November 2020 Volume 2

FORGING RESEARCH AND TECHNOLOGY

Problem: Oxidation and resultant scaling leads to pit-marks and rejections. Non-value adding operations like shot blasting, grinding, etc. are costly and time consuming. Obs rvatio : Oxi at on and scaling are a function of time, temperature, and the thermodyn mic affinity between oxygen and metal. Rec nt developm nts in highly oxidation-prone grades like nickel-bearing steels, high-speed steels, and stringent customer demands do not allow for scale pits, uncontrolled decarburisation, and bad surface finish.

Subject 3: Reducing rejections and increasing yield using anti-scale protective coatings. Problem: Oxidation and resultant scaling leads to pit-marks and rejections. Non-value adding operations like shot blasting, grinding, etc. are costly and time consuming.

Observation: Oxidation and scaling are a function of time, temperature, and the thermodynamic affinity between oxygen and metal. Recent developments in highly oxidation-prone grades like nickel-bearing steels, high-speed steels, and stringent customer demands do not allow for scale pits, uncontrolled decarburisation, and bad surface finish.

Excessive scaling on billets (above) cause pit marks and rejection on forgings, as shown in adjacent image.

Technology: Anti-scale protective coating is applied on billets or components to be heated before charging them into furnace. This anti-scale coating acts as a barrier between oxygen and metal. Care is taken to apply a uniform, impervious layer of coating by brushing, spraying, or dipping.

Technology: Anti-scale protective coating is applied on billets or components to be heated before charging them into furnace. This anti-scale coating acts as a barrier between oxygen and metal. Care is taken to apply a uniform, impervious layer of coating by brushing, spraying, or dipping.

Use of anti-scale protective coatings on billets during heating for forging and again on forgings during heat treatment have proven to substantially reduce scaling, control decarburisation, improve surface finish, and increase yield. Photos below show substantially reduced scaling on billets. As a result, forged parts do not have scale pits and have acceptable surface finish.

Use of anti-scale protective coatings on billets during he ting for forging and agai on forgings during heat treatment have proven to substantially reduce scaling, control decarburisation, improve surface finish, and increase yield. Photos below show substantially reduced scaling on billets. As a result, forged parts do not have scale-pits and have acceptable surface finish.

• Shot blasting/acid pickling time is either reduced to a great extent or eliminated. • Consistently controlled decarburisation. • Increased yield.

Observation after implementing anti-scale protective coatings: Benefits proven by the use of anti-scale protective coatings are: • Substantially reduced scaling and reduced rejections due to scale pits.

Observation after implementing anti-scale protective coatings: Benefits proven by the use of anti-scale protective coatings are: • Substantially reduced scaling and reduced rejections due to scale pits. • Shot blasting/acid pickling time is either reduced to a great extent or eliminated. • Consistently controlled decarburisation. • Increased yield. SUMMARY

FIA MAGAZINE | NOVEMBER 2020 108

Forge shops are assured of increased productivity and substantially reduced costs in hot forging and heat treatment processes by the use of protective coatings like: