Heat Treat Industry News
January 08, 2010
Influence of Alloying Elements in Steel – Manganese (Part 1)
This blog is the continuation of "Influence of Alloying Elements in Steel: Part 1," which was posted March 4, 2009. You can read that blog here.
From a heat treater’s perspective, the purpose of adding alloying elements to steel is to enhance the material’s response to heat treatment, which in turn results in improvement of the mechanical and physical properties of the steel. Alloying additions are made for one or more of the following reasons:
To increase hardenability
To produce a finer grain size
To help control part distortion
To improve tensile strength without appreciably lowering ductility
To avoid quench cracking
To gain toughness
To achieve better wear resistance
To improve hot hardness
To achieve better corrosion resistance
With this disclaimer in mind, it is time to talk about the element manganese (Mn). We know that the effect of a particular alloying element on either the steelmaking process, the response to heat treatment and the properties achievable depends on the effects of both the element in question and on the (complex) interactions with other elements, either individually or collectively.
The role manganese plays in deoxidation of steel and modification of sulfides presents it is a major alloying element. It has complex interactions with carbon and is used to control inclusions. Manganese is beneficial to surface quality in all carbon ranges with the exception of rimmed steels (< 0.15%C) and is particularly beneficial in high-sulfur steels. Manganese contributes to strength and hardness, but to a lesser degree than carbon. The increase depends on the carbon content – higher-carbon steels being affected more by manganese. Higher manganese in steels lowers ductility and weldability (but to a lesser extent than carbon). Manganese also increases the rate of carbon penetration during carburizing.
Next time, we will look at some of the 50 ways manganese affects steel.
by Daniel H. Herring - January 6, 2010
Daniel H. Herring
dherring@heat-treat-doctor.com
Dan Herring is president of THE HERRING GROUP Inc., which specializes in consulting services (heat treatment and metallurgy) and technical services (industrial education/training and process/equipment assistance. He is also a research associate professor at the Illinois Institute of Technology/Thermal Processing Technology Center.
SOURCE: http://www.industrialheating.com/
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