Larsen-Miller Parameter and Hollomon Parameter 1

[vpkhati]

Hello everyone,

I have a doubt and confusion, Please explain me why do we use LMP (Larsen-Miller Parameter) and HP (Hollomon Parameter), and do we use it only for 2 1/2 Cr - 1 Mo. materials (is it because we are using API - 934 A) ..?

WHAT is the use and basis of these parameters.. please explain me..??

If anyone have any software or excel sheet , please share it. I will be very gratefull..!!

Thanks.

 

[metengr]

The LMP and HP are parametric equations that can extrapolate the stress rupture time based on two of three known parameters - stress and temperature. These are equations based on an assumed thermal activation processes that causes creep rupture in metals, so they are very useful equations to predict how long a material in elevated temperature service will last before rupture.

These equations can be used on both carbon and low alloy steels that are subject to creep conditions in service. There is plenty of technical literature on this subject, and I have only provided a general overview.

 

[vpkhati]

Metengr,

thank you very much for your explaination.

Could suggest me some good literarure were I cxan read about theses two parameters in detail.

 

[metengr]

http://www.google.com/search?hl=en&...l18827l0l41l39l5l16l1l0l469l4862l0.4.7.5.2l18

The Hollomon parameter evaluates the response of a metal to temperaing or post weld heat treatment using the same concept as the LM parameter;

http://www.google.com/search?hl=en&...pl=6609l8046l0l8l4l0l0l0l0l359l1108l0.1.1.2l4