I would think some steels used in the Northsea applications would be required. I think some nickel would be required for cold temperature applications. I know I have seen Charypy values for -40 but not certain about -50.
In the normalized conditon, it will probably be quite low (as metengr stated, below 12 ft-lbs). It can be greatly improved by quench and tempering or by the use of micro-alloy additons to reduce grain size and other restrictions on the chemistry. In either case, however, specific testing would be required to qualify each specific heat and, perhaps, even every heat treat batch.
Thank you all for input.
Presently we cast some parts in 1045 Q&T. Min. customer requirements are TS 110ksi YS 90ksi impact strength 10 ftlbf at -50F. It varies from batch to batch, but we have no problem meeting the minimums, sometimes we get 18 ftlb. I was wandering if we can substitute 1045 to 4140 normalized, and avoid quenching just to simplify the process. Tensile and Yield should be no problem but 10ftlb impact at -50F might. I didn't find any info. in the technical literature on this particular detail. Well, next week we'll pour a sample mold and have it tested. Will let you know the results.
PS. I have another question regarding elongation problems. I'll post it a new thread.
I am interested to know your result, please do report when finish.
I honestly don't see much benefit of the substitution if you are not going to do Q&T on 4140. In addition, required strength and toughness are pretty difficult for a normalized 4140 to meet. Not impossible, but will be marginable. You probably will end up with very strict process control and often time possibly scrape some instead of simplying things.
To me, you still have to do Q&T on 4130. The benefit will be more availabe supply and possiblly higher and more consistent Charpy data.
