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2023-7-24 08:08 |
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发表于 2019-4-17 22:26:56
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Q! h) |/ v4 s3 \这里有一边文章是我的老领导总结的，你可以看看，但是是英文版本。正对A148 90-60, 105-85, 甚至更高强度钢种的热处理Heat treatment Guildlines: x" R; F9 g8 [! X% S5 i! d, Z. _
1) A normalizing heat treatment at 900 C (prior to the quench and temper heat treatment) is preferred, especially for parts that might also require low temperature impact properties. However, it is not absolutely necessary to achieving tensile properties in these grades of steel. A normalizing heat treatment will help toward homogenizing (reducing chemical segregation) the chemical composition and will put the steel through two additional grain refining cycles (one during heating up through the ferritic to austenitic phase transformation, and one during cooling through the austenitic to ferritic phase transformation). Refining grain size is one of the best ways to improve ductility and toughness in steel. Normalizing implies air cooling from the 900 C temperature, NOT slow cooling in the furnace.
W/ q+ r" F% X3 v, b2) In preparation for water quenching, heat the castings to 900 C (+/-10C) to obtain a fully austenitic microstructure. Ensure that the castings are in the furnace for an adequate length of time, depending upon casting thickness, total furnace load, and furnace fire power (BTU input), that the parts meet the 900 C temperature required (not just the furnace air temperature).+ I+ k% v1 {' I
3) Transfer the 900 C castings from the furnace to a water quench tank in 2 minutes or less to ensure rapid cooling occurs from the 900 C temperature. Water temperature must be monitored and less than 35 C at the time of quenching. Good agitation of the water is required all around the surfaces of the castings to ensure that the steam layer between the hot castings and the water is constantly disturbed and broken up to keep cold water in contact with the casting to ensure a good quench. Make certain that the parts are loaded into steel baskets that allow good circulation around all surfaces of the parts. Do NOT dump parts into the water quench tank or a “capture basket” that has rubber tires or other material that might insulate the casting surfaces and prevent rapid circulation of water around the parts and therefore prevent good quenching. Violent propeller type agitation is preferred, but good pump agitation will also work for this grade of steel, and other low carbon steels not requiring hardnesses above 300 BHN..
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发表于 2019-4-18 16:34:41
