Hi aratron,
Sorry for late at reply, but last days I have been very busy preparing and answering my last thread about “BRUSHING AND POLISHING damaged bezels†(now a Sticky Thread)
Firstly, many thanks for your kind comments.
You are very modest. I see you are not a noob on this matter!
Your questions are very timely and give idea of your knowledge about the SS.
You are asking for some interesting things.
In fact, I thought it was not necessary in this Thread speak about this SS 440 matter, But, by your post, I have seen I was wrong!
Really it is interesting to clarify this question to not have misunderstanding in the future.
Let’s start from the chemical composition:
SS 440
Ni - 0%
Cr- 16-18%
Mo- < 0,75%
Mn- <1%
P- < 0,04%
S- <0,03%
Si- < 1%
C- 0,65-1,20% (depending on grade)
Fe- the rest
As you can see it is a SS without Ni. It is “stainless†just for the Cr content.
Its C content is higher than 316 series.
As usually, this chemical composition gives it especial physical properties.
In comparison with SS 316 series, we can find:
- SS 440 is a SS martensitic type. SS 316 is an austenitic type.
- SS 440 is magnetic. SS 316 are no magnetic.
- SS 440 can be heat treated to become very very hard.
- SS 440 is harder in annealed condition and a lot harder after heat treatment.
- SS 440 annealed is less easy for machining, but after heat treatment it will be almost impossible for machining.
- SS 440 is “white†and shiny. Like a chromed steel by electrolysis.
- SS 440 has less corrosion resistant properties than SS 316 series.
The main application of SS 440 is in cutting instruments, valves seat, rolling elements bearings, surgical instruments, chisels, high grade knifes, scissors, swords, daggers…
SS 440 is a very good and hard Steel and it allows heat hardening treatments, it has a very “white†and shiny colour (like a chromed steel by electrolysis), it is a medium grade SS machining performance and corrosion resistant. It is used for cutting instruments and items which need high hardness.
The 440 is not a SS for high quality watches due to corrosion resistance, machining performance, magnetic properties and colour.
The price of a SS 440 is cheaper than the price of a SS 316 series, due to it has not Ni in its chemical composition.
I hope these explanations answer your questions.
But there is a question without reply:
Since the SS 440 is cheaper than SS 316, why some (bad) dealers say that their replicas are made of SS 440?
I have never definitive reply for this question!! I have some thoughts or ideas but I’m not sure.
- Because people think (and perhaps those dealers) that a higher number means more quality. The higher the number the higher the quality.
- Because people think (and perhaps those dealers) that a higher hardness means better quality.
- Because the bad replicas are made with low grade Steel chromed by electrolysis and the SS440 is similar in colour or, even, with a very low-grade SS cheaper than SS 440. Then, the dealers say that their replicas are made of SS 440 (?), but they are really made of very low grade steel.
Whatever the dealers motives may have been, they are using the name of SS 440 on their profits, and it is clear that there are not replicas made of SS 440.
I hope all is clear now