Cobalt-chromium-molybdenum alloy medical material

Cobalt and chromium are two basic elements of cobalt-based alloys, and adding molybdenum can result in finer grains and higher strength after casting or forging.

CLASSIFICATION：

Medical materials

Product Category

Dental materials

KEY WORD：

Inquiry

Product Details

Cobalt and chromium are two basic elements of cobalt-based alloys, while the addition of molybdenum results in finer grains and higher strength after casting or forging. Cobalt-chromium-molybdenum alloys are basically divided into two categories: CoCrMo alloys and CoNiCrMo alloys;

1. The first category is CoCrMo alloys, which are usually cast products. In recent years, the Beijing Iron and Steel Research Institute, Beijing Rongpin Technology Co., Ltd., and Beijing Rongdian Metal Co., Ltd. have developed and produced deformable cobalt-chromium-molybdenum alloy products. Process improvements have significantly improved the comprehensive mechanical properties of this material;

2. The other category is CoNiCrMo alloys, which are usually (heat) forged and precision-machined. Cast CoCrMo alloys have been used in dentistry for decades and are currently used to manufacture artificial joints, while forged CoNiCrMo alloys are used to manufacture joints that bear heavy loads, such as knee and hip joints.

Uses

CoNiCrMo alloy is one of the promising forged cobalt-based alloys, originally known as MP35N. When stressed, it exhibits high corrosion resistance in seawater (containing chloride ions). Cold working can increase the strength of this alloy, but cold working is quite difficult, especially for manufacturing large devices such as hip stems. Hot forging is more suitable.

The wear resistance of forged CoNiCrMo alloy is similar to that of cast CoCrMo alloy. It has the advantages of good fatigue resistance and high tensile strength, making it suitable for applications requiring long life and resistance to fracture or stress fatigue, such as artificial joints in the hip joint. This advantage is important for the difficult and expensive surgery of implanting the implant deep into the femoral medullary canal.

The elastic modulus of cobalt-based alloys does not change with the change of maximum tensile strength, and its value is in the range of 220 to 234 GPa, which is higher than other materials such as stainless steel.

CoCrMo alloys are particularly susceptible to work hardening, so they cannot use the same manufacturing processes as other metals and require vacuum precision casting. Controlling the mold temperature can control the grain size of the casting. Forming coarse grains at higher temperatures will reduce the strength, but it will also precipitate larger carbides at a greater distance, reducing the brittleness of the material.

Currently, the main domestic units producing and researching and promoting cobalt-chromium-molybdenum alloys include the Iron and Steel Research Institute and Beijing Rongdian Metal Co., Ltd.