Thermomechanical Wear Testing of Metal Matrix Composite Cladding for Potential Application in Hot Rolling Mills

Abstract

Laser metal deposition (LMD) is utilized to clad the surface of a miniaturized test roll (Ø 40 mm) of tool steel. The cladding consists of two layers: a nickel alloy as intermediate layer deposited onto the surface of the steel substrate, and a metal matrix composite (MMC) as top layer consisting of spherical tungsten carbide particles embedded into the nickel alloy matrix. The thermomechanical wear behavior of the cladding is investigated on a test rig, where the test roll is pressed against an inductively heated load roll. Multiple test runs up to several hours simulating industrial loading conditions are performed. The presented testing procedure enables predicting the time-dependent abrasive wear behavior of the cladding, in particular for hot rolling mill applications. After testing for 8 h at temperature of 650 C and at contact pressure of approximately 1 GPa, the maximum depth of the wear mark is about 0.12 mm. Partial cracking, debonding and dissolution of the tungsten carbide particles, as well as formation of iron and chromium oxides at the surface of the wear marks occur. However, as low abrasive wear is observed, the investigated MMC may potentially be applicable for cladding rolls in steel hot rolling mills.

Microstructural and Thermal Characterization of 316L + WC Composite Coatings Obtained by Laser Cladding

“…This corresponds to the solidification of large crystals of γ‐WC 1– x carbide, forming a carbide crown around the partially dissolved WC particles (Figure 1b). [ 1 ] The remaining WC cores act as heterogeneous nucleation sites. [ 15,32 ] The enlarged shape of the H10 peak on the DTA curve (Figure 4) can be associated with the partially dissolved WC cores that transformed completely to γ‐WC 1– x (Figure 5) at the end of the DTA thermal cycle.…”

“…To improve on this weakness, metal matrix composite (MMC) coatings could be applied by LC. [1,2,4] Tungsten carbide (WC) is a common reinforcement in Ni-based alloys for applications above 600 C and in Fe-based alloys for applications up to 400 C. [1,3,5,6] WC is considered a good ceramic reinforcement due to its high melting point and good wettability with both alloys. [6] Moreover, WC can retain its room temperature hardness up to 1400 C. Its dissolution by interfacial reactions with the molten metal during casting is a well-known challenge in the production of metal matrix composites.…”

“…[5,8,9] Previous studies on WC-reinforced composites have focused on feasibility issues, [4,10] on the influence of the feedstock [5,8] and the mechanical properties. [1][2][3] However, there are very few studies focusing on the nature of the carbides formed in the microstructure of those composites, when the solidification is achieved at extremely high cooling rates. The main difficulties are found in the identification and the differentiation of those new mixed carbides.…”

“…LC involves ultrafast cooling rates during the solidification stage and subsequent solid‐state transformations with limited diffusional phenomena, thus giving rise to out‐of‐equilibrium phases. [ 1–3 ]…”

“…LC involves ultrafast cooling rates during the solidification stage and subsequent solid-state transformations with limited diffusional phenomena, thus giving rise to out-of-equilibrium phases. [1][2][3] Stainless steel (SS) 316L is a workhorse material due to its excellent corrosion resistance and good mechanical properties, but it exhibits a relatively weak wear resistance. To improve on this weakness, metal matrix composite (MMC) coatings could be applied by LC.…”