Molybdenum

[Cheese789]

My casting supplier has asked me to reduce or take out the molybdeum out of my castings, due to increasing costs of the material. What effect would this have on the properties of the castings. The castings are used in a briquette press.

 

[gieter]

Please be more specific on the alloy.

 

[EdStainless]

I presume that these are tool steels. Give us a composition.

My gut feeling is that if the alloy has been working for you I would be reluctant to change. A small materials cost savings can cause huge service issues latter.

Yes, Mo prices have gotten out of hand. Last week technical grade Mo oxide was selling for $34/lb. Two years ago it was under $4/lb. On the other hand, some of the Mo producers have said that they expect the prices to drop sharply back to the $10-15/lb range.

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Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[Spiralis]

In a paper made by SINTEF in Norway in the 1990's about corrosion resistance for stainless steels, this is mentioned about molybdenium:

"Increasing amount of molybdenium will increase the corrosion resistance of corrosion forms like pitting and crevice. The element also increases the strength of the passivation layer of a stainless steel in chloride environment."

I have translated the text from Norwegian.

 

[mcguire]

Yes, we do need to know the alloy in question because the role of moly changes with the alloy system. It is not irreplacable, however, so be specific about the alloy you use and to what purpose you apply it.

 

[arunmrao]

I make a low alloy steel casting containing 0.3-0.4% Moly. This is used in WQ &T conditions. The final hardness being 430 -450 BHN.

Now the cost contribution of Moly in this alloy is 30% of the saselling price. This is too high and every order I process I lose money. I too have made a request to compensate for Mo price or alter the alloy.

I know customers have seriously been considering use of CF8 instead of CF8M purely for commercial reasons.

My customer in Europe negotiates prices for his castings on a day to day basis due to spiralling Moly prices. It is just shor cut to insanity.

 

[EdStainless]

We have been selling tubing on a 'plus surcharge' basis since Nov. 03. We saw supplies tightening and knew that prices would rise. The surcharges are linked to publicly available price information. Customers will pay surcharges. They may wish for 'something for nothing', but they know that in the long run it is the only option for a stable and reliable supply.
We have been through this with Ni, Co and Cr over the years. If your customers don't want a long term relationship with you and don't believe what is in the news then there isn't much that you can do for them.
When we buy SS strip it is 'price in effect + surcharge', the base price is the one in effect at time of shippment. The surcharge is fixed 2 months before shippment.
The quotes for Ni alloys have no surcharge, but they are only valid for 24 hours.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[TVP]

EdStainless,

Wow, I had no idea that the situation with Ni alloys was so bad that price quotes are now only valid for 24 hours at a time. Thanks for the perspective.

 

[rd400guy]

Cheese789-
If I understand correctly, your supplier is asking you to spec less moly in the castings he's supplying you? From an end user standpoint, if he's giving you Mo and not charging you for it, you're lucky. If he hasn't caught on to the surcharge mentality, he probably won't be in business very much longer, especially if he's making moly grades. In other words, I'm surprised you're not already paying for the increase in alloy costs.

In terms of what decreasing or eliminating the moly (due to cost) will do to the properties of the castings, the short answer is: it's there for a reason, don't change it.

For best results, please give us the alloy composition (or designation) and properties you require (hardness, yield strength, etc.). If it's a stainless (CF8 vs. CF8M) type casting, then you'll lose some corrosion resistance, and I'm sure EdStainless could go more into effects of moly on corrosion resistance. Since you mentioned a briquette press, I'm imagining it might be either a tool steel or some other hardenable Mo containing alloy, in which case decreasing moly content will have detrimental effects on hardenability, wear resistance, and may increase tendency for temper embrittlement (in thick section castings).

But like I said, for best results, we need more info.