Tool steels

Question 1

Tool for highly abrasive materials
(minerals)

Answer 1

• Fe based
• Used to processing minerals
  -Complex loading conditions, cyclic stresses, friction, wear, corrosion
• The surface of the tool must withstand hevy duty, pressure and relative moments

Question 2

Strategies to withstand heavy wear conditions

Answer 2

• Increasig hardness, martensitic phase.
• Small and well dispersed carbides for tool edge
• On the contrary wear from gravel si optimally protected by coarse carbides or borides
• The hard phases have to be harder than the abrasive material
• Hard phases have to be more tough at fracture than the abrasive, in this way will be the ab grain to fracture.
• The matrix has the task of supporting the hard phases

Question 3

Proprerties of matrix for heavy wear cond

Answer 3

• High hardness
• High YS
• Certein degree of ductility

Question 4

types of tool steels for heavy wear condition

Answer 4

• Normalized low-C steel
• Pearlitic steels
• Spring Q&T steels
• Surface hardening
• “ledeburitic” chromium steels

Question 5

Hardfacing alloys procedure

Answer 5

• improve surface abrasion-corrosion resistance
• A protective layer is applied by welding on cheap substrates
• the range of coating materials spans from simple martensitic steels to super hard pahses up to 6% C

Question 6

hardfacing/cladding

Answer 6

• Deposition of a material with superior properties by welding
• For preventive purpose or for remedial purpose
• Cladding uses a overlay material similar to the base one but with improved properties

Question 7

Cladding vs thermal spray

Answer 7

• Cladding is a welding operation aimed to creating an homogenous layer of filler on the surface.
• Thermal spray is a process consisting in a gun with a flow of powder of metallic or ceramic or composite elements heated in the basic metal zone.

Question 8

Tools for less hard materials

Answer 8

• The shape of the tools is preserved using different hardness value (polymers 30-35 HRC mhot metal working 40-50 HRC cold metal 55-65)
• Service hardness is reached by hardening and tempering steels with dissolved carbon, dissolved alloy elements, alloy carbides.

Question 9

Features of the tool steels based on kind of workin (cold, hot,…)

Answer 9

• Cold working tool steels high hardening capacity with carbides to improve wear resistance
• Hot working tool steels increased creep resistance with precipitation hardening
• High speed tool steels containing carbides in a creep resistant hardened matrix.

Question 10

Cold work tool steel

Answer 10

• Used at room temp
• Divided according to C content

Question 11

Hot work tool steel

Answer 11

• service temp 400-1200 °C
• Creep resistantand high-strength Q&T steels
• Oxidation resistance austenitic steels and nickel-based alloys