Welding 4140 and Mild Steel

Hi, as those 41XX and 43XX alloys are pretty good for heat treating, you better be aware of somethings:

You are surelly inducing a higher strengh by welding process, locally quenching the material. Annelling always help, but you mentioned 900F, which is about 480 degC. The temperature range around 450degC is dangerous because it causes a phenomen called temper secondary hardening. You better consult a good source like metals handbook to determine if you should use a lower temperature in longer time or higher temperature to normalize the material at all...

Is there a way to reduce the amount of weld used? This is always a good idea when working with high strenght steel.

What is your weld wire, joint design, pre-heat and interpass temp.?

If you formed excess martensite and have hydrogen induced cracking it will be too late to normalize afterward.

I have been taught that it is never a very good idea to weld hard material to soft material. However, when it does need to be done, I have had very good luck with using stainless or high nickel welding rod. It seems to work best for fusing metals of different chemistry. I have been able to weld cold roll steel to cast iron using stainless arc welding rod. I would not trust it under a heavy load but it did hold much better than I expected. Try stainless rod!!!!!

Preheat the buggers to 900 F and use a SS 309 or 310 electrode, let the weldment slow cool to room temp.

Mr. Davis,

Proposal #1:

Pre-heat both the shaft and plate to 600-800 degrees F use stainless 300 series rod cover with insulation blanket or warm sand to slow cool.

Proposal #2:

Pre-heat both the shaft and plate to 600-800 degrees F there is a special underlay rod to join the two dissimilar metals together. Contact your weld rod manufacturer they can assist you with the selection of the correct rod materials and procedure. You may have to use a build-up rod and another rod to then join the shaft and plate together. You will want to slow cool with insulation blanket or warm sand.

Additionally:

The 4000 series shaft material may be breaking in the heat affected zone and not the weld itself. This is due to the higher carbon content and crystallization thus pre-heating and slow cooling should help eliminate or reduce the breakage.

Proposal #3:

You may have them friction welded I knew of a company that used this method to bond a shaft to a drive gear of dissimilar steel chemistries.

Proposal #4:

Depending on the size of plate and shaft you may wish to contact a forging company to produce a one-piece forging thus eliminating the welding altogether this would result in a stronger design perhaps reducing the size and weight.

Good luck,

Forge_1@hotmail.com

Try friction welding. Its all the rage in Aerospace for joining dis-similar materials. They friction weld turbine wheels in turbochargers and engines. They will also have ideas on the specific pre-treatments.

Have you tried brazing them?. Check with your welding supply and or AC shop supplier.

I have a good luck with brazing them.

Try it

Armanto

ME

For Inertia Welding, contact Pierce Industries in Rochester, NY. They did some 4140 weldments for us.

Preheat to 400 before welding use oxwell65 welding rods cover with blanket let cool slowly then stress relieve in furnace

I've repaired 5" 4140 boiler grate drive shafts, welded to large 8620 couplings. The keyways had fractured. The repaired shafts ran 1 year without problem, then we replaced them. No cracks after 1 year.

Preheat = 600 F. E11018-M stick rod, stringers only, 1/2" max bead width. PWHT with electric pads, 1100 F 2 hours, slow heatup & cooldown. PWHT is vital, do not skip the PWHT. MIG would work fine too. We were field welding and thus used stick.

A critial item is to check your weld design strength. Check the loads you are putting across the welds. See Lincoln's Blodgett handbook if you need a design reference.

I've also used plain carbon steel rod E7018 in lower stress welds, such as welding carbon steel to 4140 or 4340. Follow same preheat and PWHT. Works great, just check your weld's design strength.

I weld 4140 every day bottom line is your not gonna have any luck unless you get 4140 plate toweld the shaft to then u should preheat to about 250-300 F and weld it up with E9018 if you weld at the right temp it will last longer than any other combination

We use some large components with 4140 (equivalent) forgings welded to carbon steel plates, And we have never experienced any problem.

You mentioned "4140 comes anneled ansd harnded"

Is it annealed/ normalised/ Hardened and tempered ? because this combination do not ring a bell.

You are not normalizing but stress relieving that also incomplete (900^o F = 482^oC)

If you want to temper- first harden to 830-880⁰C then temper 450-700^oC in still air (not in oven) - and this is likely to land up in crack due to dissimilar material joints and the HAZ/Weld Zones.

Usual procedure what we follow is to just go ahead with stress relieving at 500-550⁰C for the HT condition forgings. And in case you are with Annealed Rods - go for slightly higher SR Temperature (600-650)

Ensure preheating to 200^oC before welding.

Note I am talking in ^oC- takes an effort to convert into ^oF

also try to controll your interpass temperatures there are formulas for heat into the part and the time you should wait to let some of it come out this will minimize the heat affected zone i belive steels ranging from .29% to .65% carbon are weldable as long as pre post and interpass temps are monitored properly im not sure if there is a way to completely eliminate all of the martensite formation in the heat affected zone but it can definetly be reduced. having the oven is definetly a plus i think you may be trying to put to much heat into the part at one time run the rod at the low end of the range and monitor with a pyrometer there are charts for determining the proper heat range without changing the structure of the steel although im sure some changes are unavoidable but minimizing them may give you what you need. also another genleman mentoing consulting someone for rods i suggest arctech welding rods they are more expensive but they are worth it also if you cannot find these any aws standard rods (blueshield 7018 or 8018) have low hydrogen content and low iron powder content in the core whis is ideal for preventing cracking also be sure to incorperate something in your design to assist in aligning and holing the shaft in place like a spigot on the shafts end inserted into a hole in the plate. chamfers also help the more surface area the better usually but only try for more surface area if you are sure you have found the information necessary to to keep the formating of martensite to a minimum. also im not sure that 900f degree preheat is necessary seeing how most steels start to change stucture at the 600c area welding after 900f pre may bring you over the limit very quickly but you definetly need to pre heat to some degree

How much is it for i really need the price right now if somebodyy could help me.

Pls!!!!

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