固溶退火 亦即碳化物固溶退火, 一种将成品件加热至1850 deg F(摄氏1010度)以上而脱除碳化物沉淀(即从不锈钢固体溶液中逃逸的碳)的工艺, 此后将其迅速降温,通常是用水淬火, 所含碳化物返回不锈钢固体溶液中.

固溶退火处理可应用于一系列的合金钢与不锈钢成分中. 对于300系列不锈钢铸件的固溶处理能产生一种没有碳化物杂质的均一的显微结构. 对于沉淀硬化合金铸件及锻件的固溶退火能产生较软的显微结构,更适于精密公差的机加工.这些合金在以最小畸变的精密公差机加工之后,有着时效硬化的潜在倾向.这些材料及工艺对有中等强度要求的车削或螺旋机件上有着普遍的应用. 这种热处理可以依照部件所需的尺寸,几何形状与表面条件,成批的在大气炉,非常压炉或真空炉中进行.小型部件也可以在连续氢气带式炉中热加工.

固溶退火与时效硬化也可用于铝合金的冲压件和铸件. 通常是在非常压批式炉进行热处理,在固溶退火之后用水对部件淬火.时效硬化则在大气中用电炉或燃气炉成批操作.

SOLUTION ANNEALED (same as CARBIDE SOLUTION ANNEALED) : A process of heating and removing carbide precipitants (carbon that has broken loose from its stainless steel solution) by heating a finished fitting to over 1,850 degrees F. and cooling it quickly, usually in water, so carbon content goes back into the stainless solution.

Solution annealing treatments are applied to a series of alloy steel and stainless steel compositions. Solution annealing of 300 series stainless steel castings produces a uniform microstructure free of carbides in the microstructure. Solution annealing of precipitation hardening cast and wrought alloys produces a soft microstructure suitable for machining to close tolerances. These alloys have the potential for Age Hardening after machining with minimal distortion of close dimensional tolerances. These materials and processes are generally applied to medium strength requirements on turned or screw machine parts. The heat treatments may be performed in batch atmosphere furnaces, non-atmosphere furnaces, and vacuum furnaces, depending on the part size, geometry, and surface condition required. Small parts may also be treated in continuous hydrogen belt furnaces.

Solution annealing and age hardening may also be applied to aluminum alloy stampings and castings. These treatments are usually performed in non-atmosphere batch furnaces with water quenching of the parts after solution annealing, and age hardening in electric or gas fired batch furnaces in air.