Abstract
AISI M2 steel was smelted in a 150 kg medium-frequency induction furnace and cast to form round billets with a cross-section diameter of 100 mm via a vertical continuous caster and sand mold. The secondary dendrite arm spacing (λ2), cooling rates, permeability and size and distribution of grains and network carbides of the two billets were studied. The results show that the continuous casting process can effectively decrease the λ2 value, permeability and size of the grains and carbides and improve the distribution of the grains and carbides during solidification. The λ2 values of the billets cast with a sand mold and continuous caster are 37.34 μm and 21.14 μm, respectively, and the cooling rate is 3.6 K·s−1 and 12.0 K·s−1, respectively. The area fractions of carbides at the center of the billets cast with the sand mold and continuous caster are 0.24 and 0.16, respectively, and increase by 27.7% and 25.4%, respectively, compared with their average values. The average grain size of billets cast with the sand mold and continuous caster is 69.4 μm and 50.5 μm, respectively. Compared with the sand mold billet, the grain size at the center of the continuous casting billet is reduced by 25.5%. The relationship between the grain size and cooling rate is presented in this paper.
Highlights
AISI M2 steel (Fe–0.9 C–6 W–5 Mo–4 Cr–2 V, wt%) is a very popular high-speed steel because of its good combination of hardness and wear resistance at high temperatures [1,2]
Typical as-cast structure of M2 high speed steel consists of dendrites surrounded by inter-dendritic network of eutectic carbides [3]
It is well known that the mechanical properties of high speed steel strongly depend on the carbide type, shape, size and distribution, which are closely related to the as-cast structure of ingots, especially those eutectic carbides
Summary
AISI M2 steel (Fe–0.9 C–6 W–5 Mo–4 Cr–2 V, wt%) is a very popular high-speed steel because of its good combination of hardness and wear resistance at high temperatures [1,2]. M2 high speed steel manufacturing includes two steps, namely the mold casting and subsequent hot working like forging and rolling, which can break the coarse carbides network and refine structure. Typical as-cast structure of M2 high speed steel consists of dendrites surrounded by inter-dendritic network of eutectic carbides [3]. It is well known that the mechanical properties of high speed steel strongly depend on the carbide type, shape, size and distribution, which are closely related to the as-cast structure of ingots, especially those eutectic carbides. This study compares the solidification structure of M2 steel billets via a vertical continuous caster and sand mold. The quantitative relationship between the grain size and the cooling rate of the M2 steel during the solidification processes has been obtained, which has not been reported until now
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
