My question is this; if the color is good is the ss material good to go? In other words, can you have two identical parts with identical colors but different strength and corrosion resistance based on heat input?
I made this tail cup shield and i can get perfect silver beads. If i just use the #12 cup on this 18 gauge sheet i can't move fast enough to get good penetration and good color. I imagine the heat effected zone is not effected by gas coverage but oxidation obviously is effected. So just trying to parse HAZ from gas coverage issues.
Thanks
Those two things are part of the same equation, but not the only two factors. If you have good color then your not going to have oxidation that’s effecting the corrosion resistance of SS. The effects of stress on the SS from the heat of the haz is unavailable. Even with good gas coverage you still have stress from having one area of SS that was molten being connected to an area of SS that wasn’t.
I guess my concern is that i was able to get colorless (silver) beads even though i had the metal red hot. As long as i keep gas until it cools i get excellent color.
This question depends a lot on the type of stainless being welded.
An austenitic stainless like 304/316 won't be affected much by the heat of the base metal and as long as you keep it covered in gas then the corrosion resistance should not be affected and neither will the grain structure. This type of stainless does not harden by heat-treating.
It becomes a different story on martensitic and some types of duplex and precipitation hardening stainless types which are heat-sensitive and will harden in the HAZ. Depending on the application on these you will either need to keep your base material temperatures low (eg. clamp chill blocks or cooling paste around the area) or be able to (re-)anneal and then heat-treat the whole welded structure.
You could keep these nice and silver with an argon cover but end up with a brittle and cracking HAZ anyway..
But on these types of stainless you'd usually get input from an engineering dept. with specific guidelines on interpass temperatures and after-treatment and such.
Arno wrote:This question depends a lot on the type of stainless being welded.
An austenitic stainless like 304/316 won't be affected much by the heat of the base metal and as long as you keep it covered in gas then the corrosion resistance should not be affected and neither will the grain structure. This type of stainless does not harden by heat-treating.
It becomes a different story on martensitic and some types of duplex and precipitation hardening stainless types which are heat-sensitive and will harden in the HAZ. Depending on the application on these you will either need to keep your base material temperatures low (eg. clamp chill blocks or cooling paste around the area) or be able to (re-)anneal and then heat-treat the whole welded structure.
You could keep these nice and silver with an argon cover but end up with a brittle and cracking HAZ anyway..
But on these types of stainless you'd usually get input from an engineering dept. with specific guidelines on interpass temperatures and after-treatment and such.
Coldman wrote:For 18# staino, to achieve peno and good colour you need pulse. What power source are you using?
Yes that makes sense. I have the dynasty 210dx and the pulse works great.
Can you guys elaborate on how you're using pulse in this case? Most stainless I'm welding is just a little thicker than what's being discussed here, and I'm trying to limit heat input too. I've tried various pulse combinations with limited success. Best pulse config I've found is a "slow" pulse, matching my fast dab rate of 1.5 to 1.8 per second. Maybe 30% background amps and 40-50% on time. Improvement is not all that dramatic and I often feel more comfortable with no pulsing and just trying to move quickly with modest amps. If it makes a difference, I'm usually welding without any kind of backing to cool the piece or keep atmosphere out. I've tried fast pulsing (30/second and up), and while it helps keep the puddle from wandering over edges, etc. it hasn't been helpful in this situation.
I've seen some folks in videos using big, slow pulses that are very narrow, with low background amps. Almost like a series of spot welds. I tried that a little but haven't been able to make that work in a useful way.
That's what I love about this site. You can screw around with settings trying to find a the sweet spot and just go round in circles, then you log on here and ask - and just about always you will receive.
