Italian powder producer POMETON has launched a new high performance steel powder that uses lower amounts of alloying elements, offers excellent hardenability and versatility. This, claims the company, enhances PM part production and reduces overall production costs.
A group of new high strength and cost effective PM steels has been generated by mixing selected combinations of alloying elements (e.g Cr, Mo, Ni, Cu, Mn) in different and predetermined concentrations.
The main purpose was achieving an optimum balance between compressibility, hardenability and properties. The Fe-based powders used served as a basis for preparing blends leading to a range of microstructures after sintering and controlled cooling.
The PM steels presented in this work have a chemical composition within the following limits in wt%: (0.5-2.0)Cr, (0.5-1.5)Mo, (0.4-2.0)Ni, (0.1-0.5)Mn, (0-1.0)Cu, (up to 0.75)C, Fe-balance.
For identification in this work “ECOSINT A” corresponds to a lean material without Cu while materials B and C additionally contain defined concentrations of Ni and Cu for obtaining blends B(= A + xNi), C(= A + xNi + Cu).
With the powder formulation presented here POMETON addresses this issue developing novel PM steels of enhanced hardenability aiming at offering PM parts producers opportunities for obtaining the benefits of sinter hardening while gaining further processing economy through the use of slower and normal cooling rates.
The chemical composition and alloying method of this newly developed Fe based powder have been tailored to render the critical cooling rate, according to the experimentally determined CCT diagrams, as low as 0.45ºC/s.
After sintering at 1120ºC and cooling at 0.45ºC/s the microstructure at the geometrical centre of a cylinder weighing 135 grams is fully martensite, thus indicating the important hardenability and depth of hardness corresponding to these PM steels.
A homogeneous microstructure and a constant hardness profile were characteristic of discs and rings.
High temperature sintering allows obtaining materials within the range of the highest tensile strength available for PM steel.
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