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Could anyone help me to find information on sulfinert information. It seems to be a passivation technique of stainless steels which bonds an inert silica layer into the surface of the steel? I would like to have information on the type of this treatment (CVD, chemical conversion, ....) and if...

Could anyone tell me if the hydrogen test (N2 + 5% H2 during a few minutes) to control the tightness of a product can degrade material properties?

We have principally flat products made of bearing steels from 6 to 12 mm thick. The parts are fine blanked and heat treated to obtained a hardness of 700-800 HV. The geometries of the different parts are rarely symetric.

Many thanks for your information. Could you give me the reference of the IMA specification concerning the demagnetization level?I do not find it on the web.

MagMike : Concerning our research, we'd like to know when our parts made of bearing steels are "correctly" demagnetized and how measure them (pb of local magnetization in complex geometry despite global demagnetization). The demagnetization is important for us for machining, non destructive...

Could anyone help me to give a physical (idealy quantitative) basis on the evaluation of a demagnetization threshold? We need that the magnetization is low enough not to attract ferrous shavings or filings. Our practical upper limit is 8 Gauss (640 a/m) of residual magnetization. An other...

Could anyone tell me if there is a problem in using nitrile seal in dry atmospher?

We are talking about connecting parts manufacture from bars requiring a high property and the customer could see with a bad eye an irregular aspect. The EP has also the function of increasing the corrosion resistance.

I have not yet any information about its history. But we have carried out several tests of decontamination in nitric bath without result

We have pb with the surface of some parts made in 316L after an electrolytic polishing. The microstrucutre examination reveals an large amount of ferrite delta and we wonder if it could explain the aspect of the surface (like a presence of a white layer)

I would like to complete this thread with new measurements of the residual stress : the values are more likely up to 700-800 MPa in tension in the direction of the thickness (on an approximately 70 µm depth) all along the martensitic zone whereas we have -500MPa on the faces. It is interesting...

Helical compression spring I didn't calculate the stresses It is for cylcic use Dimensions : wire Ø = 4.5 mm / spring Ø ext = 22.5 mm Total length in free condition = 46.8 mm Total length in contiguous spir = 32.35 mm Spir number = 6.69 Frequency utilisation = 20 Hz Material : oil quenched...

We have problems to understand some spring fracture facies. It works under compression, with probably some times flexion stress. We are interested in web sites which show fracture facies linked with explications, like initiating, propagation and final break

Thank you for your advices. We use these kind of products either between operations and on the final parts. But the problems occur at subcontractors or on raw materials.... That's why we need a mean to confimr or not the presence of rust and a curating method when the rust presnce is confimed.

No decarburation can be seen on the micrography, only a fine analysis ("microsonde") could put a partial decarburation in evidence. In fact, I beleived that the high frequency treatment was short enough to avoid any decarburation problems in depth. But to complete the description of our...

The stress pattern is measured by diffraction and the matter is removed by electrolytic method from the surface to 50µm in a radius where we have sometimes problems of cracks.

The problem is general : parts obtained by fine blanking, laser cutting, machining.... The material is carbon steels or HLE (high elastic limit),... The environnement is "normal" environnement of stockage : ambiant temperature inside

We are frequently questionned about red coloration of parts : is it rust or only a coloration of a residual product like oil or temporary protection or anything else? Today, we examine the parts with a magnifying device to see if the "rust" begins to dig the metal Does anybone know an easy...

I'm going to try to respond to your questions .... The 3 zones are heat treated in 2 times but these zones are sufficiently distant to avoid any problem of thermal affected zone. The material of the part is 65Cr3. And the treatment consists in a high frequency treatment with an inductor in...

I agree with your point... That's why we are very suprised by the stress field : a tensile field (+200MPa) close to the surface 0-5µm and a low compressive (-50 MPa) fied underneath.