ThermTech has run very large loads of stress relieving of castings on our car-bottom furnace that is 15' long x 7' wide x and 4' high.
The sub-critical annealing process typically produces a microstructure where existing pearlite dissolves into the ferritic matrix which lowers hardness and strength while improving machinability.
Gray iron and ductile iron castings are typically normalized to move the carbon from being locked in carbides or graphite into more of a pearlitic microstructure.
The full annealing process involves taking a casting to a temperature above the critical eutectoid temperature in the 1475F-1650F range for a length of time commiserate with the cross section size and then slow cooled to promote a ferritic microstructure.
Solution Annealing stainless steel castings is a process which takes the carbides that have precipitated in the grain boundaries and dissolves then into the surrounding matrix.
Many steel foundries cast low carbon or low alloy steels that require a severe water quench to adequately achieve the proper martensitic microstructure and hardness requirements.
Polymer quench hardening of steel castings like 4130, 15B41, 1045, and 5130 is the proper way to balance the necessity for rapid quench rates while minimizing the risk of quench cracking the castings.
Steel castings made from alloys in excess of 0.40% carbon content can typically be oil quench hardened to achieve their desired mechanical or hardness requirements.
In addition to austempering ductile iron we are also capable of austempering gray irons and several alloys of steel castings.
To insure that the steel castings are capable of achieving full surface hardness during subsequent hardening processing the castings may require a carbon restoration of their surfaces and we have several furnaces capable of doing this.
Most importantly to our customers we are able to run impellars and pump units where minimal oxidation occurs on internal surfaces making clean-up faster and cheaper for them.
Currently ThermTech blasts several thousand pounds of castings a day through our 96" diameter table blaster and our 36 cubic-foot tumbleblast unit.
Most austempered ductile iron castings have mechanical requirements due from either industry standards such as ASTM-897 or customer specifications.