How to select a steel grade for best machinability and tooling life? 6

[coreman73]

In general, what are the major factors that should be considered when trying to decide between different steel grades for the same application? For example, if I want to make a simple combination wrench and have to choose between 4047 and 5046 what should I base my decision on as it relates to optimum machinability and tooling life? Cost isn't a concern here as I'm just looking for metallurgical based characteristics (i.e. hardenability, chemical composition, etc.) along with which would be most critical and the reason why.

As always, any input is greatly appreciated. At this company, the engineers are in charge of doing this so unfortunately I don't have much experience in the area.

 

[swall]

In your two hypothetical alloys, there won't be significant differences in machinability, given similar heat treat histories. As you probably already know, you have to go to the resulfurized steels to gain a big advantage. Having said that, Volvo at one time developed a machinability test involving a mill set up to record power required to make a standard cut on a specimen. I found at least one commercial lab that could do the test, but after people saw the cost, they lost all interest.

 

[TVP]

The following is a good reference on the subject of steel machinability:

Softening high hardenability steels for machining and cold forming

http://64.224.111.143/technicallibrary/nidi/literature/pdf/10028.pdf

 

[coreman73]

Excellent. Thanks guys.