Are there benefits to using alloy ACME screws like Alloy 4140 Heat Treated steel in place of the low and medium carbon steel screws offered as standard?
Alloy 4140 Heat Treated is only beneficial in very specific situations and is commonly “over specified”. This is mostly because it is a popular material for bolts and fastener threads. Many users specify Alloy 4140 HT with the goal of increasing the wear life of the screw, but most screws are used with bronze or plastic nuts and a sufficient hardness differential exists between these materials and all steels such that performance of the nut materials is not affected. Alloy 4140 HT is also specified in the belief that it will enhance the stiffness of the screw. However, the stiffness of the screw is a function of the modulus of elasticity, which is the same for all steels, so elastic deflection under load and column performance will be the same. If strength is a concern as it may be on parts for aerospace or other weight sensitive applications then alloys may be desirable, however, most strength applications are better solved by using a larger size carbon steel screw in place of a small
