Heat treatment of 17-4PH separately cast specimens

[absaul02]

Hi,

I'm currently making a development about 17-4PH investment casting but I have some doubts about separately cast specimens for tensile and impact tests. Can I heat treated these specimens (diameter of 6.35 mm) in the same charge of pieces of castings? or do i need heat treated the separately cast specimens in different charge? The pieces of casting have a thickness of 2 1/2 inches and a weight of 35 kg.

another question is do i need using an atmosphere such as vacuum, argon or nitrogen? or Can i use a furnace without controlled atmosphere for this material?

Regards.

 

[mfgenggear]

OP
it depends, if it is finished surface or if there is stock removal, for machining.
even if not required follow the AMS 2759/3
procedures. finished surface in a Vacuum, or inert atmosphere. prevent oxidation. precipitation harden. run with specimens for testing.

 

[EdStainless]

We used to do both.
HT some samples in the lab and some with the parts.
Served to verify both the material and the HT.
And nitrogen is not an inert atmosphere.
The alloy will absorb some at the annealing temp and it mess with the phase balance.

 

[absaul02]

OP
it depends, if it is finished surface or if there is stock removal, for machining.
even if not required follow the AMS 2759/3
procedures. finished surface in a Vacuum, or inert atmosphere. prevent oxidation. precipitation harden. run with specimens for testing.

We used to do both.
HT some samples in the lab and some with the parts.
Served to verify both the material and the HT.
And nitrogen is not an inert atmosphere.
The alloy will absorb some at the annealing temp and it mess with the phase balance.

Greetings.

Thank you for your reply.

I would like to express my concern regarding the necessity of verifying the mechanical properties of the casting. It is of the utmost importance that these tests be performed separately from the part. However, the test pieces are too small in relation to the casting to be placed in the same furnace. This could result in an over-treatment, which would incur an excessive cost if the heat treatment is done separately. Are there any alternative options for the heat treatment?

I have reviewed the standard procedure, and I have found that it is possible to order a square "cupon" that will be machined after the heat treatment for the test. This will reduce the probability of over-treatment and allow the casting and the "cupon" to be placed in the same furnace.

What is your professional opinion on the feasibility of this approach?

 

[mfgenggear]

Greetings.

Thank you for your reply.

I would like to express my concern regarding the necessity of verifying the mechanical properties of the casting. It is of the utmost importance that these tests be performed separately from the part. However, the test pieces are too small in relation to the casting to be placed in the same furnace. This could result in an over-treatment, which would incur an excessive cost if the heat treatment is done separately. Are there any alternative options for the heat treatment?

I have reviewed the standard procedure, and I have found that it is possible to order a square "cupon" that will be machined after the heat treatment for the test. This will reduce the probability of over-treatment and allow the casting and the "cupon" to be placed in the same furnace.

What is your professional opinion on the feasibility of this approach?

Sure , the other option and expensive is to scrap a part. Machine test sample from it.
That needs to be quoted in . However how big and expensive?

 

[EdStainless]

OK, test pieces in with parts will see longer times at temp, but the temps are the same.
Or you can strap the samples to an actual piece so that they heat more slowly.
Times are not super critical.

 

[absaul02]

OK, test pieces in with parts will see longer times at temp, but the temps are the same.
Or you can strap the samples to an actual piece so that they heat more slowly.
Times are not super critical.View attachment 10777

Hi.

The manufacturer told me that he has to heat treat the tensile and impact test specimens at a different load than the castings because the specimens have smaller dimensions and could be over-treated. However, heat treating the specimens at a different load costs $5700 (only 4 x 6.35 mm diameter calibrated tensile specimens and 2 x 10 x 10 x 55 mm impact specimens) and seems to me to be an excessive cost. To avoid this cost I have thought of heat treating these specimens in the same load as the castings or requesting a coupon that has the same dimensions as the casting (I attach a picture with the dimensions). However the manufacturer told me that machining the specimens from a coupon after heat treatment can induce stresses in the specimens and affect the expected results. Because of this I don't know what to do anymore. I don't want to pay the $6000 dollars since this project is for a company. I understand that the cost is high because they are going to be heat treated in a vacuum but it is still a very high cost for a simple specimen. Can you give me some suggestions based on your experience? Another doubt, should the stainless steel be treated in a vacuum furnace or controlled atmosphere? I made this request because the part is for a gas turbine, but if it is not mandatory for this material I could also quote without vacuum treating the parts and reduce the cost. Thank you for your comments.

 

[RolMec]

in my field all of the specimen are machined, and on a personal note I am not too fond of nono partners who put all the signs pointing their way.

 

[mfgenggear]

Hi.

