Not logged inAmerican Welding Society Forum
Forum AWS Website Help Search Login
Up Topic Welding Industry / Technical Discussions / who knows the method of calculating preheat temperature?
- - By edisonwang (*) Date 01-29-2014 12:47 Edited 01-30-2014 07:48
i saw there are two methods how to calculate the temperature of preheat of base metal in a thesis,they a A.W.S method and seferain method .we know before a base metal(carbon steel and alloy steel) welded ,we need to calculate the equivalent carbon content(CE) and Cold Crack Sensitivity （Pc） so that we can determine if the base metal was needed to preheat , because it dont have expatiation so i cant know two method ,who knows them,pls introduce to me ,ths
Parent - - By welderbrent (*****) Date 01-29-2014 18:39
Re-heat of what?  Are we talking low hydrogen welding electrodes?  Are we talking about...??? 

At least for myself, a little more information would be good.

Have a Great Day,  Brent
Parent - - By Superflux (****) Date 01-29-2014 18:58 Edited 01-29-2014 19:37
Edison,
Can you maybe give some more clues to these articles/papers you are referring too?
There might be a translation error here and PRE-HEAT is perhaps what is requested.
Parent - By welderbrent (*****) Date 01-29-2014 21:04
I was wondering about that too.  Thought I'd wait until we got something more.

Have a Great Day,  Brent
Parent - By edisonwang (*) Date 01-30-2014 07:54
sorry . i am misspelling the "preheat" and i cant provide enough information in my question ,but i reedit it .
Parent - - By ctacker (****) Date 01-30-2014 02:43
http://dc107.4shared.com/doc/V8hvaZjV/preview.html
See if section 8.4  is what you are looking for.
Parent - By edisonwang (*) Date 01-30-2014 07:55 Edited 01-30-2014 08:00
ths . maybe it is .but i read the contents  i cant read the details of the date
Parent - - By Tyrone (***) Date 01-30-2014 12:57
Hi Edisonwang,
I can't open your link (security block), but I can give you pointers.

There are two methods for calculating preheat of base metals.

a) HAZ Hardness Method.  Based on the assumption that cracking will not occur, in the HAZ,  if the hardness of the HAZ is kept below a critical value. Also known as the Isothermal Trasformation Method.  Minimizing the HAZ hardness is achieved by controlling the cooling rate. The critical cooling rate for a given hardness can be related to the carbon equivalent of the steel.  From the critical cooling rate, a minimum preheat temperature can be calculated.  Its main value is in determining the minimum heat input (and hence minimum weld size that prevents excessive hardening).    

b) Hydrogen Control Method.  Based on the assumption that cracking will not occur if the amount of hydrogen remaining in the joint after it has cooled to 120˚F does not exceed a critical value.  Also known as the Temperature Control Method.  This method is most widely used since the inputs to the calculations are readily available.

Either method is acceptable but I think the Hydrogen Control Method is quicker and a lot cheaper to perform.  There are a few different tools to calculate the Hydrogen Control Method, here are some:  AWS,  Canadian Welding Bureau (CWB) Calculator, The Welding Institiute (UK), Lincoln Electric Preheat Calculator....

Good luck
Tyrone
Parent - - By paresh Date 11-27-2018 01:56
Can you send the link of this calculator
Parent - By Mayur (*) Date 11-27-2018 06:15
Please discuss....I can give you.:cool::cool::cool::cool::yell:
Parent - By Mayur (*) Date 11-27-2018 06:16
I do have some literatures...AWS D1.1
Parent - By Think Positive (*) Date 01-30-2014 13:47
The equation for calculating CE is published in AWS Metallurgy of Welding Vol. 2.
- By 803056 (*****) Date 01-30-2014 21:47
I use the method described in AWS D1.1:2010 Annex I. There are several steps:

1)   Hydrogen control H1 < 5 ml [H] / 100 g of deposit, H2 < 10 ml [H] / 100 g of deposit, or no hydrogen control

2)   Ceq = 5B + C + Cr/20 + Cu/20 + Mn/20 + Mo/15 + Ni/60 + Si/30 + V/10

3) Susceptibility Index Grouping based on Ceq and hydrogen control  (from table)

4) Degree of restraint: Low Medium, or High

5) Preheat temperature - (from table)

One does not need to know the specification, only the chemistry

Best regards - Al
Up Topic Welding Industry / Technical Discussions / who knows the method of calculating preheat temperature?

Powered by mwForum 2.29.2 © 1999-2013 Markus Wichitill