Experimental investigation on solidification of GCr15 bearing steel by the simulated continuous casting

ABSTRACT

An experimental apparatus for simulation of continuous casting process of GCr15 bearing steel billet is established. With the apparatus, the billets of diameter 140 mm are casted in various superheats and cooling conditions. The solidification macrostructure, dendrite morphology, segregation and carbide are investigated. It is shown that melting superheats and cooling conditions remarkably influence the microstructure and solute segregation. It is found that the secondary dendrite arm spacing of the steel increases with the increase of the superheat temperature, and with decrease of the cooling rate. Lower superheat with higher cooling rate promotes the refining of the microstructure. Refining equiaxed grains structure in the centre of the billet leads to lower segregation of carbon. Furthermore, with increasing cooling rates, the spacing of the pearlite laminar is refined and the precipitation of proeutectic carbides is suppressed.

KEYWORDS:

• Bearing steel
• solidification
• dendrite morphology
• segregation
• carbide

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is financially supported by the National Natural Science Foundation of China: [Grant Number U1560202, 51604171, 51690162]; Science and Technology Commission of Shanghai Municipality: [Grant Number No.17JC1400602].