Question

Calculate the relative amount of each structural constituent and phase based on the iron-carbon phase diagram.

1. Normalized low carbon steel

2. Normalized 4140*

3. Water quenched 4140*

4. Oil quenched 4140*

Answer 1

ANSWER:

The iron - carbon phase diagram up to 6.67% at 6.67 % C, the microstrructure of steel is 100%. The iron carbon phase diagram consists of three inverient reactions like -peritectic,eutectic aand eutectoid reactions.The iron -carbon phase diagram as shown below.

To Calculate the relative amount of each structural constituent and phase based on the iron-carbon phase diagram.

• The heat 870 C to 9250 C to hold the maximum thickness 25mm at air cool rate 15oC/h
• The heat 1600 F to 1700 F and hold for a minimum of 1h, or 15 to 20 and thickness 25 mm. Air cool at a rate about 15oC/h then air cool.
• The final heat treatment at the lower temperature at normalizing process
• The nominal normalizing temperature for 4140 grade is 1600 º F.
• In Normalizing to refine the structure of forgings that cooled non-unform.
• Normalizing heat 845 to to hold the maximum thickness 25mm , where air cool more restrictive normalizing temperature.
• Quenching to Rapidly remove material plunge it into a large amount of oil or water at room temperature , for1 hour until equilibrium temperature and corresponding solid solution
• The quenching in hot temperature at 570oC to 750oC hot oil quenching is used for carburized steels, lower bainite materials.