Steel oil problem 1

[bearingsteel]

We have a tank with 11 tons of cold oil (50 grades C) with the cooling speed of 75 grades C/s. Out of 2000 rolls 100Cr6(52.100), only 10-15 rolls have high levels of bainite , aprox 40-60% and harndness of 30-50 HRC. It is possible that the oil is bad or could be another reason of this problem?

 

[racookpe1978]

Of the 2000 rolls, what order did the problems occur, and how "randomly" do they occur. If the problems happen regularly in the first (or last part) of the run of 2000, then gradual contamination or heating of the oil pool is likely. If the problems happen near the beginning, then the pool may not be evenlly "smooth" in a temp profile and some are too cold or only partially cooling until the whole pool gets "stirred up" ..

If the problems are randomly distributed w/r to time of the run, then you've got a steel supply problem of varying steel consistencies, not a heating problem.

If the problem is physically distributed according to where the rolls are stored on the floor or how they are placed in the oven, then you've got a heat creation (oven) geographic problem: some too hot, some parts too cool. On the floor, maybe some rolls are close to a heat source or fan or open door where they are cooling differently. .

 

[redpicker]

I would doubt the oil is "bad", or, more correctly, I doubt it is the source of your problem. Check with your quench oil supplier to see if they will analyze a sample to be sure. It is good practice to have oil samples regularly analyzed and most quench oil suppliers will provide this service at no charge.

As racookpe1978 has mentioned, a little more investigation into the problem can lead to a solution. If only 10-15 out of 2000 are out-of-tolerance, that is better than 99% good, which indicates that the process is capable, you just need to adjust the process controls to eliminate the source of the out-of-tolerance condition. With a better understand of the process (batch or continuous) and your current controls, the internet may be able to help, but a carful review of the process by someone who is close to it (yourself, perhaps) will likely be more productive.

As I said, I doubt the oil is "bad", but if you have doubts, you need to check it out. More likely, it is related to the issues racookpe1987 has brought up.

Good Luck,

rp

 

[bearingsteel]

We already found problems with the cooling speed of the oil but we have to convince those in leadership. This is why i wanted to see other opinions.