The influences of deformation degrees on the microstructure evolution of GCr15 steel in cold ring rolling and following heat treatment (quenching and temper) are investigated in this paper. As the deformation is uneven, microstructure at the outer surface, middle place and inner surface on the cross-section of the ring is selected for the study. The microstructure is characterised by scanning electron microscopy, optical microscopy and X-ray diffraction. The transformation is studied with differential scanning calorimetry, and the hardness is examined by Vickers hardness tester. The results show that the deformation is severe on the outer surface but slight on the middle place and inner surface. A large degree of deformation leads to the acceleration of carbide dissolution, the grain refinement and the increase of hardness. In addition, the deformation results in the decrease of transformation temperature according to the differential scanning calorimetry data.
WalkerP. F. F.: ‘Improving the reliability of highly loaded rolling bearings: the effect of upstream processing on inclusions’, Mater. Sci. Technol., 2014, 30, 385–410. doi: 10.1179/1743284713Y.0000000491
HuaL. and ZhiZ. Z.: ‘The extremum parameters in ring rolling’, J. Mater. Process. Technol., 1997, 69, 273–276. doi: 10.1016/S0924-0136(97)00029-0
4.
QianD. S., HuaL. and ZuoZ. J.: ‘Investigation of distribution of plastic zone in the process of plastic penetration’, J. Mater. Process. Technol., 2007, 187–188, 734–737. doi: 10.1016/j.jmatprotec.2006.11.039
5.
YanF. L., HuaL. and WuY. Q.: ‘Planning feed speed in cold ring rolling’, Int. J. Machine Tools Manuf., 2007, 47, 1695–1701. doi:10.1016/j.ijmachtools.2007.01.009
6.
UtsunomiyaH., SaitoY., ShinodaT. and TakasuI.: ‘Elastic–plastic finite element analysis of cold ring rolling process’, J. Mater. Process. Technol., 2002, 125–126, 613–618. doi: 10.1016/S0924-0136(02)00354-0
7.
YeaY., KoY., KimN. and LeeJ.: ‘Prediction of spread, pressure distribution and roll force in ring rolling process using rigid–plastic finite element method’, J. Mater. Process. Technol., 2003, 140, 478–486. doi: 10.1016/S0924-0136(03)00721-0
8.
HanX., HuaL., ZhouG. H., LuB. H. and WangX.: ‘A new cylindrical ring rolling technology for manufacturing thin-walled cylindrical ring’, Int. J. Mech. Sci., 2014, 81, (4), 95–108. doi: 10.1016/j.ijmecsci.2014.01.018
9.
HanX. and HuaL.: ‘Plastic deformation behaviors and mechanical properties of rolled rings of 20CrMnTi alloy in combined radial and axial ring rolling’, Mater. Design, 2014, 58, (6), 508–517. doi: 10.1016/j.matdes.2014.01.072
10.
YangH., GuoL. G. and ZhanM.: ‘Role of friction in cold ring rolling’, J. Mater. Sci. Technol., 2005, 21, 914–920. doi: 10.1179/174328405X71639
11.
GuoL. G. and YangH.: ‘Effect of sizes of forming rolls on cold ring rolling by 3D-FE numerical simulation’, Trans. Nonferrous Met. SOC. China, 2006, 16, 645–65l. doi: 10.1016/S1003-6326(06)60270-7
12.
YangH., GuoL. G., ZhanM. and SunZ. C.: ‘Research on the influence of material properties on cold ring rolling processes by 3D-FE numerical simulation’, J. Mater. Process. Technol., 2006, 177, 634–638. doi: 10.1016/j.jmatprotec.2006.03.209
13.
QianD. S. and HuaL.: ‘Blank design optimisation for T-section profile ring rolling’, Ironmak. Steelmak., 2009, 36, 462–469.
14.
RyttbergK., WedelM. K., RecinaV., DahlmanP. and NyborgL.: ‘The effect of cold ring rolling on the evolution of microstructure and texture in 100Cr6 steel’, Mater. Sci. Eng. A, 2010, 527, 2431–2436. doi: 10.1016/j.msea.2009.12.016
15.
LiH. W., FengL. and YangH.: ‘Deformation mechanism of cold ring rolling in view of texture evolution predicted by a newly proposed polycrystal plasticity model’, Trans. Nonferrous Met. Soc. China, 2013, 23, 3729–3738. doi: 10.1016/S1003-6326(13)62923-4
16.
EppJ., SurmH., HirschT. and HoffmannF.: ‘Residual stress relaxation during heating of bearing rings produced in two different manufacturing chains’, J. Mater. Process. Technol., 2011, 211, 637–643. doi: 10.1016/j.jmatprotec.2010.11.022
17.
WuM., HuaL., ShaoY. C. and ZhouQ. J.: ‘Influence of the annealing cooling rate on the microstructure evolution and deformation behaviours in the cold ring rolling of medium steel’, Mater. Design, 2011, 32, 2292–2300. doi: 10.1016/j.matdes.2010.11.007
18.
WeiW. T. and WuM.: ‘Effect of annealing cooling rate on microstructure and mechanical property of 100Cr6 steel ring manufactured by cold ring rolling process’, J. Cent. South Univ., 2014, 21, 14–19. doi:10.1007/s11771-014-1909-4
19.
RashadM. M. and BaioumyH. M.: ‘Effect of thermal treatment on the crystal structure and morphology of zirconia nanopowders produced by three different routes’, J. Mater. Process. Technol., 2008, 195, 178–185. doi: 10.1016/j.jmatprotec.2007.04.135
20.
BeswickJ.: ‘Effect of prior cold work on the martensite transformation in SAE 52100’, Metall. Trans. A, 1984, 15A, 299–306. doi: 10.1007/BF02645115
21.
FurukawaM., IwahashiY., HoritaZ., NemotoM., TsenevN. K., ValievR. Z. and LangdonT. G.: ‘Structural evolution and the Hall-Petch relationship in an Al–Mg–Li–Zr alloy with ultra-fine grain size’, Acta Mater., 1997, 45, 4751–4757. doi: 10.1016/S1359-6454(97)00120-1
transformation is studied with differential scanning calorimetry, and the hardness is examined by Vickers hardness tester. The results show that the deformation is severe on the outer surface but slight on the middle place and inner surface. A large degree of deformation leads to the acceleration of carbide dissolution, the grain refinement and the increase of hardness. In addition, the deformation results in the decrease of 
transformation temperature according to the differential scanning calorimetry data.