316 stainless steel belongs to austenitic stainless steel. The key to high temperature resistance is the addition of 2.0% to 3.0% Mo element. The presence of this element enables 316 stainless steel to maintain stable chemical and mechanical properties under high-temperature environments.

The temperature resistance of 316 stainless steel pipes shows significant environmental dependence:
Oxidizing environment: It is recommended that the temperature for long-term continuous use should not exceed 800°C; otherwise, the oxide film may fail due to continuous oxidation.
Non-oxidizing environment: Under anaerobic or low-oxygen conditions, it can withstand high temperatures of around 1200°C, and even 1300°C for short-term intermittent use.
Load softening temperature: About 950°C, that is, the critical temperature at which the material begins to soften under stress conditions.

The range of high temperatures that 316 stainless steel can withstand is roughly 1200-1300 degrees, and it can be used under relatively harsh conditions. The reason why 316 stainless steel can withstand such high temperatures is that the addition of Mo element to 316 stainless steel greatly increases its corrosion resistance and high temperature strength.

After quenching, but before tempering, the hardness of 45 steel is greater than HRC55 (up to HRC62) to be qualified.
The highest hardness in practical application is HRC55 (HRC58 for high-frequency quenching).

Quenching hardness:
Quenching is to change the internal structure of steel by rapid cooling, thereby increasing its hardness and strength. For 45 steel, the hardness after quenching can usually reach HRC55-58, and the limit value can even reach HRC62. However, this requires specific conditions to achieve, such as appropriate heating temperature, holding time and quenching cooling rate. It is worth noting that the hardness of 45 steel after quenching may be higher before tempering treatment, so in practical applications, the qualified standard is usually set to a hardness greater than HRC55.
Quenching and tempering hardness:
Unlike quenching, quenching and tempering treatment aims to eliminate the internal stress generated by quenching through tempering, so that the steel can maintain a certain hardness while improving its toughness and plasticity. After quenching and tempering treatment, the hardness range of 45 steel is usually between HRC20-HRC30. This hardness range enables 45 steel to have a certain load-bearing capacity and wear resistance while maintaining good processing performance.

The temperature that a prepainted sheet can withstand varies depending on the coating and substrate.
Ordinary polyester-coated prepainted sheet can withstand a temperature of 120-150 °C for a short time, and the temperature should not exceed 80 °C for a long time. Excessive temperature will cause the coating to soften, discolor, and age faster.
Silicon-modified polyester-coated prepainted sheet has good heat resistance and can withstand 150-200 °C for a short time, and the long-term use temperature is around 120 °C.
Fluorocarbon-coated prepainted sheets have certain high temperature resistance and can withstand a high temperature of about 200 °C for a short time, and the long-term use temperature is around 150 °C.
The substrate material will also affect the tolerance temperature. If the substrate is a steel plate, it has a higher melting point, but the heat resistance of the coating will limit the overall high temperature resistance.
In actual use, the frequency and speed of temperature changes must also be considered. Frequent temperature fluctuations will affect the performance of prepainted sheet.