By HeidiK
Date 02-22-2019 07:19
Hello,
Any suggestion how to decrease hardness?
Allowed maximum hardness: 210 HV10 (base material/HAZ/weld)
(Also impact requirements; -46C at least 27 J tranverse or 40 J longitudinal. (Values ar average of 3 tests with minimum values 21 J trans. and 30 J long.))
Material: SA333 Gr6
Welding process: GTAW (TIG)
Welding consumable: ER70S-3 (Böhler EML5)
Material thickness: 7,1 mm
Outside pipe diameter: 48,3 mm
Joint type: BW ss nb ml
Welding positions used during tests: PH, PC
Tungsten electrode type/size: WT 20 / 2,4 mm
PWHT: Temperature 620 C +/- 20 C; time 2 min/mm (at least 20 min); Heating rate 50 - (500/s) C/h, max 200 C/h; Cooling rate 7000/s C/h, max 275 C/h
Welding test No. 1:
After each run the material/weld were cooled under 200 C (in air) before welding next run.
PH 1, 2, 3... : 90-120 A, 8-12 V, DC-
PC (PB) 1, 2, 3... : 95-125 A, 8-12 V, DC-
Measured hardnesses:
- base: 1: 146-149 HV10; 2: 146-148 HV10
- HAZ: 1: 165-192 HV10; 2: 164-198 HV10
- weld: 1: 175-253 HV10
Welding test No. 2:
After each run temperature was kept over 200 C and top layer of weld was welded by using 2 runs.
PH 1, 2, 3... : 100-130 A, 15-18 V, DC-
PC (PB) 1, 2, 3... : 100-130 A, 15-20 V, DC-
Measured hardnesses:
- base: 1: 145-147 HV10; 2: 145-147 HV10
- HAZ: 1: 159-169 HV10; 2: 162-183 HV10
- weld: 1: 136-220 HV10
(Question is also in Metallurgy section)
I am facing 3 hardness test for 3 different processes for an upcoming project. 1 in which is GTAW using ER70S-2 filler metal. I have to say you now have me concerned to say the least. Testing should begin sometime in the beginning of March. I can post the results for the GTAW process when I get them back from the lab. I know this is not helping you In regards to your question But it should help you gain knowledge into the two different filler metals and their respective hardness. Variables are pretty much the same by the way other than the filler metal and the PWHT time range. Now that I think about it, the variables are widely different but I’m sure you’re picking up what I’m laying down.
Regards,
Jamie