Weldox 700-100% martensite

[Jay_]

I recently got a job in welding weldox 700.
Type or joint is square butt weld joint.
Thickness to be welded is 6mm.
I did some calculation, and based on my inputs, it turns out that I will have a high HV hardness in the HAZ and apparently a 100% volume martensite.
This work piece shall work in tension and bending mainly.
I’m concerned…
Can anyone suggest a procedure to reverse this phase, maybe PWHT?

Detailing is a hobby,

 

[kingnero]

This is now SSAB Strenx 700 (or something similar). Readily weldable, but avoid to high heat. Read up on the SSAB website, IIRC they have a whole section dedicated to the welding of their high-strength steels.
Martensite isn't problematic as long as C% is low enough.

 

[Jay_]

Hello,
I’m not an expert in metallurgy, and material science, but doesn’t martensite make the material extremely hard? I’m concerned about the consequences on the mechanical properties of the workpiece. The t8/5 is so rapid that it will create a martensite structure in the material. I’m concerned about fatigue behavior.

Detailing is a hobby,

 

[kingnero]

Hardness of martensite is determined by (a.o.) how much %C there is. an equal carbon equivalent value with different %C will give different hardness results.
I'll let the metallurgists elaborate on this. But not all martensite is "bad"!
From a welding point of view, These materials are quite doable. Their chemistry is chosen to mitigate welding related risks. Appropriate weld filler often does not solidify to martensite, so the only problem you do have got is softening in the HAZ. I've done repairs on 1100 MPa steels recently, with elaborate testing, and using low enough welding parameters (~ 140 amps in short circuit for 6 - 8 mm material thickness), we got a welded connection with very similar mechanical values as the base material. Welding in spray arc ruined the HAZ though.

Prep properly, as cold cracking is a real risc here.

 

Go to the Titus Steel website to get recommendations. If you are inexperienced in joining wear resistant steels you definitely will need their human technical support.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[Jay_]

Thank you sir,
And fair enough i guess.
Like i previously said, i’m concerned about the HAV, not the filler metal and not the deposit.
I could anneal it, say 700 degrees c, for 15 mins and then cool it down in the furnace. But is it something necessary to do? Alternative way would be to leave it as is, but how would i know if it’s a bad martensite?? Seems a little odd actually.

Detailing is a hobby,