Describe the microstructure present in a 1050 steel after each step in the following heat treatments:
(a) Heat at 820 ˚C, quench to 650 ˚C and hold for 90 s, and quench to 25 ˚C;
(b) Heat at 820 ˚C, quench to 450 ˚C and hold for 90 s, and quench to 25 ˚C;
(c) Heat at 820 ˚C and quench to 25 ˚C;
(d) Heat at 820 ˚C, quench to 720 ˚C and hold for 100 s, and quench to 25 ˚C;
(e) Heat at 820 ˚C, quench to 720 ˚C and hold for 100 s, quench to 400 ˚C and hold for 500 s, and quench to 25 ˚C;
(f) Heat at 820 ˚C, quench to 720 ˚C and hold for 100 s, quench to 400 ˚C and hold for 10 s, and quench to 25 ˚C; and
(g) Heat at 820 ˚C, quench to 25 ˚C, heat to 500 ˚C and hold for 103 s, and air cool to 25 ˚C.