Reasons for Solving Workpiece Quenching Cracks
During the quenching process, workpieces may experience cracking or deformation. To prevent cracking in quenched workpieces and minimize shape distortion, the basic principle is to try to reduce internal stresses during heating and cooling while ensuring that the microstructure and performance of the steel after quenching meet requirements. Pre-cooling quenching, dual-medium quenching,分级 quenching, and isothermal quenching can all achieve this principle to varying degrees. In addition, measures to prevent cracking include:
1. **Workpiece Design**: The shape of the workpiece should be as simple and symmetrical as possible, pump pipe quenching equipment, avoiding abrupt changes in cross-section size and sharp corners. Otherwise, the workpiece may not only easily distort in shape during quenching but also crack.
2. **Material Selection**: For workpieces with complex shapes that are prone to shape distortion and cracking during quenching, alloy steels with higher hardenability should be used. This allows cooling in media with lower cooling capacity or graded quenching, reducing internal stress during quenching. Shaft medium-frequency quenching equipment, wind drill head welding equipment application.
Quenching technology is widely used in modern mechanical manufacturing industries. Important parts in machinery, especially steel components used in automobiles, airplanes, and rockets, almost always undergo quenching treatment. To meet various technical requirements of different parts, various quenching technologies have been developed. For example, based on the treated area, there are whole, partial, and surface quenching; according to whether the phase transformation is complete during heating, there are complete quenching and incomplete quenching (for hypo-eutectoid steel, this method is also called subcritical quenching); according to the content of the phase transformation during cooling, there are graded quenching, isothermal quenching, and under-speed quenching, etc.
3. **Forging and Preliminary Heat Treatment**: For forgings of alloy steel workpieces with larger cross-sectional dimensions and high-alloy tool steel workpieces, repeated upsets and draw-outs are required to better eliminate dendritic segregation and carbide segregation. Proper normalizing and annealing should be conducted to eliminate network-like and angular carbides, refining the original structure of the steel before quenching. Segregation and other poor original structures will exacerbate shape distortion during quenching and increase the tendency to crack.
4. **Heating**: When loading workpieces into the furnace, avoid single-sided heating. Pay attention to placing them flat to avoid deformation due to their own weight at high temperatures. Long rods and shaft parts are best heated by suspension in a well-type furnace or salt bath furnace. For large workpieces, high-alloy steel workpieces, and unevenly thick/thin workpieces, a segmented temperature rise or preheating method should be adopted to lower the heating speed and reduce temperature differences among various parts, thereby minimizing shape distortion caused by uneven heating. Thin-walled rings and other parts that are prone to shape distortion during cooling can be loaded into appropriate fixtures for heating and cooling, reducing shape distortion. A lower heating temperature can make austenite grains finer, weakening shape distortion during quenching and reducing the tendency to crack. High-carbon steel is prone to surface cracks during cooling due to surface decarburization, so care should be taken to prevent decarburization when heating high-carbon steel workpieces for quenching. Blind holes that do not need to be hardened should be blocked with asbestos rope before the workpiece is loaded into the furnace to avoid cracking during cooling.
5. **Cooling Operation**: To reduce shape distortion, the quenched workpiece should be immersed in the cooling medium as uniformly as possible. At the same time, ensure that the resistance of the medium to the workpiece's immersion is as small as possible.
6. **Straightening**: Usually performed after the workpiece has cooled to room temperature or during tempering.
7. **Crack Inspection**: Surface cracks can generally be seen with the naked eye. To more clearly display cracks, the workpiece can be cleaned with kerosene, dried, and then coated with a layer of chalk powder, at which point the cracks will appear as moist streaks. Important parts can be inspected using various non-destructive testing methods.
8. **Application Scope of High-Frequency Shaft Quenching Equipment [Induction Heating Equipment] Produced by Our Company**:
1. Quenching of various gears, chain wheels, and shafts;
2. Quenching of various half-axes, leaf springs, shift forks, valves, rocker arms, ball studs, and other automobile parts;
3. Quenching of various internal combustion engine parts, reducer parts, and online quenching of claw hammers;
4. Quenching treatment of machine tool guides (lathes, milling machines, planers, punch presses, etc.);
5. Quenching of various pliers, knives, scissors, axes, hammers, and other hand tools;
6. Internal wall quenching of concrete pump pipes and heat treatment of the internal walls of concrete delivery pump pipelines.
For more information about high-frequency brazing equipment, please visit www.guoyunwu.com or call the hotline at 13937100064.