Cylinder series test, Mechanical Engineering

Assignment Help:

Cylinder Series Test

A series of round bars of various diameters are austenitized and quenched into oil or water. The bars are long sufficient hence the cooling of section at the middle of the length is not affected via the ends. After hardening every bar is cut in half and hardness measured on different points along a diameter. The graph in between distance and hardness from the centre is then prepared as in following figure. From such graph the diameter at that 50% of the structure is martensite is calculated. While such graph the diameter is plotted against bar diameter, this becomes possible to find out the bar diameter whether 50% martensite would form at the centre. This is termed as critical diameter for such quenching medium. Because the rate of cooling is less for oil quench after that for water quench, the critical diameter, of any type of steel will be less for oil quenching than for two water quenching. Quench severity is an index in which quantitatively explains the quenching situation. Such index indicated by H is explains as given ratio.

H = Heat transfer coefficient between steel and fluid/Thermal conductivity of steel

1409_Cylinder Series Test.png

Figure: Variation of Hardness along with Depth in Water-quenched Cylindrical Bars of (a) Plain Carbon Steel, (b) 1% Cr-V Alloy Steel

Obviously, when H → ¥, it shows the severest condition of quench, sense that surface of steel instantly reaches the quenching medium temperature. The critical diameter for that, an unrealizable and ideal situation is termed as ideal critical diameter. For infinite H-value ideal critical diameter and the critical diameter will be similar. For other H values the critical diameter will be slighter. Given figure illustrates the relationship in between ideal diameters and critical diameters for various H-values. Table no.10 illustrates relative values of H such can be acquired in different quench media beneath various condition along with value of one for still water as base.

1739_Cylinder Series Test1.png

Figure: Relation between Critical Diameter, Ideal Critical Diameter and Severity of Quench

Table no: Relative Quench Severities

Agitation of Quenching Medium

Movement of

Pieces

Severity of Quench

Air

Oil

Water

Brine

None

None

0.02

0.3

1.0

2.2

None

Moderate

-

0.4 - 0.6

1.5 - 3.0

-

None

Violent

-

0.6 - 0.8

3.0 - 6.0

7.5

Violentor spray

-

-

1.0 - 1.7

6.0 - 12.0

-


Related Discussions:- Cylinder series test

Evaluate the temperature gradient in the flow direction, A plane wall (ther...

A plane wall (thermal conductivity = 10.2 w/m o c) of 100 mm thickness and area 3m 2 has steady surface temperature of 170 o c and 100 o c. Evaluate :- (i) The temperature

Show pneumatic test, Q. Show Pneumatic Test? Pneumatic testing presents...

Q. Show Pneumatic Test? Pneumatic testing presents hazards that must be addressed as part of the engineering design of the pressure vessel. Due to the additional hazards of

Hazardous areas classification, Hazardous Areas are formally ranked as bein...

Hazardous Areas are formally ranked as being a designated hazardous area using the relevant regional or country standards that are directly applicable to the plant design under con

Tom, velocity ratio is 3 .pinion has 40 teeth. what would be the gear no of...

velocity ratio is 3 .pinion has 40 teeth. what would be the gear no of teeth?

BEEE, What is alternating quantity?

What is alternating quantity?

Dust collector, Dust Collector:             Dust collector system is to...

Dust Collector:             Dust collector system is to collect the blast burrs or waste particle created during the blasting process. During the blasting process, this dust co

Explain in detail about the pile foundations, Explain in detail about the P...

Explain in detail about the Pile Foundations Where the support given by top soil is not sufficient and the load has to be carried deep down for purposes of stability and contro

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd