PURPOSE: To manufacture the titled parts without carrying out isothermal transformation by heat-treating an alloy cast iron material having the composition of acicular cast iron to convert the matrix structure into granular pearlite, mechanically working the material, and heat-treating it again to convert the granular pealite into uniform bainite.

CONSTITUTION: A material consiting of, by weight, 0.5W2.0% Cu, 1.0W2.0% Mo, 1.0W3.0% Ni and the balance cast iron is heated, held at 800W1,000°C for 0.5W 6.0hr, and allowed to cool in the air. It is heated again, held at 670W760°C for 0.5W6.0hr, and allowed to cool in the air or furnace-cooled. The material heat- treated as mentioned above so as to condition the structure is mechanically worked to the shape of a product. The worked material is heated to 800W 1,000°C to austenitize the matrix structure, and it is allowed to cool in the air to convert the austenite into bainite. Thus, a cast iron product with both high workability (toughness) and wear resistance is manufactured.