The manufacturer told me that he has to heat treat the tensile and impact test specimens at a different load than the castings because the specimens have smaller dimensions and could be over-treated. However, heat treating the specimens at a different load costs $5700 (only 4 x 6.35 mm diameter calibrated tensile specimens and 2 x 10 x 10 x 55 mm impact specimens) and seems to me to be an excessive cost. To avoid this cost I have thought of heat treating these specimens in the same load as the castings or requesting a coupon that has the same dimensions as the casting (I attach a picture with the dimensions). However the manufacturer told me that machining the specimens from a coupon after heat treatment can induce stresses in the specimens and affect the expected results. Because of this I don't know what to do anymore. I don't want to pay the $6000 dollars since this project is for a company. I understand that the cost is high because they are going to be heat treated in a vacuum but it is still a very high cost for a simple specimen. Can you give me some suggestions based on your experience? Another doubt, should the stainless steel be treated in a vacuum furnace or controlled atmosphere? I made this request because the part is for a gas turbine, but if it is not mandatory for this material I could also quote without vacuum treating the parts and reduce the cost. Thank you for your comments.
View attachment 10839

Op
That is ridiculous. Find an other supplier.
Get 3 quotes. And the part about stressing the coupons is nonsense. What is the wall thickness of the casting. Plus what is the time and temperature. , what pops in my head one hour per inch.

 

[absaul02]

Op
That is ridiculous. Find an other supplier.
Get 3 quotes. And the part about stressing the coupons is nonsense. What is the wall thickness of the casting. Plus what is the time and temperature. , what pops in my head one hour per inch.

Thank you for your comments. Attached is a screenshot of the heat treatments for 17-4PH cast. I need specimens in solution condition (because I require my castings in this condition for machining) and H925 condition to know how they respond to the ageing heat treatment. The thickness of my castings is about 2.2 inches with a weight of 35 kg. The manufacturer casts my specimens already with final dimensions (6.35 mm gauge diameter and 10x10x55 mm), he does not use coupons to machine the specimens from them. I proposed to use coupons to heat treat them in the same load as my castings and save $5700, but he says it is better to heat treat the specimens in another load. Regards.

 

[EdStainless]

1. HT the coupons in the same production furnace is nuts. This what calibrated lab furnaces are for.
2. The stress argument is nuts. You anneal and machine, then age. The aging treatment is an an effective stress relief.
Of course using H900 or 925, or even 950 is very risky. The tensile strength will vary a lot from batch to batch. Minor differences in chemistry, annealing temp, and aging temp will all effect properties. That on the toughness is very low.

 

[mfgenggear]

Thank you for your comments. Attached is a screenshot of the heat treatments for 17-4PH cast. I need specimens in solution condition (because I require my castings in this condition for machining) and H925 condition to know how they respond to the ageing heat treatment. The thickness of my castings is about 2.2 inches with a weight of 35 kg. The manufacturer casts my specimens already with final dimensions (6.35 mm gauge diameter and 10x10x55 mm), he does not use coupons to machine the specimens from them. I proposed to use coupons to heat treat them in the same load as my castings and save $5700, but he says it is better to heat treat the specimens in another load. Regards.

H925 according to the spec is equivalent 38-45 Hrc , this is the approach I would take, make the test specimen same as the wall thickness, after heat treat machine to correct size for testing. that hardness is easily machined with out compromising. run the parts with test specimens.
discuss with a heat treater who is willing to play ball. have a face to face discussion with who is in charge . and willing to follow up in working with you. what country are you in. I worked with many heat treaters in the USA , that could recommend

 

[absaul02]

H925 according to the spec is equivalent 38-45 Hrc , this is the approach I would take, make the test specimen same as the wall thickness, after heat treat machine to correct size for testing. that hardness is easily machined with out compromising. run the parts with test specimens.
discuss with a heat treater who is willing to play ball. have a face to face discussion with who is in charge . and willing to follow up in working with you. what country are you in. I worked with many heat treaters in the USA , that could recommend

Hi.

Thanks you every much for your response. I'm based in Mexico, and I would really appreciate it if you happen to know any reliable heat treatment providers here that you could recommend. I'm currently evaluating different options and your input would be very helpful.

Thanks again for support.

1. HT the coupons in the same production furnace is nuts. This what calibrated lab furnaces are for.
2. The stress argument is nuts. You anneal and machine, then age. The aging treatment is an an effective stress relief.
Of course using H900 or 925, or even 950 is very risky. The tensile strength will vary a lot from batch to batch. Minor differences in chemistry, annealing temp, and aging temp will all effect properties. That on the toughness is very low.
View attachment 10856

Thank you for your comments. Just to clarify, the heat treatment will not be performed in a production furnace.It will be done by an external company that operates vacuum furnaces, Tih process is being carried out specifically for a first article inspection.

 

[mfgenggear]

OP
I have no recommendations in mexico.