Low Impact properties of 4130 Steel
Low Impact properties of 4130 Steel
(OP)
Does anyone have experience of improving the Charpy impact properties of 4130 steel @ -101C in the hardened and tempered condition?
Although general structures and tensile properties are good, Charpy Impact results are as low as 10 to 15 Joules despite good control of heat treatment and testing methods
Although general structures and tensile properties are good, Charpy Impact results are as low as 10 to 15 Joules despite good control of heat treatment and testing methods





RE: Low Impact properties of 4130 Steel
RE: Low Impact properties of 4130 Steel
RE: Low Impact properties of 4130 Steel
RE: Low Impact properties of 4130 Steel
The carbon content has the biggest effect on impact values for low alloy steels. The next biggest driver is prior austenite grain size - a course grain size prior to transformation will lower impact values.
If I had to guess, I would suspect your prior austenite grain size was larger than desirable to drive the impact values to being lower than expected.
RE: Low Impact properties of 4130 Steel
Our customer is looking for minimum 27 joules
RE: Low Impact properties of 4130 Steel
RE: Low Impact properties of 4130 Steel
RE: Low Impact properties of 4130 Steel
Hot forged, then quenched & tempered.
Would agree fully about cleanliness & grain size but will be very unlikely to get GS of higher than 7.
RE: Low Impact properties of 4130 Steel
RE: Low Impact properties of 4130 Steel
Petrotrim Services
RE: Low Impact properties of 4130 Steel
RE: Low Impact properties of 4130 Steel
There are steel producers that market modified 4130 chemistries (increased Mn, Cr, and Mo, with improved cleanliness) that will get you there.
rp
RE: Low Impact properties of 4130 Steel
A nickle alloy is not cheap, but after all that special processing you may still fall short on impact properties for such a low temperature. The higher cost may also be ofset by avoiding a service failure.
I reviewed a few Nickle 718 alloy test reports that a for an API type application,the charpy test was performed at -75 F(-59.4C) with impact values that range from 40 ft/lb(54 J) to 50 Ft/lb(67.8J). The yield strenght averages 130 KSI (896 MPA).
Obviously, 718 is not the only option.
RE: Low Impact properties of 4130 Steel
I think metengr is suggesting nickel alloy steel, as opposed to a nickel alloy. I concur with that also.
RE: Low Impact properties of 4130 Steel
I'm a little confused by your statement about prior austenite grain size. The austenitic grain size is not going to change due to thermo-mechanical work. It is established during the casting/solidification of the material. I think you are looking at the ferritic grain size which can be controlled by thermo-mechanical work.
In all of the above statements noone has asked yet how the material is being quenched. Induction versus a longer hold austenitize. This along with the austentize temperature will change how much carbon goes completely in solution. I would assume that the heat treater is austentizing at a temperature sufficient to get the carbon in solution, but it doesn't hurt to ask.
I agree that nickel should help the Charpy impact toughness of the material. And I have heard from a few suppliers of mine that a small additional of titanium will also help improve the Charpy impact toughness as it binds with some of the excess Nitrogen.
RE: Low Impact properties of 4130 Steel
It was provided by the poster -
RE: Low Impact properties of 4130 Steel
I think I phrased my statement incorrectly. What I was trying to find out was the austentizing procedure. A induction heated and quench and tempered product vs. a continuous/box furnace heat will produce different Charpy results.
RE: Low Impact properties of 4130 Steel
The austenite grain size is very much affected by the temperature at which hot working is performed. I suggest you review some references on the subject. Here is one:
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