ASTM A128 High Manganese Steel Investment Castings

ASTM A128 Grade A (UNS J91109) is Manganese steel for abrasive casting applications.
ASTM A128 / A128M – 93(2017) Standard Specification for Steel Castings, Austenitic Manganese
ASTM A128 Grade A Casting Chemical Composition:
Carbon: 1.05-1.35
Manganese: 11.0 min
Silicon: 1.00 max
Phosphorus: 0.070 max

ASTM A128A Casting

Investment casting ASTM A128 is similar to investment casting other steels, but the heat treatment is far more exacting and difficult. Sinotech begins with your 3-D CAD drawings and uses advanced modeling software to create precision mold designs. The modeling assures uniform heat flow and cooling through strategic placement of gates and gas vents.

Grades. Here are the available grades of ASTM A128A/A128M – 19

Heat Treatment. Here is a typical heat treat process we use for ASTM A128A investment castings.

First, parts are strung along a steel wire to maintain proper separation for adequate air flow, ensuring uniform heating and cooling. Strings of parts are coiled into a nest to further promote uniform air flow. The parts remain in strings through the heat treating and quenching processes.

A temperature of 1950-1975F is held for a dwell time of 2 hours. The parts are stacked on a grated style bunk in such a manner as to allow uniform heating and quenching of the parts throughout the load.  The water quench media produces adequate agitation to avoid stream pockets developing around the parts.  Quenching water does not exceed 80F.  The target time from opening of the furnace door until the load is submerged in the quench tank is 30 to 45 seconds.  Any dark spots that develop in the castings, during transit to quench, constitute a bad heat treat and the parts have to be reheat treated.  Proper precautions are taken to avoid any excessive breezes in and around the furnace and quench tank area that would contribute to the cooling of the parts during the furnace to quench tank transit.

Metallurgical Acceptance. Metallurgical acceptance is determined in accordance with the American Society for Testing of Metals Atlas of Microstructures of Industrial Alloys according to agreed upon acceptable microstructures. A section of the part is cut and treated with an etchant used to prepare the specimens. The process includes using 2½% Nital with a Methanol rinse, followed by a second etch of 15% HCL with a Methanol rinse.

ASTM A128 Acceptable Microstructure 500x Magnification
die-casting

Sinotech can ensure excellent ASTM A128 investment castings from our Pacific Rim factories and is very price competitive. Sinotech is dedicated to managing your casting project and delivering parts to you at lower prices but with the same quality, service and terms as a domestic supplier. Click on the “Get in Touch” icon at the top of this page to get started.

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