I am looking for studies related to austenization soaking times and ways to reduce the time to achieve full dissolution of carbides as well as not to obtain austenite grain growth. Grain growth will take place with increasing soaking time. I am looking for any studies that discuss about ways to reduce the soaking time to obtain full carbide dissolution as well as stay in the optimum austenite grain size range. The steels cast have carbon in the hyper-eutectoid range. i.e. greater than 0.78% C, in about 0.88% C. I would highly appreciate feedback from experts.
Dear Muhammd,
soaking time depends on the how much carbide is there. Example, Holding of railway switch components 2 h at quenching temperature of 1050–1100°C is sufficient for obtaining uniform distribution of manganese and high mechanical properties.
1 inch of cast iron 1.5 hour.
it depends on thickness and how much carbide is there to form. Holding the material (Soaking) at the temperature for longer time. try with TTT diagram and heat treatment.
Soaking time at hardening temperature should be long enough to transform homogenous austenite structure. Soaking time increases with increase in section thickness and the amount of alloying element being treated. Delay in Quenching: After soaking, the steel is immediately quenched. Delay in quenching may reduce hardness due to partial transformation of austenite.
Hope it work out for you.
Just use the sorce
https://books.google.com.et/books?id=O9VpRve60tMC&pg=PA238&lpg=PA238&dq=What+is+the+optimum+austenization+hold/soak+time+for+cast+structures?&source=bl&ots=AXOnql-7NP&sig=ACfU3U2_aOVnxabuFLrf93Wx-DzWscpnAw&hl=en&sa=X&ved=2ahUKEwjGm5OGjdPlAhXqDWMBHUe3ANwQ6AEwDXoECAkQAQ#v=onepage&q=What%20is%20the%20optimum%20austenization%20hold%2Fsoak%20time%20for%20cast%20structures%3F&f=false
Ashish
First, I recommend to check if you really need full austenitization. Normally, hyper-eutectoid steels are heated into two-phase austenite-carbide temperature zone and then are quenched to obtain carbide/martensite structure. You actually need full austenitization only in the case of normalizing.
Second, the soaking time depends on a wall thickness of the heat-treated part. Normally, for wall thinner than 5 mm, the minimal soaking time is 18 min; 5-15 mm - 35 min; 25-40 mm - 40 min, etc. The reason for that is to achieve a homogeneous temperature distribution over the whole thickness of the heated part. On the other hand, the part with strongly different wall thicknesses may be problematic form the point of view of the homogeneity of the post-treatment microstructure.
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