17-4PH steel has low thermal conductivity and large billet size (cross section). It needs to be heated for a long time to reach the forging temperature. In order to shorten the residence time of forging billet in the high temperature furnace, it is generally required to preheat it for about 2h at 990-1020 ℃. Then put the preheated blank into the high temperature furnace for heating. When the temperature reaches the forging temperature (1180~1230 ℃), it should be immediately taken out of the furnace for forging after holding for about 1.5h to prevent overheating, overburning of the workpiece and similar copper rich phase precipitation of the alloy when the heating temperature is too high.

Color of stainless steel pneumatic butterfly valve
I'm afraid the stainless steel products that everyone first came into contact with were stainless steel tableware. We all know that their color is bright. Some flat stainless steel can almost be used as mirrors.
So is the color of all stainless steel products bright? Neither.
Some customers think that the color of stainless steel pneumatic butterfly valve should be relatively bright. In fact, we will find that some kinds of stainless steel pneumatic butterfly valves are snow-white or even dark silver gray. For example, 316L stainless steel bellows is not bright in snow white color.
I once thought that the bright color of 304 stainless steel pneumatic butterfly valve is the way to distinguish 304 from 201 pneumatic butterfly valve made of ordinary materials. Later, I learned that some 201 pneumatic butterfly valves are also very bright, while some 304 pneumatic butterfly valves are very dark. In fact, the bright color of stainless steel pneumatic butterfly valves is mainly due to the use of electroplating or polishing, while some 304 stainless steel pneumatic butterfly valves will reduce their luster due to the manufacturing process, such as the use of acid pickling, but the acid and alkali resistance will not be affected.