Hi
The company crack must be checked under microscope to identify is it quench crack.
Quench crack passes through grain boundaries.
The crack zone is high stress area due to bending process. So there is a possibility for crack while bending it. It must be hot forged to avoid crack for this...
My opinions are as below:
Low carbon steel - C% <0.3
Medium Carbon steel C%- 0.3-0.6
High Carbon steel C% -0.6-0.99
L80 (API 5CT) type-1 will be comming under medium carbon steel and L80 type-1 is equivalent to SAE 4140. Because both need oil quenching in heat treatment process quenching and...
Generally the high hardness material will have very small amount of plastic deformation during impact load, so the impact test and results are not much widely available or useful for high hardness material.
To come to the conclusion, parts are not heat treated properly, you have to mention the specification given to the supplier.
The hardness is more related to the severity of quenching.
More sever quenching --> More Martensite--> High Hardness
Less Sever Quenching--> Less Martensite--> Less...
API 5CT page 9- chapter 4.1.6 says that The hardness numbers and/or mean hardness numbers obtained shall comply with the requirements in Table C.5 or Table E.5.
So if the supplier mentioned several surface hardness value then it can be accepted if the average is confirms to max HRc-23.
Another...
My opinion is to eliminate the root cause from casting ( Material) just compare the microstructure of your supplier difficult to machine casting and competitor casting in thin and thick sections.
If you find same microstructure then its something related to your machining process.
the following...
The chemistry is the basic building block for getting microstructure and hardness.
Microstructure and hardness is linked to each other very much.
The chemistry can give different microstructure (hardness) based on heat treatment process.
Surface Hardness:
Quenching and tempered SAE 4130 -...
you need to do the tempering after quenching with in 1.5hrs ( best) to avoid cracks or distortion of the part due to stress gained in the quenching process.
Also tempering break the martensite needle structure.
Tempering & normalizing both relieve the stress, so there is no need to tempered it...
Hello
My opinion is, its not possible to change the distortion with press for 7075-T6. the distortion must be controlled in quenching and machining process.
The machining might have done with compensation for distortion and appropriate machining technique. If you want to releive the stress then...
I share my opinion from metallurgical point of view:
D2 material is high carbon low alloy steel. High carbon gives high hardness and wear resistance when quenched from austunitie zone. When it get very high amount of stress from cooling & high martensite % then it will tend to break.
soft...
Hello davyjacob
I am not sure whether you are doing Selective Inhibition Sintering (SIS) which use salt. what is the prupose of the salt? Are you making ceramic coating over the metal powder or salt will be dissolved in solvent to create porous structure.
In case if you planning to use the...
Hello
I would like to share my opinion as below:
The compacting pressure must be decided based on the density of metal required in the final part. Also based on the method of pressing, you can change the pressure eg: die pressing, hot isosatic, cold isostatic etc.
If you have decided the...
I share my opinion as below:
1. There is nothing like environmental aging for steel grade 4130.
2. High hardness can be possible due to following reason:
1. quenched with high severity instead of required: wrong HT cycle followed or part wrongly mixed with other part HT cycle for making full...
