9SMnPb28 Free Cutting Steel Bar

 

9SMnPb28 is a lead alloyed free-cutting steel. It is usually being used for mass-produced parts. equivalent to Chinese standard Y15  , is an S-P composite high sulfur, low silicon free cutting steel. Machinability significantly higher than Y12, production efficiency than Y12 steel increased by 30 ~ 50%, especially tapping, tap life than Y12 more than doubled, commonly used in the manufacture of important standard parts, such as bolts, nuts, Spring seat and so on.

 

9SMnPb28 is a free-cutting structural steel. Free-cutting structural steel is abbreviated as free-cutting steel, which contains a small amount of free-cutting elements and has good cutting performance. Free-cutting structural steel is a kind of steel that uses certain elements in steel to improve the cutting performance of steel and is suitable for high-speed cutting on automatic machine tools. Commonly used elements to improve machinability are S, Pb, Ca, etc. Among them, S is the most commonly used. S forms MnS inclusions in steel. MnS is very brittle and has a certain lubricating effect. Therefore, the chips are easy to break, and the surface of the workpiece has a high smoothness. Reduce tool wear and increase cutting speed.

 

Chemical Composition:

 

  • Carbon C: 0.10
  • Silicon Si: ≤0.15
  • Manganese Mn: 0.80～1.20 Sulfur S: 0.23～0.33
  • Phosphorus P: 0.05～0.10
  • Lead Pb: 0.15～0.35

 

Mechanical Properties:


  • Tensile strength σb (MPa): 
    • (hot rolling) 390 ~ 540; 
    • (cold drawn) steel thickness or diameter:
      • 8 ~ 20: 530 ~ 755;
      • > 20 ~ 30: 510 ~ 735;
      • > 30: 490 ~ 685

  • Elongation δ5 (%): (hot rolling) ≥ 22; (cold rolling) ≥ 7.0
  • Section shrinkage ψ (%): (hot rolling) ≥36
  • Hardness: (hot rolling) ≤ 170HB; (cold drawn) 152 ~ 217HB

 

Application:

 

9SMnPb28 free-cutting steel free-cutting structural steel, executive standard: GB/T 8731-1988. The shape and distribution of MnS inclusions in low-carbon and high-sulfur free-cutting steel have a great influence on the mechanical properties of free-cutting steel. Although free-cutting structural steel contains more S and P, it is added or preserved as a beneficial element in this type of steel. Therefore, it belongs to high-quality steel. Free-cutting structural steel is used to produce standard parts such as small screws, nuts, oil pumps, watches, computers, typewriter parts, machine tools, screw rods, etc.

 

 

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