×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Low Impact properties of 4130 Steel
2

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

RE: Low Impact properties of 4130 Steel

What was your heat treatment? Tempering temperature?

RE: Low Impact properties of 4130 Steel

(OP)
water quenched & tempered @ 700 C
 

RE: Low Impact properties of 4130 Steel

I just noticed that your impact test temperature is -101 deg C? Is this value correct or should it be -10 deg C?

RE: Low Impact properties of 4130 Steel

At this point I am going to assume your impact test temperature was -10 deg C for the stated values.


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

(OP)
Thanks guys but -101 C is correct!
Our customer is looking for minimum 27 joules

  

RE: Low Impact properties of 4130 Steel

Can you consider double tempering. How much was the retained austenite after tempering.  

RE: Low Impact properties of 4130 Steel

The impact toughness of almost any martensitic steel is going to be quite low when tested at - 101 C.  If you must use 4130, then you will need to have an extremely fine prior austenite grain size in order to achieve good toughness.  This means an ASTM number of 8 or higher, preferably 10 or higher.  In order to achieve this, the hot-rolled material (bar, rod, plate, etc.) should be thermomechanically rolled, also called controlled rolling, with a lower rolling temperature.  Then the heat treating process must use as low an austenitizing temperature as possible, meaning 845 C rather than 870-900 C.  Also, the steel must be extremely clean, meaning S ~ 0.005 or less, little O & N, inclusion modification using Ca, with ASTM E 45 levels of 1/2 or less.  Unless you have a close working relationship with your steel suppliers, then I doubt you will be able to obtain 4130 that meets all of these parameters.

RE: Low Impact properties of 4130 Steel

(OP)
This part is a forging made from steel bar of grain size of about 6/7. Forgot to mention that!
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

Then in my opinion, you will not achieve the requirement of 27 J at - 101 C.

RE: Low Impact properties of 4130 Steel

Can you use other material such as A350 LF3 Class 2. That material will meet your charpy requirements.

Petrotrim Services

RE: Low Impact properties of 4130 Steel

Agreed, you will need to change material to meet 27 J at -101 deg C. At this point, you need nickel as an alloy element.

RE: Low Impact properties of 4130 Steel

Quote:

This part is a forging made from steel bar of grain size of about 6/7. Forgot to mention that!
Hot forged, then quenched & tempered.
Would agree fully about cleanliness & grain size but will be very unlikely to get GS of higher than 7.
You will get improved results if you add a normalizing treatment before the Q & T.  Section size and surface condition as well as the quenching process can also be very important, since 4130 can be somewhat shallow hardening.

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

I agree with met engr that you should consider a nickle alloy.

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 agree with comments about prior austenite grain size, and the doubts about 4130 having any possibility of meeting requirements at that low temperature (-101°C).  

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

TVP,
    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

Quote (dr):

  In all of the above statements noone has asked yet how the material is being quenched.

It was provided by the poster -

Quote:

water quenched & tempered @ 700 C

 

RE: Low Impact properties of 4130 Steel

metengr,
    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.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources