group 1

• steel


  it is an alloy of iron and carbon
• Carbon content of up to 0.90%

  increases hardness, tensile strength, and responsiveness to heat treatment steel.
• beyon 0.90% of carbon 


  causes brittleness and loss of malleability of steel
• hardenability, corrosion resistance, machinability, ductility and strength

  agents are added to improvw
• Aluminum


  <2
• sulfur


  <0.05
• chromium


  0.3 to 4
• nickel


  0.3 to 5
• copper


  0.2 to 0.5
• manganese


  0.3 to 2
• Silicon


  0.2 to 2.5
• MOlybdenum


  0.1 to 0.5
• Vanadium


  0.1 to 0.3
• low carbon - low alloy


  Plain. High strength-low alloy
• Medium carbon


  Plain, Heat treatable
• High Carbon


  Plain, tool
• High alloy


  tool, stainless
• low alloy steel


  contains lower percentage of alloying element less than 0.2%
• high alloy steel


  contains above 5% of alloying element
• Annealing


  process is a type of heat treatment used primarily to make a material more ductile and less hard.
• annealing


  improves a material's mechanical properties
• full annealing


  used to soften steel, create second most ductile condition and create stable and uniform microstructure
• Process Annealing


  metal heated below the critical metal temperature, held at this temperature for a while, and then slowly cooled
• process annealing

  it is done at temperatures between 260 and 760
• stress relief annealing


  heated to lower temperature around 650 degrees and held at this temperature in the furnace for a period of time to remove metal's internal stress
• remove internal stress


  main aim of stress relief annealing
• spheroidizing annealing


  process used to increase the machinability of high carbon and alloy steel.
• isothermal annealing


  heated above the maximum critical temperature
• isothermal annealing


  steel quickly transforms into an austenite structure when heated above the top critical temperature
• diffusion annealing


  used to separate significant alloy steel castings and ingots from high quality steel
• diffusion annealing


  primary goals are to homogenise the composition and to remove dendritic and regional segregation from the solidification process.
• incomplete annealing


  heated to about upper critical temperature. the heat treatment process is obtained by slow cooling after thermal insulation
• annealing processes

  recovery stage, recrystallisation stage, grain growth stage