Gasifier Model

Furnace should be determined in accordance with the requirements of different types of processes and artifacts

1. Can not be finalized for production batch, the workpiece size does not equal more types, requiring versatile craft,
Versatility, the choice of a box furnace.

2. When heated long axis and a long screw, tubes and other parts, it can be used in deep furnace.

3. Small quantities of carburizing parts, the choice of pit gas carburizing furnace.

4. For high-volume cars, tractors and other parts of the production gear carburizing optional continuous production line or box-type multi-purpose furnace.

5. When heated to a blank sheet stamping mass production, the best selection of rolling furnace, roller hearth furnace.

6. Part of the batch of stereotypes, the choice of pusher or belt type resistance furnace (pusher furnace or cast belt furnace) production

7. Small mechanical parts such as: screws, nuts and other optional vibrating mesh belt furnace or hearth furnace.

8. Ball and Roller heat treatment can be used within the spiral rotary tube furnace.

9. Non-ferrous metal billet pusher furnace can be used in high-volume production, while the non-ferrous metal small parts and materials can be air circulation oven.

Defects and heating control

First, overheating

We know that overheating of the heating during the heat treatment most likely to result in coarse austenite grains, the mechanical properties of the parts is reduced.

1. General overheating: heating temperature is too high or too long holding time at high temperatures, causing austenite grain coarsening called overheating. Coarse austenite grain size will result in reduced strength and toughness of steel, brittle transition temperature, deformation cracking tendency increases during quenching. The cause of overheating is out of control or mixing furnace temperature meter (often do not understand the process occurred). Overheating tissue may be annealed, normalizing or tempering times, under normal circumstances, re-austenitizing grain refinement.

2. Genetic fracture: are steel tissue overheating, re-Hardening, although make austenite grain refinement, but sometimes still appear coarse granular fracture. Generate more controversial theory of genetic fracture, but had the heating temperature is generally considered too high and the like leaving debris MnS dissolved in austenite and enriched in the crystal interface, and when cool these inclusions will precipitate along the grain interfaces, Yi along the coarse austenite grain boundary fracture upon impact.

Genetic 3. coarse organizations: Coarse martensite, bainite, when steel Wilcoxon tissue re austenitizing to slow heating to a conventional quenching temperature, even much lower, its austenite grain coarse grains is still a phenomenon known as hereditary organization. To eliminate hereditary thick tissue, it can be used repeatedly intermediate annealing or tempering process.

Second, over the burning phenomenon

Heating temperature is too high, not only causing austenite grain coarsening, and the emergence of local grain boundary oxidation or melting, causing grain boundary weakening, called over-burning. After burning properties of steel over the serious deterioration, cracks formed during quenching. Burnt tissue can not be restored, only to be scrapped. Therefore, work to prevent the occurrence of over-burning.

Third, decarbonization and oxidation

When steel is heated, the surface of the carbon with the medium (or atmosphere) oxygen, hydrogen, carbon dioxide and water vapor react, reducing the surface carbon concentration after decarburization known, from carbon steel quench surface hardness, fatigue strength and resistance reduced wear and surface residual tensile stress is easy to form a mesh surface cracks.

When heated, the surface layer of the steel and iron and alloy elements and the media (or atmosphere) oxygen, carbon dioxide, water vapor and other phenomena occur in the reaction of the oxide film is called oxidation. High temperatures (generally above 570 degrees) oxidation of the workpiece dimensional accuracy and surface brightness deterioration of the oxide film poor hardenability steel parts prone to hardening soft spots.

In order to reduce oxidation and decarbonization of prevention measures include: surface coatings, with a stainless steel foil package sealing heating, salt bath furnace heating, heating using a protective atmosphere (inert gas such as purified, control the furnace carbon potential), flame burner (the furnace gas was reducing)

Fourth, hydrogen embrittlement

Ductility and toughness lower phenomenon when heated hydrogen-rich atmosphere called hydrogen embrittlement of high strength steel. Workpiece appear by the addition of hydrogen embrittlement treatment (such as tempering, aging, etc.) can also eliminate hydrogen embrittlement, the use of vacuum, low hydrogen atmosphere or an inert atmosphere heated to avoid hydrogen embrittlement.