1045 vs 1055 hardening

[odipete]

Hello,

I would like to find out what is the difference in cutting/stability performance between 1045 and 1055 steels when they are harden to their optimal hardness.

From my research I noted that majority of knife manufacturers prefer 1055, why if 1045 is apparently more cost effective?

Thanks
pete

 

[NickE]

1055 is going to be harder would be my first guess.

 

[redpicker]

As you have posed the question, I'd have to say that NickE has the best possible answer.

The first two digits of the steel grade (10) indicate a plain carbon steel (no alloying elements other than a small amount of Manganese). The last tow digits (45 or 55) list the aim carbon content (that is 0.45% and 0.55%). Carbon has a very strong effect on the hardness of the steel, in all conditions. So, with both steels in the same metallurigcal condition, the 1055 will be harder.

The optimum hardness for a steel is very dependent on its application. The optimum hardness for a steel nail would be very different than for a steel drill bit. You mention kinves, and to hold an edge, it is very important for the blade to be very hard, so I'd guess that in this application, they are really after maximum hardness.

The maximum hardness of a steel is nearly entirely dependent on carbon content. As carbon increases, so does maximum hardness. This relationship begins to level off at around 0.60, so, for for some knife applications, there may not be much advantage to exceeding 0.60% C, hence the choice of the 1055.

You also mention that 1045 being more cost effective. Why do you believe that? There are many factors that enter into cost, but the base carbon content is not generally one of them. You would have to examine the factors that are making the 1045 more cost effective to understand the trade-off between maximum hardness (edge-holding ability) and cost.

rp

 

[odipete]

thanks for your input.

our knife supplier has changed from 1055 to 1045 - apperantly due to cost savings??. they assured us that we will not see any performace change but our customers are complaining of bending blades so I trying to figure out what happened. the hardness and heat treatment specs are similar, chemical composition is somewhat similar but the only "big" difference is carbon...

thanks
pete