2.  A nut is a type of hardware fasteners with a threaded hole.
Nuts are almost always used opposite a mating bolt to fasten a
stack of parts together.
 The two partners are kept together by a combination of their
threads' friction, a slight stretch of the bolt, and compression
of the parts.
 A washer is a thin plate typically disk-shaped with a hole that
is normally used to distribute the load of a threaded fastener.

3.  Carbon steel and Alloy steel material used for Nut &
Bolt manufacturing.
 Nut mfg by Blanking and Threading. Bolt by forging
and threading.

4. Nickel Alloy Standard : ASTM / ASME SB 160 / 164 / 425 / 166 / 446 / 574 / 472
Grade : UNS 2200 / UNS 2201, UNS 4400 , UNS 8825 , UNS 6600
Stainless Steel : Standard : ASTM / ASME A/SA 193 / 194
Grade : B 8 (304), B 8C (SS 347), B 8M (SS 316), B 8 T (SS 321), A 2, A 4
Alloy Steel : Standard : ASTM / ASME A/SA 193 / 194 GR.
Grade : B 6, B 7/ B 7M, B 16, 2, 2HM, 2H, GR 6, B 7, B 7M.

6. Nut

8. Washer

9. TEE Bolt Stud Bolt Expansion Bolt
U-Bolt Hexagonal Bolt