What is Special Treatment？
In order to get appropriate property of components, WHM uses various methods including special heat treatment, special polishing, coating, zinc plated etc.
Metallographic diagram of
cast ductile iron
Tensile curve of metal material
Material Selection
As an OEM manufacturer, WHM chooses the materials available in Chinese markets based on the product requirements. The material engineers in WHM are familiar with various international material standards. Through careful comparison with Chinese standards, we find the difference and try to meet customers’ requirements via substitution or special treatment. The attached table is a partial comparison of various materials heat treatment as a reference.
Heat treatment
Heat treatment methods are widely used in metal products manufacturing. Through proper heat treatment, the metal mechanical properties, such as strength, hardness, ductility, toughness, and resistance to wear, can be improved. These properties also determine the service performance of the machine components like gears, sprockets, shafts.
Material: ductile cast iron ISO 1083 SG 550-5 HRC 45 of Gear surface
The whole process: Casting—Gear surface Induction hardening--Machining
Spindle and seat for pressure relief valve made from forgings machined
Material: precipitation hardening stainless steel (17-4PH) ASTM A564 type 630
Heat treatment condition: Solution plus Age hardening H900: HRC≥40
Valve stem 17-4PH H900
Valve Spindle 630 PH H900
Valve seat 17-4PH H900
Special polishing
Material: stainless steel ANSI 304 / 316 ASTM A479 Solution heat treatment+ Special polishing
After polishing, the surface roughness of thermowell and the hole of flow conditioner can reach to Ra ≤ 8µin (0.2µm).
Painting
Orifice fitting and Valve body
Material: WCC & WCB & LCC Carbon steel
Casting—Normalization—Tempering/Quenching—Tempering—machining—Painting
Zinc Plated
Material: Carbon steel and alloy steel
Safety Valve Cap Zinc Plated