So for 18# staino with your Dynasty 210, try these settings:
Peak current 48 amps
2.5 pulses/sec
50% on time
50% background current
3/32" 2% lanth
No.12 cup
Argon, 15 L/min (32cfh)
backing bar or purge
autogenous (but I always keep some 1/16" filler on hand just in case)
Method:
use peddle on corner to puddle without depleting the corners, after that mostly you will be full peddle but adjust for colour.
as soon as puddle appears start stepping with the pulse in a straight line, no weaving.
step further than you think to keep motoring and stacking dimes, that way you don't overheat.
step distance also affects peno, practice this a few times to get it right. Look for tiny fish eye at edge of puddle, that means you're penetrating fully.
When you finish, keep post flow on it till times out - 9 sec.
Needless to say your fitup has to be perfect. Any gaps and you will become sad and maybe say some bad words.
Something to consider is the difference between power and energy. If you run a bead at 50amps for 60 seconds and your voltage was 35v that would be 105,000 joules. If you ran 180amps 10% peak 5%bkg for 60 seconds that would be 54,810 joules! Almost half the energy.
The 180ams is only on for 6 seconds, producing 37,800jouls.
The 9amps is on for 54s and produces 17,010j
So try high amps for a short time.
On 18 gauge
I would set my pulse to about 1-1.2.
Amps 160-200
Peak time 5-10%
Background 5%
Cheers
I think this outside corner was something similar
Simclardy, I have been thinking in terms of energy too, so what you said makes sense. Total and average energy should matter most, though I guess you also have to think about how fast the heat dissipates into the weldment and the energy used to melt the filler. Maybe too much too fast blows a hole? I've been making some current and waveform measurements similar to the ones you did, to understand how the welder actually behaves, and thinking about which waveform imperfections matter. Pulling that together and replying to that thread will have to wait for another day. For now I want to make progress on the stainless tubing welds.
I've tried pulsing as you describe--sort of. I think the short on-time and low background amps you specify are right at the limits of my welder, and I can do it. However I don't think I've tried amps as high as you suggest. I assuming you are dabbing on the high amp pulse? 0.045" filler rod? I'll be making mostly fillets, and a few butt joints.
I'll try this and see what I can do. Also work on the approach Coldman described. And have the beer AFTER the welding.
EngineerIsWelding wrote:Simclardy, I have been thinking in terms of energy too, so what you said makes sense. Total and average energy should matter most, though I guess you also have to think about how fast the heat dissipates into the weldment and the energy used to melt the filler. Maybe too much too fast blows a hole? I've been making some current and waveform measurements similar to the ones you did, to understand how the welder actually behaves, and thinking about which waveform imperfections matter. Pulling that together and replying to that thread will have to wait for another day. For now I want to make progress on the stainless tubing welds.
I've tried pulsing as you describe--sort of. I think the short on-time and low background amps you specify are right at the limits of my welder, and I can do it. However I don't think I've tried amps as high as you suggest. I assuming you are dabbing on the high amp pulse? 0.045" filler rod? I'll be making mostly fillets, and a few butt joints.
I'll try this and see what I can do. Also work on the approach Coldman described. And have the beer AFTER the welding.
I used 16 gauge filer because that's the smallest i had. On outside corners it can be done without filler.
I am dabbing on the high amp. At some point its more like placing the wire in position and then blasting it together. The low amp preheats the filler and maintains an arc and the high amp does the work. As for burning through, not a real problem. If it is just shorten the time of the blast.
It's nice to hear your interest in the waveforms generated by welders. I am not an expert but i would love to just see the waves of all different welders. I don't enjoy sales men inventing adjectives for how good their product is, just show me.
Which reminds me it's a voting day in massachusetts! Lol
Cheers
Input to output ratio is rarely linear. Just because the out put energy is less does not mean the power consumption on the intake is less. That’s why welders have large heat sinks on the inside.
Poland308 wrote:Input to output ratio is rarely linear. Just because the out put energy is less does not mean the power consumption on the intake is less. That’s why welders have large heat sinks on the inside.
That's why i wanted to just focus on the output energy. On a constant current machine the voltage will not stay at a given voltage like 35v but i am using this as an average to illustrate the difference between quick burst of high amperage, and a constant moderate amperage.
