Process study of thin-walled Haynes 230 alloy shaped ring pieces
This paper introduces a forging process design method for thin-walled Haynes 230 alloy shaped rings, through numerical simulation, to select the appropriate process program. Verified by the actual production, according to the preferred process method to produce products in order to ensure that the ring size and performance indicators in line with the user’s order standards under the premise of reducing material consumption, and can effectively reduce the degree of deformation of the parts after finishing.
Table of Contents
Haynes 230 is the United States in the 20th century developed a Ni-Cr-W high-temperature alloy materials, the material has good high-temperature performance, under high-temperature conditions, has good corrosion resistance and durability, in actual production practice, the material deformation resistance, the forging temperature is very sensitive to the inappropriate forging temperature is very easy to cause forging organization or performance is unqualified or cracking and other defects. Currently in the domestic supply is relatively small.
Haynes 230 alloy used in combustion engines and combustion chamber position, the position of the parts shape structure for the horn modeling, the size of the end of the size difference is large, the wall thickness is thin, forging billet volume differences in various places. The ring rolling process design requirements are high. In order to improve the competitiveness of products in the international market, we must ensure that forgings to meet the conditions of the user base under the premise of reducing raw material input.
2. Forging condition
Users require the delivery of the state shown in Figure 1, this part is a thin-walled parts, and parts of the big end with the installation of the edge, the weight difference between the two ends of the unit height of the parts to reach 3 times the degree of complexity is very high. In view of the Haynes 230 alloy material forging process flow performance is poor, the design process is appropriate in the small end of the forging part to increase the price allowance, the design of the forging part shown in Figure 2.
Figure.1 Delivery state diagram
Figure.2 Forging state diagram
3. Analysis of process difficulties
The forging is designed to be symmetrically distributed in the height direction, but the difference between the unit height volume against the two end face positions and the unit height volume at the waist position is large, up to 1.5 times, the ring billet is rolled in the rolling process, the waist part of the material needs to flow to both ends to replenish the two end cavities, the high temperature alloy has poor fluidity, it is necessary to design suitable billets to reduce the final rolling process of the amount of material flow in the inner and outer diameters of the forging dimensions to reach the target size of the At the same time, the billet completely fill the mold cavity.
Users have higher technical requirements for forgings, requiring the grain size of more than 4. Haynes 230 alloy is a coarse crystalline material, the solution treatment temperature is as high as 1187-1224 ° C. In order to ensure that the grain size of forgings after heat treatment to meet the user’s standard requirements, the grain size of the forging state must be 6 to 8 levels.
4. Technology program design
In order to ensure that the forging in the mold cavity is completely filled, ring blank design must ensure that the volume of material at both ends of the billet to meet the requirements of the forging cavity volume at both ends of the rolled pieces, at the same time, forging high height, thin wall thickness, the forging process temperature decreases very quickly, we must use the appropriate method of heat preservation to ensure that the billet forging process does not appear cracking, folding and other forging defects.
Combined with the forging characteristics of Haynes 230 alloy materials, the alloy in the free forging process, it is easy to appear cracking, so the need to increase the heating temperature of the free forging process, and at the same time in order to ensure that the organization of the forging performance requirements, in the final rolling process to reduce the heating temperature, through the lower temperature to impose a certain amount of deformation to obtain the target organizational properties.
4.1 Open billet process
This stage of the heating temperature set at 1180 °C, this temperature is close to the Haynes 230 alloy solid solution temperature, this temperature under the billet plasticity is better, in the absence of cracking and other defects under the premise of obtaining a greater degree of deformation, and the use of aluminosilicate fibers covering the billet surface of billet heat preservation, can be obtained for a long period of forging operation time.
4.2 Pre-rolling and splitting stage
For the forging billet volume of each part to meet the forging molding requirements, the need for the billet waist material to the billet ends of the direction of the transfer, the formation of the two ends of the volume of large, small waist volume volume distribution. High-temperature alloy material fluidity performance is generally low, in order to ensure that the material will be transferred to the billet waist of the material to the ends of the billet, therefore, the design of the pre-roll mold cavity as shown in Figure 3.
Fig.3 Die for pre-rolling
The main silver and core spokes at the same time extrusion billet waist, the material to the billet ends of the transfer, to ensure that the billet ends of the material volume to meet the needs of forging molding, while pre-rolled billet OD surface most of the main spokes with the final rolled to fit, which can improve the stability of the billet final rolled process, to ensure that the final rolled process to obtain a larger degree of deformation in a single fire times.
4.3 Final rolling stage
In order to ensure that the organizational properties of the forging after molding, this stage is set at this stage of the billet heating temperature of 1150 °C, rolling deformation is guaranteed to be more than 30%.
According to the above program to develop process routes, the use of Deform simulation software to simulate the process of forging molding. Pre-rolling billet inner diameter completely fit the mold surface, the outer diameter of the basic fit, by measuring the volume of each part of the billet, basically meet the expectations of the material volume distribution, the final rolling billet completely fill the mold cavity, simulated molding state as shown in Figure 4.
Figure.4 Rolling process simulation results
5. Forging test manufacture
Forging weight 350kg, through numerical simulation, the rolling process requires radial rolling force of 260t, combined with the actual capacity of the company’s equipment, so the trial manufacture of 63MN hydraulic press and DK53K-700/6004500/1000 ring mill production line in our company, the equipment parameters are shown in Table 1 and Table 2.
The state of the forging after rolling is shown in Fig. 5, and the size of the forging meets the requirements of the drawing of the forging.
Table.1 63MN hydraulic press equipment parameters
|Maximum forging height/mm||Maximum forging pressure/kN||Forging accuracy/mm|
Table.2 Parameters of DK53K-700/600^500/1000 ring mill equipment
|Maximum rolling diameter/mm||Maximum rolling height/mm||Maximum rolling weight/kg||Radial rolling force/t||Axial rolling force/t||Rolling accuracy/mm|
Heat treatment parameters of forgings are shown in Table 3.
Table.3 Heat treatment parameters of forgings
|Heat treatment method||Heating temperature||Cooling method|
Figure.5 Forging molding condition
Forging organization and performance testing sampling location as shown in Figure 6, high times the organization as shown in Figure 7.
Fig.6 Sampling location schematic diagram
Fig.7 High magnification photo
Through the first batch of forgings production practice, the use of the established technology program to fully meet the production requirements of Haynes 230 forged ring, forgings size, organization and performance indicators to fully meet the requirements of user standards.
Haynes 230 alloy forgings, high-temperature billet, low-temperature rolling molding technology program for production, this program can ensure that the billet stage to obtain a wider forging temperature window, effectively reduce the billet stage billet growth of forging defects in the chances of effective reduction of the number of forging fire and processing costs.
The forging process must use aluminum silicate fibers to insulate the forging blanks to prevent cracking caused by localized temperature reduction of the blanks.
The grain size of Haynes 230 alloy forgings reaches 6~8 grade in forging state, and the grain grows to 4~5 grade after heat treatment, and the heat treatment time should be strictly controlled.
Author: He Tao, Yang Jiadian, Sun Chuanhua, Wang Panzhi