preheating time

Variation of temperature of liquid brass as well as preheating temperature and thickness of steel strip did not change the thickness variation pattern of cladding layer, but affected the holding time at individual stages and thickness of the cladding layer.

铜液温度以及钢带预热温度和厚度变化不改变复合层厚度的变化规律，但对各阶段的持续时间和复合层的厚度有影响；

The actual retrofit results show that the coefficient of heat recovery is increased greatly, and the crude preheating temperature is raised from 288 ℃ to the highest of 303 ℃, The in-vestment payback time is only half year.

实践结果表明，原油预热终温由原来已经较高的288℃进一步提高最高可达303℃，投资回收年限为半年。

The effect of preheating treatment process of cold rolls on induction heat quenched structures and the effect of heating temperature and time on structure and hardness have been studied.

研究了轧辊的预备热处理工艺对感应加热淬火组织的影响，感应加热温度和时间对组织和硬度的影响。

An air cooling curve after large workpiece preheating is calculated out. According to these curves, a suitable welding temperature and time interval are determined for repair the heavy hopper.

还介绍了采用计算方法绘出大型工件预热在常温的冷却曲线，根据该曲线即可选定焊接时合适的温度和时间范围。