Monday, September 10, 2018

Re: [MW:28253] preheating


Thanks/Regards,Preheating is the process applied to raise the temperature 
of the parent steel before welding. It is used for the following main reasons:

·         The slower cooling rate encourages hydrogen diffusion from the weld area 

by extending the time period over which it is at elevated temperature 

(particularly the time at temperatures above approximately 100°C) 

at which temperatures hydrogen diffusion rates are significantly higher than at 

ambient temperature. The reduction in hydrogen reduces the risk of cracking.

·         To slow the cooling rate of the weld and the base material, potentially resulting in 

softer weld metal and heat affected zone microstructures with a greater resistance 

to fabrication hydrogen cracking.


C.R.Bhiwandkar
Supreme Megastructures Pvt. Ltd.

Cell No.:-+919867139337



On Sun, Sep 9, 2018 at 3:31 PM Souravbohray <ermechsouravbohray@gmail.com> wrote:
what is use of preheating ?
how can control rate of cooling by preheating ? by apply of heat how cooling rate can be control ?
by preheat hardness increase or decrease?

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