Re: [MW:33228] Hardness Issue on weld metal

Hi Williams P Wilson,

following points to be verified before going to further details for investigation 

1. Have you checked for consumable mechanical properties with heat treatment conditions before using it PQR qualification ..? 

2. Have you verified Harness on base metal ? 

3. What is the tempering temperature of base material? 

4. Have you Checked Consumable certificates  before welding?  Are your consumables are guaranteed for PWHT applications? 

5. Have you tried other hardness methods for cross verification??

In general PHWT will not increase/affect the hardness, it is just for relieving the stresses only ,On the other hand, PWHT is usually in the same temperature range as the tempering heat treatment operates. Therefore, you should expect the same effects & results which include an increase in hardness. In such cases some of the codes and standards are recommending to control the PWHT temperatures just below 25-30 deg C below the tempering temperatures to control the mechanical properties.

you should check the filler metal certificates and data sheets for better understanding of weld metal mechanical properties before & after PWHT ,  check PMI of weld metal which will give some clarity to easily spot elements  which cause high hardness. 

Regards,

Srinivas Rao 

Welding Engineer

On Wed, Jul 13, 2022 at 3:22 PM williams p wilson <williamswilsonp@gmail.com> wrote:

Dear Experts,

During the PQR qualification of ASTM A 519, Grade 4130 , Pipe 3" x Sch XXS material hardness value in SMAW weld metal area observed in b/w 247 to 283 HV.

The required value is in blw 201 to 241 HV, Base metal hardness also is in the same range.

Preheat temperature : 200 ° C

Interpass temperature : 300 ° C (Max)

Stress relieving details as follows,

600 ° C ± 10  ° C, Holding Time : 01 Hour

Cooling Rate : 150 ° C / Hour
Heating rate : 150 ° C / Hour
Unrestricted heating up to 300 ° C
Controlled cooling upto to 300 ° C

Please reply with your valuable comments to reduce the high hardness observed in the weld metal.

Thank You & Regards

Williams P Wilson

QA/QC Engineer

Welding Inspector (CSWIP 3.1)

Cell: (+968) 94600828

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