一. Why does the heat treatment tray need to be resistant to high temperatures?
The heat treatment tray is the core device for carrying the workpiece for heating, heat preservation, cooling and other processes. Its high temperature resistance is determined by the essential needs and functional positioning of the heat treatment process. The specific reasons are as follows:
1. High temperature environment requirements of the heat treatment process
The core processes of heat treatment (such as quenching, annealing, normalizing, tempering, etc.) must be carried out in a high temperature environment, for example:
The quenching temperature of steel materials is usually 800~1200℃ (such as the quenching temperature of medium carbon steel is about 840℃, and the quenching temperature of high-speed steel can reach 1220℃);
The solution treatment temperature of aluminum alloy is about 500~600℃;
The process temperatures of vacuum heat treatment, carburizing, etc. are also generally in the range of 500~1000℃.
The tray needs to be in direct contact with the high-temperature furnace or medium. If the material is not resistant to high temperature, it will quickly oxidize, soften, deform or even melt, causing the workpiece to fall, process failure or equipment damage.
2. Stability requirements for bearing workpieces
The weight of the workpiece at high temperature will exert a continuous load on the tray. If the strength of the tray material decreases significantly with the increase of temperature (such as the sudden drop in strength of ordinary steel above 400℃), structural collapse may occur, causing the workpiece to be scrapped or a safety accident.
For example, in a continuous heat treatment furnace, the tray needs to move back and forth with the conveyor belt for a long time. The creep resistance at high temperature (the ability of the material to slowly deform under a constant load) is the key to ensuring stability.
3. Anti-oxidation and corrosion resistance requirements
In a high temperature environment, oxygen in the air, protective gas in the furnace (such as CO, CO₂ in the carburizing atmosphere) or quenching medium (such as salt bath, oil) will react chemically with the tray material, resulting in the peeling of oxide scale and the formation of corrosion pits.
The peeling oxide scale may contaminate the surface of the workpiece or block the pipes in the furnace, and corrosion will weaken the strength of the tray. High temperature resistant materials (such as stainless steel and nickel-based alloys) usually have better antioxidant film stability and corrosion resistance.
4. Economic demand for reuse
Heat treatment is a batch process, and the tray needs to be repeatedly put in and out of the high-temperature furnace (may be cycled dozens of times a day). If the material is not resistant to high temperatures, frequent replacement of trays will increase production costs (such as downtime and consumables costs).
For example, a tray made of ordinary carbon steel may be scrapped after hundreds of high-temperature cycles, while a high-temperature resistant alloy tray can be used tens of thousands of times, with a lower overall cost.
二. What is the maximum temperature that a heat treatment tray can withstand?
The maximum temperature that the tray can withstand depends on the material type and specific composition. The temperature range of common materials is as follows:
Extreme cases in special scenarios
Aerospace-grade high-temperature alloy trays: using single-crystal nickel-based alloys (such as Rene N5 developed by NASA), which can be used for short-term service at temperatures above 1400°C and are used for ultra-high temperature heat treatment of aircraft engine components, but the cost is extremely high.
Composite material trays: such as metal skeleton + ceramic coating (such as ZrO₂ coating), can withstand temperatures above 1500°C through gradient design and are used in extreme working conditions (such as nuclear material processing).
三. Other factors affecting the high-temperature resistance of trays
Heating rate and insulation time:
Rapid heating (such as heating more than 50°C per minute) will increase the thermal stress of the material and may cause cracking; long-term insulation (such as continuous use for more than 10 hours) will accelerate material creep.
Atmosphere:
Reducing atmosphere (such as H₂), carburizing atmosphere (such as CO) or sulfur-containing atmosphere will reduce the actual temperature resistance of the tray. For example, Inconel 601 can withstand 1250℃ in pure oxygen, but may drop to below 1100℃ in a sulfur-containing atmosphere.
Surface state:
If there is oil and scale accumulation on the surface of the tray, local hot spots will form, accelerating the degradation of the material. Regular surface cleaning can extend the service life.
4. How to choose a high-temperature resistant tray?
Match the material according to the process temperature:
If the process temperature is ≤1000℃, 310S stainless steel can be selected;
If the temperature is 1000~1300℃, nickel-based alloys (such as Inconel 601) or iron-chromium-aluminum alloys are preferred;
Ultra-high temperature scenarios (>1300℃) require ceramics, graphite or composite materials.
Consider the number of cycles and loads:
High-load and high-cycle frequency scenarios (such as continuous production lines) require materials with high creep strength (such as Inconel 718).
Focus on cost performance and maintenance cost:
Ceramic trays have high initial costs, but have long life and do not require frequent maintenance; metal trays have lower costs, but require regular inspections for oxidation and deformation.
From the above analysis, it can be seen that high temperature resistance is the core performance of heat treatment trays, and its limit temperature is determined by the scientific design of the material. In practical applications, it is necessary to comprehensively select the process conditions, economy and reliability.
