Technical Information

 
 
 

Comparison of Cast vs. Fabricated Chain

I'ANCO ALLOY 2A/QT/380 FABRICATED C-Mn
I'ANCO Alloy 2A (similar to 8630) has a combination of high strength and low temperature toughness. The combination of alloying elements produces a quenched structure consisting almost entirely of martensite. Upon tempering, this structure provides the best combination of strength and toughness. The presence of nickel adds to low temperature toughness. Lower hardenability due to the absence of Cr, Ni and Mo make it more difficult to produce tempered martensite structure of equivalent hardness and toughness. The absence of nickel also reduces the low temperature toughness. Under extremely low ambient temperatures, this alloy may be more susceptible to failure.
I'ANCO Alloy 2A castings are quench and tempered for maximum toughness. Typically bar stock is not supplied in QT form and must be heat treated if a quench and tempered product is desired. Other means of providing surface hardness do not create a uniformly hard and tough cross-section.
No welding is performed after the links are quenched and tempered. As a result, the entire link consists of metal of equal hardness and toughness. There are no residual stresses that act in an additive manner with external forces to produce a premature failure.

Cold forming of side bars results in residual stresses and strains that can contribute to premature failure.

Welding produces a complex structure consisting of base metal, weld metal and a heat affected zone. Thus, the link does not consist of homogeneous material of equal hardness and toughness. Without post weld heat treat, components can exhibit significant residual stresses.

The homogeneous nature of the cast link results in the entire cross section performing equally as a load bearing member, with equal toughness and strength at the surface. Surface hardening can enhance the load bearing capability of a link and can increase its fatigue strength, provided that the combination of applied and residual stresses do not exceed the elastic limits of the link. In such cases the harder but less plastic surface layer can crack and accelerate failure.
Blended intersections of side bars with the link barrel reduces stress concentrations in critical areas. Welded link-barrel junctions typically have higher stress concentration factors and have weld-related structural changes and potential weld defects in this critical area.
The larger cross-section of the cast link results in higher load bearing area, not only regarding tensile loading but also with respect to sliding wear.