Heat resistance refers to the ability of die steel metal materials to resist medium corrosion and mechanical load at the same time at high temperature. Wood is easy to be damaged when working at high temperature. It includes thermal stability and thermal strength.

1)热稳定性

1) Thermal stability

热稳定性是指金属材料在高温下抵抗氧化和燃气腐蚀的能力。金属在高温下常见的腐蚀破坏是气体腐蚀，其中以氧化常见，故热稳定性通常是指金属抵抗氧化的能力。热稳定性高的材料，在高温下使用时就不易产生剧烈的氧化而导致损坏。

Thermal stability refers to the ability of metal materials to resist oxidation and gas corrosion at high temperature. The common corrosion damage of metal at high temperature is gas corrosion, among which oxidation is the most common, so thermal stability usually refers to the ability of metal to resist oxidation. Materials with high thermal stability are not easy to be damaged due to severe oxidation when used at high temperature.

2)热强性

2) Thermal strength

热强性是指金属材料在高温下抵抗塑性变形和破坏的能力，亦称金属高温强度或称热强度。试验表明，随着温度升高，金属材料一般是强度降低而塑性增加(见图61)。例如30CrMnSlA钢，常温强度ob＝1100MPa，在550度时，ob只有550MPa。另外，在高温下，随着加载时间的延长，金属的强度还要进一步下降。

Thermal strength refers to the ability of metal materials to resist plastic deformation and failure at high temperature, also known as metal high temperature strength or thermal strength. The test shows that with the increase of temperature, the strength of metal materials generally decreases and the plasticity increases (see Figure 61). For example, 30crmnsla steel, the room temperature strength ob = 1100mpa, at 550 degrees, ob is only 550MPa. In addition, at high temperature, with the extension of loading time, the strength of the metal will further decline.

因此，金属材料在高温下的力学性能，除了考虑载荷因素外，还要考虑温度和时间因素的影响，从而建立高温强度指标。常用的高温强度指标有高温瞬时强度、蠕变强度和持久强度等。

Therefore, the mechanical properties of metal materials at high temperature should not only consider the load factor, but also consider the influence of temperature and time factors, so as to establish the high temperature strength index. The commonly used high temperature strength indexes include instantaneous strength, creep strength and rupture strength.