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

 

[swall]

What is the carbon content of the steel and what was the quenchant?

 

[arunmrao]

How low is the carbon and what other alloying elements are there in the steel? In what medium was the steel quenched and finally the section thickness?

Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)

 

[leizhou]

The material is 0.13% carbon, quench in water, tempered at 650C

 

[leizhou]

The section is 1 inch cube, tempering for 1hour,
Mn1.3, Si0.25,Cr/Ni0.14,Mo0.2

 

[swall]

You do not have sufficient carbon content to form any appreciable martensite.

 

[Metalmeister]

Fine grained ferrite with isolated grains of pearlite. I don't believe that a steel of that lean an alloy composition and low carbon content can achieve any martensite. The nose of the CCT curve that you must pass during quenching to get martensite is probably off the graph.

 

[dbooker630]

SAE 1513 is a carburizing grade of steel. Forged camshafts is one application I remember. The microstructure you report is typical for this material.

 

[leizhou]

Thanks for everyone!

In fact, I had 3 samples, which are same materials.

I had them for different heat treatment. Quenching, quenching_tempering at 580, and Q+T at 650.

The just quenched one shows there are some martensite formed.

For 580C I think it is the tempered martensite structure.

But for 650C, the pearlite come, and I do not understood.

Thanks again

 

[leizhou]

The material is a ASTM 694, F65. used in flange and pipe.

 

[dbooker630]

Can you post some microstructure photos? At 650C you are approaching a spheroidizing treatment, which might explain what you are seeing.

 

[TVP]

I agree with dbooker630-- 650 C for such a low carbon steel will likely result in spheroidizing of any carbides that may be present.

 

[leizhou]

I hav attached some micrograph of 650.

If you can not access to it, please let me know your emails please.

Thanks

Also, as I am a graduate working in the metalurgy area. Is there any good way to ahieve knowlage and experience like you guys as fast as possible?

 

[dbooker630]

Can you save the file in an earlier version of PowerPoint? I don't have Office 2007.

As far as your second question, there is no shortcut. Thirty years ago I was in your shoes, the best thing I can say is to work with metallurgists that do have the experience. Not everything is in the textbooks.

 

[TVP]

leizhou,

Can you confirm the etchant and the magnification of the image? I believe this is spheroidized carbides in a ferritic matrix, but the magnification appears to be quite low. Can you obtain higher magnification?

 

[leizhou]

Thanks again.

I use to think this is a spheroidized phase, but I do not think the time 1 hour is enough for it. Also, a testhouse call bodycote say that is pearlite.

I really wish to learn from other metallurgists but I am the only "metallurgist" as my company is a design based.

I have attached the file in 2003 version.

Thanks

 

[dbooker630]

leizhou,

I just downloaded a PPTX viewer and I agree with TVP. If you can get a 500X shot we can confirm the structure for you.

 

[leizhou]

this image is under x400, I will try further. that takes me time.

Thanks

 

[Robertmet]

If you were able to get any martensite after quench it would become tempered martensite at the 650 C temper. Yes it would take more than 1 hour to spheroidize it. Hypoeutectoid steels have a mixed ferrite/pearlite structure .After HT , depending on the conditions you can get interesting structures .The structure below is a hypoeutectiod steel [ Japanese sword] with ferrite grains surrounding a grain [originally pearlite] of pearlite at the edges and martensite in the center.

 

[leizhou]

It is not quite possiblr for me to have a higher magnification now. However, I have got one more micrographs. (580C heep for 4hrs)

Can anyone confirm that it is ferrite + pearlite for the 580C one?

Thanks