[MW:24816] Hardness issue on weld metal

Dear Experts
We have recently welded 1/2" thick and 1" Thick pipes, Material : AISI 4130. Our hardness requirement is 197BHN-237BHN

This pipes are groove welded to same size of the pipes, Followed by GTAW(ER100S-G) & SMAW(E10018-D2) process. Root is followed by GTAW and SMAW for fill up and capping.on completion of PWHT we observed following hardness value.

After completion of welding and PWHT, we have found hardness range of 285HBN and 265HBN on weld metal. Also we performed PMI on the weld metal to determine the hardness issue, during the result we found following chemical composition on the weld metal respectively.

 

Tabulation shows actual chemistry of the T.C

 

Chemistry observed as per the T.C
	Size	C	Mn	Si	S	P	Cr	Ni	Mo	V	Cu
E10018-D2	3.2mm	0.074	1.980	0.550	0.009	0.022		0.460	0.400
	4mm	0.068	1.940	0.510	0.008	0.021		0.690	0.370
	5mm	0.062	1.980	0.470	0.009	0.019		0.630	0.340

 

 

Tabulation shows actual chemistry after PMI inspection

 

CHOKE & KILL Line
	Chemistry observed as per the PMI											Other metals
Weldment area	C	Mn	Si	S	P	Fe	Cr	Ni	Mo	V	Cu	Ti
On Weld Metal 90°		2.00				95.33	0.047	0.807	0.486	0.03	0.024	1.2667
On Weld Metal 180°		1.966				96.616	0.033	0.838	0.486	0.00	0.058	0.00
On Weld Metal 270°		2.060				96.443	0.057	0.902	0.492	0.00	0.044	0.00
On Weld Metal 360°		2.115				96.401	0.363	0.907	0.501	0.00	0.037	0.00

 

 

 

BOOSTER Line
	Chemistry observed as per the PMI											Other metals
Weldment area	C	Mn	Si	S	P	Fe	Cr	Ni	Mo	V	Cu	Ti
On Weld Metal 90°		1.946				95.287	0.150	0.915	0.500	0.021	0.150	1.113
On Weld Metal 180°		1.992				96.362	0.152	0.932	0.491	0.00	0.152	0.00
On Weld Metal 270°		0.203				96.303	0.203	1.121	0.490	0.00	0.203	0.00
On Weld Metal 360°		0.252				96.556	0.252	0.735	0.480	0.00	0.252	0.00

 

On comparison of chemistry for actual observed in the T.C and PMI result varies accordingly, those variation exceeds the standard requirement of ASME Sec II part-C. Those variation are tabulated for your reference, also PMI is taken on the undiluted weld metal of the capping.

We suspect that due to exceed of Mn and Ti, hardness increased. Please suggest or advice on the following issues.

 

 

NOTE-

Interpass Temperature maintained: 300°C

Preheat Temperature maintained: 210°C

Regards
S.Sathish kumar

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