Material of Motorcycle Connecting Rod
A motorcycle connecting rod is required to be hard (HRC60) at bore area, and it is required to be ductile at rod area. Therefore, the chromoly alloy steel is applied for the motorcycle connecting rod. For the traditional application, SCM415/SCM420 or 15CrMo4 is the most commonly used low-carbon alloy steel. After carburizing heat treatment, the surface hardness is increased to HRC60. The abrasion resistance is increased. Meanwhile, the strength is still good at core area.
SCM415 Material Composition:
|
(C)% |
(Si)% |
(Mn)% |
(P)% |
(S)% |
|
0.13-0.18 |
0.15-0.35 |
0.6-0.85 |
0≦0.03 |
0≦0.03 |
|
(Ni)% |
(Cr)% |
(Mo)% |
(Cu)% |
|
|
0≦0.25 |
0.9-1.2 |
0.15-0.30 |
0≦0.3 |
|
For higher power engine or modified engine, the strength of SCM415 may be not enough. A higher strength nickel-contained chromoly alloy steel is used to replace traditional SCM415. Generally speaking, the more nickel dissolved in the steel, the higher ductility or the higher yielding strength it becomes. A popular nickel-contained chromoly alloy steel is SNCM220. The yield strength of SNCM220 is 10% higher than SCM415, then providing more strength and safety of connecting rods.
2020-10-16