Effects of Heat Treatment on Sintered Metals

July 9, 2018

A tightly narrated overview pinned down the main operational components in the powder metallurgical process. At this point, a new opportunity has arisen. It’s a chance to look beyond the manufacturing technique, to view the effects of heat treatment on sintered metals. Do sintered objects bend to the will of a furnace or tempering station? Once the sintering work is complete, there’s often a need for secondary parts-conditioning operations, after all.

Heat Treatment Feasibility 

Before going any further, a swift process review is on the cards. The metal particles have been mixed and injected with additives. The mix was compressed, and then the sintering stage took over at the process endpoint. In point of fact, the sintering work already calls upon heat treatment technology. The compacted powder fuses and forms into a single material part when that transformative thermal load is applied. However, this post is focusing on secondary heat treatment pursuits, not the thermally active sintering operation. So, again, is that post-treatment operation feasible? The answer to that question is definitely, yes, post-process heat treatment techniques can be utilized after the sintering and light machining stage are complete. However, there are a few caveats to beware of during those heat-oriented operations.

Performing Sintering Treatments 

After the component has been compressed and formed, it enters the sintering stage. While it’s true that an intelligently regulated sintering procedure yields hardened parts, the same cannot be said for a poorly managed procedure. If the treated component is to remain hard, not brittle, all remaining pressing lubricants, surface oxides, and combustible vapours need to be eliminated. To assure a perfectly fused material profile, the thermal envelope requires careful management. Likewise, the atmosphere in the sintering equipment must be controlled so that the furnace atmosphere doesn’t cause decarburization. In summation, Temperature levels, timed responses, and properly regulated furnace atmospheres are responsible for consistently hardened sintered metals.

Post-Processing Treatments 

Classed as the heat treatment operations that add or subtract physical and mechanical attributes to a metal part, this essential end-stage operation hardens and toughens sintered components. To control the powder-fused properties, the components are hardened in furnaces and tempered in cooling rooms or quenching stations. Since sintered products incorporate a porous structure, the knowledge that a heat conditioning process can further harden and temper that part is a welcome fact.

Alloying metals and mix compositions are known to impact heat treatment techniques. And those process variables do come into play when a sintered product is the subject workpiece. However, as long as these factors are weighed during the operations, there’s no reason that a sintered part can’t be hardened or otherwise physically altered until it suits a stated application.

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