Tempering of low carbon steel

[leizhou]

I have got a quench and tempered low carbon steel. The microstructure like pearlite + ferrite. Shouldn't it be tempered martensite?

Can someone provide me some useful information about quench and tempering microstructure?

thx

 

[dbooker630]

leizhou,

It is difficult to tell from the photomicrograph. It could be highly tempered martensite but more resolution is needed.

 

[Metalmeister]

Based on CCT curves I looked at, you can't cool a plain carbon steel with 0.13% C fast enough to get martensite. The first micro is over etched, the second micro is under etched. Higher mag won't help, but could confuse. You should be able to discern microstructure at 100x. You must be working with BodyCote out of Chicago area.

 

[TVP]

I disagree with Metalmeister that higher magnification won't help, but it is dependent upon having a properly prepared sample, meaning well polished, uniformly etched, appropriate lighting, correct focus on microscope/camera, etc. None of these items appears to be correct for the second image.

 

[UconnMaterials]

leizhou,

Hello. What is the etchant you are using? Also, are you aware that Mn is austenite stabilizer? Perhaps with this carburdizing alloy you cannot form martensite using water as a quenching agent. What is the Ms Temperature for this alloy? Maybe it's below room temperature.

About the microstructure you presented. You have to be careful with ductile materials when polishing. It's very easy to generate polishing artifacts. Also, please when you present a micrograph put in a marker for scale.

Best Regards

 

[leizhou]

As a lot of post say the bad quanlity of the images.

I have retake the microgaphs this time by myself, please have a look again I think it is much clearer!

The scale bar is not working at the moment.

Thanks

This is the 580C one

 

[leizhou]

This is the 650C one