一. Why does the heat treatment tray need to be resistant to high temperatures?
The heat treatment tray is the core device for carrying the workpiece for heating, heat preservation, cooling and other processes. Its high temperature resistance is determined by the essential needs and functional positioning of the heat treatment process. The specific reasons are as follows:
1. High temperature environment requirements of the heat treatment process
The core processes of heat treatment (such as quenching, annealing, normalizing, tempering, etc.) must be carried out in a high temperature environment, for example:
The quenching temperature of steel materials is usually 800~1200℃ (such as the quenching temperature of medium carbon steel is about 840℃, and the quenching temperature of high-speed steel can reach 1220℃);
The solution treatment temperature of aluminum alloy is about 500~600℃;
The process temperatures of vacuum heat treatment, carburizing, etc. are also generally in the range of 500~1000℃.
The tray needs to be in direct contact with the high-temperature furnace or medium. If the material is not resistant to high temperature, it will quickly oxidize, soften, deform or even melt, causing the workpiece to fall, process failure or equipment damage.
2. Stability requirements for bearing workpieces
The weight of the workpiece at high temperature will exert a continuous load on the tray. If the strength of the tray material decreases significantly with the increase of temperature (such as the sudden drop in strength of ordinary steel above 400℃), structural collapse may occur, causing the workpiece to be scrapped or a safety accident.
For example, in a continuous heat treatment furnace, the tray needs to move back and forth with the conveyor belt for a long time. The creep resistance at high temperature (the ability of the material to slowly deform under a constant load) is the key to ensuring stability.
3. Anti-oxidation and corrosion resistance requirements
In a high temperature environment, oxygen in the air, protective gas in the furnace (such as CO, CO₂ in the carburizing atmosphere) or quenching medium (such as salt bath, oil) will react chemically with the tray material, resulting in the peeling of oxide scale and the formation of corrosion pits.
The peeling oxide scale may contaminate the surface of the workpiece or block the pipes in the furnace, and corrosion will weaken the strength of the tray. High temperature resistant materials (such as stainless steel and nickel-based alloys) usually have better antioxidant film stability and corrosion resistance.
4. Economic demand for reuse
Heat treatment is a batch process, and the tray needs to be repeatedly put in and out of the high-temperature furnace (may be cycled dozens of times a day). If the material is not resistant to high temperatures, frequent replacement of trays will increase production costs (such as downtime and consumables costs).
For example, a tray made of ordinary carbon steel may be scrapped after hundreds of high-temperature cycles, while a high-temperature resistant alloy tray can be used tens of thousands of times, with a lower overall cost.
二. What is the maximum temperature that a heat treatment tray can withstand?
The maximum temperature that the tray can withstand depends on the material type and specific composition. The temperature range of common materials is as follows:
Extreme cases in special scenarios
Aerospace-grade high-temperature alloy trays: using single-crystal nickel-based alloys (such as Rene N5 developed by NASA), which can be used for short-term service at temperatures above 1400°C and are used for ultra-high temperature heat treatment of aircraft engine components, but the cost is extremely high.
Composite material trays: such as metal skeleton + ceramic coating (such as ZrO₂ coating), can withstand temperatures above 1500°C through gradient design and are used in extreme working conditions (such as nuclear material processing).
三. Other factors affecting the high-temperature resistance of trays
Heating rate and insulation time:
Rapid heating (such as heating more than 50°C per minute) will increase the thermal stress of the material and may cause cracking; long-term insulation (such as continuous use for more than 10 hours) will accelerate material creep.
Atmosphere:
Reducing atmosphere (such as H₂), carburizing atmosphere (such as CO) or sulfur-containing atmosphere will reduce the actual temperature resistance of the tray. For example, Inconel 601 can withstand 1250℃ in pure oxygen, but may drop to below 1100℃ in a sulfur-containing atmosphere.
Surface state:
If there is oil and scale accumulation on the surface of the tray, local hot spots will form, accelerating the degradation of the material. Regular surface cleaning can extend the service life.
4. How to choose a high-temperature resistant tray?
Match the material according to the process temperature:
If the process temperature is ≤1000℃, 310S stainless steel can be selected;
If the temperature is 1000~1300℃, nickel-based alloys (such as Inconel 601) or iron-chromium-aluminum alloys are preferred;
Ultra-high temperature scenarios (>1300℃) require ceramics, graphite or composite materials.
Consider the number of cycles and loads:
High-load and high-cycle frequency scenarios (such as continuous production lines) require materials with high creep strength (such as Inconel 718).
Focus on cost performance and maintenance cost:
Ceramic trays have high initial costs, but have long life and do not require frequent maintenance; metal trays have lower costs, but require regular inspections for oxidation and deformation.
From the above analysis, it can be seen that high temperature resistance is the core performance of heat treatment trays, and its limit temperature is determined by the scientific design of the material. In practical applications, it is necessary to comprehensively select the process conditions, economy and reliability.
