Thin wires 01mm dia of 1080 steel steel of eutectoid composi

Thin wires (0.1mm dia.) of 1080 steel (steel of eutectoid composition) are heat-treated in the following ways. Determine the room-temperature microstructure of the steels that will result from these treatments by tracing and labeling the heat treatment paths on the IT diagram for 10 steel A() Water quench to room T in 1s. (b) Water quench. Reheat 1h at 400C. Air cool. (c) Water quench. Reheat 1h at 400 C. Water quench. (d) Quench in salt bath to 650C and hold 200h. Water quench. (e) Water quench to room T. Reheat to 700C for 24h. Air cool. (f) Quench in salt bath to 600C and hold 3.5s. Water quench.

Solution

1. martensite

2. Water quenching results in 100% martensite, and heating at 400C for 1 hour and air cool results in trosite.

3.Water quenching results in 100% martensite, and heating at 400C for 1 hour results in tempered martensit

4.After 4 seconds at 650C, we have 50% Fine Pearlite and 50% Austenite. A Afte 200 h, it becomes fullly bainite and then water quenching will result in tempered bainite.

5.. Upon rapidly cooling to room temperature in water, the specimen will completely transform to martensite. The second heat treatment (at 700°C for 1 h)—not shown on the above plot—will transform the material to tempered martensite. Hence, the final microstructure is 100% tempered martensite.

6.After cooling to and holding at 600°C for 3.5 s, a portion of specimen has transformed to proeutectoid ferrite. While cooling to room temperature, the remainder of the specimen transforms to martensite. Hence, the final microstructure consists proeutectoid ferrite and martensite