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Metallurgy/Gravity Die Casting

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Question
Sometime back, I had asked about Gravity Die casting and heat treatment process of LM 11 aluminium alloy to achieve tensile strength of min 310Mpa, Elongation of min 9% and Hardness of min VPN 100 and you have also suggested solutioning and aging cycles.

We have the following problems:

1) Even though we have achieved the hardness, we are unable to achieve the tensile strength and elongation to the required levels.(We did heat treatment as follows: Solutioning at 530* C for 20 hrs and quenching in water within 15 sec. Aging at 170* C for 20 hrs and cooling at room temp)

2) For making the castings, we have made a tilting type Vertical
Gravity Die Casting machine with Refractory Crucible (to avoid iron pick-up if cast Iron Crucible is used) with top heating lid (heating coils are placed underneath the opening and closing type lid) and Euro therm thyristor control power panel, Hydraulic valves and power pack system and PLC panel. We operate the machine with holding time of 17 sec and solidification time of 25 sec. Even though we get good castings, we face many parts with short molding.

We seek your kind advice for solving the above problems.

Answer
Dear Govindraju,
To the best of my knowledge following can meet your requirement:
1) The alloy must not have iron more then 0.3%
2) Solutionising temp 535*c and hold it for 4.5 hrs and quench
3) Titanium in alloy should be 0.12  to 0.18%
4) Degas the bath with clorine base degassing not by dry nitrigen
I am sure you will get what are you searching for.
Regards,
RP SHARMA
8800361391

Metallurgy

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RAJINDER PRASAD SHARMA

Expertise

Questions that i can answer:- 1-sand casting of cast iron,S.G. iron,steel and aluminium alloys 2-Gravity die casting of aluminium 3-Low pressure die casting of aluminium 4-High pressure die casting of aluminium 5-Failure analysis of ferrous and non-ferrous castings Questions that i can`t answer:- 1-testing of iron and steel 2-Problem related to welding 3-Problems related to corrosion 4-Amorphous metals,rubbers,nylon,plastics and plastic moulding

Experience

1-Sand casting and ferrous and non-ferrous alloys 2-Gravity die casting,low pressure die casting,high pressure die casting of aluminium alloys.With a specialisation in auto-mobile components castings. 3-Alloy steel making on arc furnace,AOD,VOD,Con-cast root of alloy steel making. I have been working as Foundry man since last 27 years.

Organizations
Hindustan motors Ltd.

Education/Credentials
I am a Metallurgical Engineer graduated from National institute of Technology,warangal(India) in 1984 and in 1991 i completed my masters degree in business administration(M.B.A.) from Institute of Management Technology,Ghaziabad(India).

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