials were nitrided using gas nitriding. The thin films were deposited using magnetron-sputtering technique. A comparison between the wear resistance of nitrided, coated, nitrided and coated samples were made. Vickers microhardness measurements were carried out. The Al2O3 and TiN coatings out-performed TiC coatings when they were used as duplex coating in this study. The out-performance of the prenitrided Al2O3 and TiN coatings can be attributed to the presence of a nitrided subsurface.

Wear behaviour of tool steels with added (WTi)C particles

The volume fraction of hard second phase particles in tool steels is limited by the formation of large interconnected carbides on solidification that embrittle the alloy. In this work, a novel carbide master alloy, FeWTiC, which contains (WTi)C particles, was used to increase the volume fraction of carbide in an H21 hot work die steel (0.3%C, 9%W, 3%Cr). Additions of up to 5 vol.% (WTi)C were successfully made to the vacuum melted steel, producing a homogeneous distribution of (WTi)C throughout the microstructure. TEM and fracture testing confirmed that a good bond existed between the (WTi)C and martensitic matrix. Wear testing was undertaken using pure sliding against an M2 tool steel counterface, in a block on ring configuration, in the load range of 54–254 N and a sliding speed of 0.98 m/s. At 54 N, an increase in volume fraction of (WTi)C gave a reduction in wear coefficient, associated with predominantly oxidational wear, with associated ploughing of the tool steel surface by oxide particles. At higher loads the addition of (WTi)C did not result in reduced wear rates. In addition to oxidational wear, delamination occurred, frequently initiated at the matrix/M 6C particle interface. Fracture of the (WTi)C became more common as the load increased. A 1% (WTi)C marginally reduced the depth of deformation compared to the H21, but further additions had little additional effect. Detailed TEM indicated the complex interaction between oxide formation and surface deformation of the tool steel. The relationship between wear mechanism and microstructure is discussed.