The bainitic nano - structure was obtained for alloy steel containing 0.98C; 1.46Si; 1.89 Mn; 1.26 Cr; 0.09 V (see www.msm.cam.ac.uk/phase-trans). I'm wandering whether is it possible of obtaining such nano - structure for plain carbon steel or very low alloy steel?
One can use laws of transient nucleate boiling process which takes place when quenching in cold liquid. During transient nucleate boiling process, surface temperature of steel part maintains at the level of boiling point of a liquid and cannot be below it until boiling is finished. After boiling is finished, steel part goes immediately for tempering at 200oC to prevent martensitic transformation and provide bainitic transformation at 200oC. However, It can be done for high carbon steel with Ms = 120oC. When Ms, for example, is 200oC, quenching under pressure will perfectly work. Also,water salt solutions of high concentration can be used which should be carefully investigated and prepared for this purpose. What do you think about it?
A high concentration of water salt solution (CaCl2 + Ca(OH)2) was proposed as a quenchant to increase its boiling point up to 170oC. Small amount of Ca(OH)2 was added to solution to maintain its pH at the level 8 - 12 that decreases corrosion. The prepared solution was used to fulfill bainitic transformation at low temperature and prevent martensitic transformation in steels with martensite start temperature Ms below 170oC. Disadvantage of such solution is corrosion which cannot be eliminated completely. I believe that organic salt solutions can be developed which completely prevent corrosion and have boiling point up to 200oC. Such solutions create excellent condition for obtaining bainitic nano - structure in high carbon and low alloy steels.
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