Inter pass temperature selection criteria.

[anish thomas]

Dear Experts,

Can you please guide me,What is the criteria of selection of inter-pass temperature for CS, SS and DSS during preparation of WPS.

Regards,

Anish Thomas

[c sridhar]

The importance of inter pass temperature

To control the mechanical and micro structural properties of weldments, inter pass temperature is just as important as, 

if not more important than, preheat temperature. Yield and ultimate tensile strengths of the weld metal depend greatly 

on inter pass temperature. A high inter pass temperature can reduce weld strength and at the same time result in a 

finer grain structure and improved Charpy V notch-toughness transition temperatures. However, when inter pass

temperatures exceed approximately 250⁰ C, this trend is reversed.  

Minimum inter pass temperature shall help to prevent cracking and a maximum provides required mechanical 

properties. To maintain this balance, the time between passes, base-material thickness, preheat temperature, ambient

conditions and heat input from welding to be considered.

For quenched and tempered steels a maximum inter pass temperature will provide adequate mechanical properties

in the weld metal and HAZ.

The inter pass temperature be maintained "for a distance at least equal to the thickness of the thickest welded part  in all

 directions from the point of welding and measured  20 to 25 mm  from the weld toe.

But, Maximum inter pass temperature control is not always required. AWS  D1.1 does not impose such control.

For CS, and other non ferrous metals. Heat input should be around 2.0 k j/mm

SS do not require preheating. Inter pass temp. should be around 75 to 150 ⁰ C. The total heat input should

be within 1.0 kj/mm.

For DSS, max. temp. should be within 125 ⁰ C or so. Heat input should be with in 0.6 kj/mm or nearest to it.

Sridhar

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From: anish thomas <anish...@gmail.com>

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[Steven Teo]

Good info Sridhar.

 

May i ask what is your preference for choosing preheating temp among the 3 below ?

- As tested,

- AWS D1.1

- Welding consumable maker recommendation ...usually stating "must" be within a range of x to x degC.

 

Other than thickness, CE value, etc. Removing moisture by flame drying is not considered as preheating.

[c sridhar]

  Thanks.

 Welding consumable recommendation is a guideline and could be followed to some extent.

 The effects of the welding process, procedures, and sequence of welding will help to maintain

 inter pass temperatures within the proper range.

 The mechanical and micro structural properties of the weld metal and HAZ will help to consider

 both minimum and maximum inter pass temperature.

 The inter pass temperature should be maintained for through thickness of base metal and 25 mm

 or so  distance away from the weld.

 

 Sridhar

  

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From: Steven Teo <bvs...@yahoo.com.sg>
To: "mateials-w...@googlegroups.com" <material...@googlegroups.com> 

Sent: Monday, 11 November 2013 9:48 AM
Subject: Re: [MW:19243] Inter pass temperature selection criteria.

[c sridhar]