Mr.. Gandhi,
Electrode selection is not correct.
Meeting tensile and impact requirements(@-46 Degc) on the PQR with E-7018-1 welding electrodes, under normalizing condition will not be easy. Under the best condition one may just scrape through.The reasons are a as follows:-
- both SA-516-70 BM and E-7018-1 weld metal conforms to C-Mn steel chemistry. Mn does not exceed 1.2% in BM and 1.6% in WM.
- Base metal undergoes grain refining during processing(rolling other forming) ,in addition the final refining done through normalizing
- On the contrary weld is cast structure, which will marginally get grain refined during normalizing.However the initial grain size will depend a lot on the heat input and and interpass cooling control.There's no grain refinement through forming.
On a normalized E-7018-1 weld metal the mechanical strength may match the same of the BM. However to match the impact properties one needs more alloying elements, such as Ni, Mo .......
Ideally speaking E-8018C3 or E-7018C3L should be the choice to the choice for SMAW electrode. If there's hardness restriction of 22HRC max, E-7018C3L may be a better choice.
The other option is E-8018D3(Mn-Mo) type electrode.However you have have higher weld/HAZ hardness.
For the BM what's the rationale to perform impact test @-57 Deg C. SA-516/70 is never designed for such low temperature. If the selection has to be within C-Mn family then SA 537Cl1 or Cl2 steel would be a better choice.
Look at SA-20 Table-A-1.15 for allowable impact properties for various ASME/ASTM steel grades.
Note : please go through the blogs, there were similar problems discussed in the past.
Thanks.
Pradip Goswami, P.Eng,IWE
Welding & Metallurgical Specialist
Ontario, Canada
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Gopalakrishnan G
Sent: Saturday, August 23, 2014 11:16 AM
To: materials-welding@googlegroups.com
Subject: Re: [MW:21676] Notch Toughness Properties of WPQR.
please check Test certificate of your electrode (impact value specified by manufacturer) and what is the interpass temp maintained? more heatinput may also affect your impact.
On Sat, Aug 23, 2014 at 11:19 AM, 'CHINTUKUMAR GANDHI' via Materials & Welding <materials-welding@googlegroups.com> wrote:
--Dear Experts,Greetings of the day.I came to an issue in WPQR of P No. 1 Group 2 Base metal in CVN Impact testing of weld and haz. Design Code is ASME Sec. VIII Div. 1 Ed. 2013 & ASME Sec. IX Ed. 2013.Base Metal Thk. 25 mm. SA 516 Gr. 70PWHT: Normalizing at 920+/-10º C.Holding Period 65 Minutes.Welding Process SMAW (Manual)Electrode Used: 3.15 & 4.0 mm. E7018-1 (Impact tested in as welded condition).Position: 3 G Uphill (Stringer/ Weave Bead)CVN Impact test results of HAZ:Test Temp. -57º C (Temp. reduction applicable)Specimen size: 10 x 5 x 55 mm.Values in Joules HAZ Top Side- 5, 19.5, 4 (Average 9.50)Values in Joules HAZ Bottom Side- 4.5, 4, 17.5 (Average 8.67)Values reqd. for sub size specimen: Individual min. 8 J & Min. Average 10 J.CVN Impact test results of Weld:Test Temp. -46º C (Temp. reduction applicable)Specimen size: 10 x 10 x 55 mm.Values in Joules - 9, 14.5, 8.5 (Average 10.67)Values reqd. for Std. size specimen: Individual min. 16 J & Min. Average 20 J.What shall be the reason of failure? Is electrode selection OK?Awaiting for your prompt favorable response at the earliest.Thanks & regards,C. R. GANDHI
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G.Gopalakrishnan
Welding Engineer
Mukand Ltd
Mumbai
Moble :+91-9833397917
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