27 Questions 75 Answers 0 Followers
Questions related from Nikolai I. Kobasko
Powerful propellers are used in quench tanks to prevent film boiling processes and intensify cooling rate during hardening of steel. However, during batch quenching water flow inside the load...
03 March 2019 1,183 1 View
We are discussing here intensive quenching processes: IQ-2 and IQ-3 technologies. The IQ-2 technology requires the duration of transient nucleate boiling process evaluation during batch quenching....
07 July 2015 5,833 6 View
We have developed a method for optimizing chemical composition of steel to provide maximal compressive residual stresses at the surface of steel parts after intensive quenching. Depending on size...
05 May 2015 1,927 2 View
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...
04 April 2015 9,739 2 View
Critical heat flux densities are used to calculate transition from nucleate boiling to full film boiling and back from film boiling to transient nucleate boiling. To do such calculations...
04 April 2015 9,342 2 View
When bottle with water is frozen through, it cracks. The same is often happening when steel parts are quenched through. To prevent crack formation, such steel parts are quenched very slowly in...
04 April 2015 4,300 5 View
My colleagues and I have been discovered many interesting phenomena which can make a big difference when developing new technologies. However, to make a big progress, discovered phenomena must be...
03 March 2015 5,708 3 View
During the self - regulated thermal process, the surface temperature of quenched steel part maintains at the level of boiling point of a liquid and cannot be below it until boiling is finished....
03 March 2015 9,627 5 View
Cooling intensity of vegetable oil is better as compared with mineral oil since in many cases film boiling is absent. However, oxidation of vegetable oil is rather high and its cooling stability...
03 March 2015 1,274 3 View
At present, main attention is paid to alloying of steels to improve significantly their mechanical and elastic properties. As known, the ancient damascus steel was just plain carbon steel with...
02 February 2015 4,291 8 View
Alloy and high alloy steels, as a rule, are hardened in oils to decrease distortion and prevent crack formation. Since oil cools slowly, more alloy elements are added to steels in order to...
02 February 2015 8,139 6 View
As known, intensive quenching (IQ) process generates high surface compressive residual stresses which are compensated by core tensile residual stresses. If in the core of steel parts are...
01 January 2015 7,739 3 View
I'm wondering whether we can use heat transfer coefficients (HTCs) received for steady - state nucleate boiling condition to calculate temperature fields in steel parts during transient nucleate...
01 January 2015 2,375 12 View
Here is an example. A long cylindrical sample 20 mm in diameter made of AISI 52100 steel is heated to 850oC and then intensively quenched by forsed water flow. What is minimum water flow which...
01 January 2015 9,049 4 View
In the practice polymers of inverse solubility are used to substitute oils with water solutions. As a rule, concentrations are: 5%, 10%, 30%. These concentrations are not optimal.
01 January 2015 7,803 4 View
Usually, quenching of steel parts and tools are preformed in oils at the temperature 30oC - 60oC where distortion is high due to high viscosity of oils. In different surface areas of steel part...
01 January 2015 8,830 3 View
Local film boiling takes place when initial heat flux density, during immersion of heated to high temperature steel part into liquid, is equal to the first critical heat flux density qcr1. In this...
01 January 2015 4,668 3 View
Many experts say "It doesn,t make sense to calculate the time of thermal equilibrium establishing since its time is infinity" (see exponential law of cooling or heating). On the other hand, the...
01 January 2015 2,855 15 View
Real heat transfer coefficient h during nucleate boiling process means a ratio h=q/(T-Ts). Effective heat transfer coefficient is calculated as h = q/(T-Tm). Where q is heat flux density;...
12 December 2014 3,545 5 View
Grossmann factors f are used to calculate hardenability of steel depending on amount af alloys in steel. On the other hand, compressive residual stresses at the surface of steel parts depend on...
12 December 2014 5,462 1 View
Quenching under pressure in liquid media allows governing of phase transformation in steels. It can be used for creation of nano - bainitic microstructure in large steel parts due to very fast...
12 December 2014 5,112 4 View
In heat treating industry cooling curves analysis is widely used for controlling quenching processes. Special standard probes with one thermocouple at the core are used to control intensity of...
12 December 2014 4,221 3 View
In metallurgy the effective heat transfer coefficients (HTCs) of transient nucleate boiling processes are used which are ten times less as compared with the real HTCs. The original technique for...
10 October 2014 2,824 2 View
During the self- regulated thermal process, the surface temperature of quenched steel parts maintains at the level of boiling point of liquid. That can be used to monitor phase transformation in...
02 February 2014 4,570 3 View
A new method of quenching (IQ-2 process) has been developed which increases service life of steel parts by more than double. The new technology is the future of the heat treating industry. To...
01 January 2014 5,614 1 View
Transient nucleate boiling process is not enough deeply and widely investigated. Its duration is extremely important for hardening of steels and is connected with the self - regulated thermal...
01 January 2014 8,573 1 View
Prof. Tensi discovered four types of heat transfer modes (HTM) which should be taken into account when solving inverse problem (IP). Theoretically, the same cooling curve of standard probe can be...
01 January 2014 6,551 7 View
