Search

By placing the thermocouples inside the steel plate and measuring the actual temperature in the normalizing process, combined with the numerical calculation, the temperature variation law of different thickness steel plate is simulated and calculated. The calculation shows that the core cooling rate is the lowest at the beginning of cooling. With the decrease of temperature, the cooling rate changes and then continues to decrease. The maximum cooling rate is 0.53°C/s-0.35°C/s. When the plate surface temperature reaches 642°C-673°C, the cooling rate of steel plate surface is consistent with that of core.

With the exploitation of gas mixed with sulfur, the requirement of hydrogen induced cracking (HIC) resistance for medium carbon vessels serving at environmental with hydrogen sulfide solution become more rigorous. Through the research on HIC, the formation reasons of those are: MnS inclusions, Al2O3 inclusions, P segregation, Bainites and Macro segregation of slab. Thus if these parameters are controlled appropriately, the qualified medium carbon vessels for resistance to HIC steel will be produced. The conclusions are following: the controlled measurements to cleanliness on liquid steel, macro segregation controlled on slab, large reduction at rolling and normalizing are used to produce the HIC resistance vessels. The properties of tensile strength and low temperature impact meet the standard properly. Meanwhile there aren’t hydrogen induced cracking found in any samples.