Stress Corrosion Test

[Olcay]

Situation:
We are heat treating a part made of sheet metal 50CrV4 used as clamp. There is a test for stress corrosion as : Put the parts under stress, in a 0,9% HCl solution, and they must stand at least 8 minutes before broken.

Problem:
We could not solve which parameters of hardening and tempering process will effect the results of this test.

 

[gdodd]

How many different microstructure types can be obtained by heat treating the part?
As a rule austenitic stainless steels are susceptible to stress corrosion cracking whereas ferritic and duplex stainless are not. An added danger is that ferritic and martensitic stainless steels can fail by hydrogen embrittlement (a possibility in an acidified solution).

Good luck

 

[Olcay]

Dear Gdodd,

50CrV4 is a kind of spring steel. We are hardening and tempering the parts to 510-550 HV. We do not know which parameters of heat treatment (eg. temperature/time/oil/tempering temperature...) is effecting the results of this test. Lets suppose will it help to lengthen the tempering time? or what? Our furnaces are chamber type Ipsen furnaces and endogas is used as atmosphere controll. Does endogas has any effect on test results.

Thanks in advance for your kind interest..
Olcay

 

[gdodd]

If you are having trouble passing the stress corrosion test with a quenched and tempered treatment try austempering the part. I am not familiar with the composition of the material however austempering can produce a tougher less brittle part than quench and temper. Check with a contract heat treater in your area.
Good Luck