Analysis of heat treatment technology of Hi-Mn casting liners (1)
( Yue Weiguo, Yuan Fang, Liu Jincang)
Citic Heavy Industry Luoyang Heavy Iron Industry Co. Ltd.
Abstract: The lining plate is an essential part of the composition of the machinery and equipment on the mine. In the production of the ore, it needs to be in direct contact with the ore material. After being subjected to a lot of pressure and wear, it can also maintain its original quality and performance during its service life; this is both a liner advantage and a liner selection requirement. High Manganese casting liners can meet this requirement; its production demand is generally huge. In the condition of casting, the liner can not meet the requirements of bearing capacity and wear resistance, and its toughness and impact resistance need to be improved in the heat treatment process. Based on this, relevant personnel needs to study the process involved in this link, find the appropriate heat treatment parameters, and formulate a reasonable heat treatment program.
Key Words: High manganese steel liner; Heat treatment process; application
In the production of ore, there are many types of lining plates used in related equipment, large, medium and small size can be used in the ball mill, and different types of lining plates have different requirements for the heat treatment process and parameter standards, relevant personnel should also consider these differences, prepare different heat treatment implementation program, and through comparison, distinguish different high manganese steel lining plate treatment, treatment process. In this paper, the heat treatment process of high manganese steel liner is analyzed.
1.Quenching process differences of large, medium and small casting liners
In the heat treatment of liner, the parameters such as temperature and time must be involved, and the values of these parameters are different in different states, the relationship between the size of lining plate and the way of furnace installation was found
1)The large size of the casting liners
This kind of scale lining board has a complex composition and large size, which brings trouble to heat treatment, and its heat treatment link needs to solve two problems, one of which is the problem of thermal stress, which should be less than the tissue stress, but in practice, it is just the opposite. Therefore, the related personnel needs to reduce the thermal stress, generally, through adjusting the temperature to achieve the goal, the temperature parameters need to go through the process of average temperature, rising temperature, average temperature, rising temperature, the first average temperature should be kept below 400 °C, after the average temperature should be about 680 °C, it is also necessary to control the rate of warming during temperature changes.
The second carbides dissolve and crack, the crack problem, these problems are caused by high temperature, the heat treatment temperature is too high, the duration is too long, will cause the manganese element in the lining board to separate from the product, after entering the quenching stage, relevant, products will not form a single pure austenite structure, and prone to cracks.
Personnel required/high-temperature insulation Coefficient and insulation time should be adjusted to meet the requirements. The maximum holding time was 1.8 min/mm, the corresponding holding time was 3 H, and the minimum holding time was 1.5 min/mm. The corresponding holding time is 2.5 h.
2) Medium size of the casting liners
The thickness of the medium-sized liners is also relatively large. In Heat treatment, if a single set of AUSTENITE is to be obtained. Weaving, crack control, and the need to control the high-temperature insulation time and before quenching, make it in the insulation state. The average temperature coefficient is 1.5 min/mm. After heating up, the relative people need to adjust the average temperature coefficient. In the warming-up state, it should ensure the heating uniform, reach the quenching temperature, degrees, and make it in the insulation state, high-temperature Insulation Coefficient 0.8 min/mm.
3) The small size of the casting liners
This kind of lining plate is small in scale and size, and its temperature should be controlled below 745 °c, the temperature will rise to the quenching temperature quickly, and the heat preservation coefficient is mainly 1.45 MIN/MM.
The liner’s performance can be improved by heating and quenching the liner in the state of heat preservation. In the quenching process of the large, medium, and small type steel linings, the temperature and heating rate are the critical control objects.