Garbuzova КР2 Option 43

1. Springs made of steel 65 after properly tempered and tempered
Have a hardness significantly lower than required by the specifications. What caused this
Defect and how can I fix it? Indicate what kind of hardness and structure provide high
Elastic properties of springs.
2. As a result of heat treatment, the gears should receive a hard
Wear-resistant surface layer with a viscous core. For their manufacture, steel
18HNMFA. Decipher the composition and determine the group of steel for the purpose. Assign Mode
Thermal and chemical-thermal treatment, give its justification, explaining the impact
Doping for transformations occurring during the heat treatment of a given steel. Describe
Microstructure and properties of steel after heat treatment.
3. For parts operating in an oxidizing atmosphere, steel 08X18N12T is used.
Decipher the composition, explain the purpose of chromium in this steel. Justify the choice of steel for
Of these working conditions.
4. For worm pairs, bronze BrOTSS4-4-17 was chosen. Decode the composition, explain
Purpose alloying elements and high antifriction properties of this bronze.
5. Indicate the main features of plastics as a structural material and
Recommendations on the use of plastics in machine building.