Die casting waste heat water in large scale high manganese steel jaw plate toughening

Die casting waste heat water in large scale high manganese steel jaw plate toughening
Application of lost foam casting process to produce large jaw plate, successfully solve the 2 major problems of thermal cracking and deformation, and thus shorten the processing cycle, reduce production costs.
High manganese steel jaw plate size: 1610mm * 920mm * 210mm single 1100kg.
1 process requirements
1.1 model equipment
The product belongs to the large and small batch, using EPS panel moulded by hand.EPS plate should be in under the premise of "ensuring the strength, as far as possible to reduce density" principle, choose the density of 0.015kg / L, 2000mm x 1000mm * 200mm of EPS board molding, quality model for casting 1 / 450 to 1 / 500.
1.2 gating system
Vertical casting, teeth before dumping 15 degrees, back 1 / 3 along the reinforcing rib arranged inside the gate around, sectional area of 40mm x 20mm, straight gate & Oslash 50nqln. riser 2, l8mm x 250mm. Both the box combination, rigid connection technology.
1.3 coatings and coatings
Magnesium olivine powder aggregate, the effect is good, the price is also cheap.
It is worth noting that the jaw plate is a plate, in the paint drying process is very prone to distortion, so, to take appropriate measures to prevent deformation, coating thickness of 1.5 ~ 2.0mm.
1.4 material ZGMn18Cr2
Chemical composition of W is: 1.10% ~ 1.25%C; 16% ~ 19%Mn; 2% ~ 2.5%Cr; 0.3% ~ 0.5%Mo.
The diversification of the alloy improves the mechanical properties and the service life of the casting, and the replacement time of the jaw plate is prolonged.
1.5 sandbox and buried box
Large high manganese steel jaw plate shape is relatively simple, but a large surface area, buried box slightly mistake occur deformation, buried in sand process to achieve uniform sand filling and microseisms. Try to shorten the hit box and into the water between the time difference, less heat loss of the casting and take measures:
(1) the model is placed in the basket, at the same time buried type;
(2) the design of the side with the negative pressure sand box.
Large castings in the casting process easily destroy runner coating, the sand into the mold cavity, white defects, reduced wear parts of life, to strictly in accordance with the requirements of the process, do the runner hard wired.
1.6 pouring
High manganese steel liquidity better, pouring temperature can lead to coarse grain. The mechanical properties decreased significantly. Therefore, the control of high manganese steel casting temperature, to obtain high performance of the casting is very important. Using EPC process, due to the bubble in the gasification process to absorb heat, so tapping liquid steel and pouring temperature to compared with the traditional process, the high 20 to 30 DEG C. Concrete is 1460 DEG C released, quickly skimming, pouring of 1420 DEG C, a vacuum degree control in 0.04 ~ 0.03mpa, after confirmation of the liquid steel solidification constant pressure, removal of sprue cup, the sand box moved to the falling sand hopper, do to fight a box of sand casting into the water ready to.
The theory on the basis of the 1.7 high manganese steel using water toughening treatment
High manganese steel water toughening to solution of the carbides in austenite, obtain single-phase austenite.
High manganese steel as cast microstructure of austenite and carbide, casting cooling process, the temperature dropped to 950 DEG C, carbides begin to expand outward from the austenite and 350 DEG C to stop. During heating carbide in the direction opposite to that of the free.
Characteristics of EPC process is casting a combination of pouring temperature synchronization; dry sand buried type, sand removal easily, casting full time control of water temperature. Therefore, conditions for utilization of waste heat in carbide on the verge of austenite before quenching water solution.
If you can control the pouring temperature (control crystal structure is not coarse) and water temperature (carbide has not been separated from the austenite), the use of waste heat water treatment effect is significantly better than the two warming of the traditional water treatment process.
Detection methods are as follows:
(1) compared with the EPC process, the use of residual heat water treatment to obtain austenite in vitro basic no free carbide, for single phase austenite, two heating water toughening treatment can see a little carbide.
(2) rapid detection using magnets: EPC use of waste heat water treatment to obtain the casting, feel less magnetic, and the traditional two heat treatment of water treatment of the casting there are some of the feeling of magnetic absorption.
1.8 box and water treatment
Water toughening treatment is the key to control water temperature and speed of water entry. In small-scale production of high manganese steel, methods of operation: foundry crane box cast down in the shakeout bucket basket, after removing the sand box, a crane to lift the basket, at this time, sand all fall into sand drop bucket, and separation of sand and casting crane provided hanging blue into the water. The operation is orderly, the effect is very good. But in the large, such a method of operation is not casting serious deformation is hot cracking. The formation
The reasons are as follows:
(1) the deformation is caused by the water inlet angle and direction. The traditional two heating water treatment is also often deformed.
(2) the heat is split into the water speed is slow, poor thermal conductivity of high manganese steel, cause tissue supercooling uneven changes, the internal should be more stress, casting cracking. In large scale high manganese steel parts by using waste heat water toughening treatment must solve the water entry angle
And into the water speed. Therefore, only the front of the Blue Crane (control angle into the water) and side vent type negative pressure sand box (for sand and lifting).
Link for fast into the water, we design fast decoupling the past hook slowly falling into the water, into the Blue Crane carrying large jaw plate, vertical direction, with the speed of free fall rapidly into the water, and achieved good results.
2 conclusions
Application of expendable pattern casting process, using waste heat of water toughening treatment production of large jaw plate has in Shulan City, Jilin Province, Saddle Ridge iron ore stone field, Heilongjiang peony Jiang Zhiyu quarry, Liaoyuan gold, the user reflect good, agreed that performance is superior to the traditional craft production products.
(1) application of EPC process to produce large scale high manganese steel, and use waste heat of water toughening treatment process is feasible, the key lies in the strict quality management and necessary tooling.
(2) using this technology can shorten the supply cycle, improve production efficiency, achieve zero inventory, significantly reduce production costs, improve market competitiveness.