Differences between the methods
Induction heating generates heat electromagnetically within the part; flame heating transfers heat from a gas flame to its surface. Suitable cooling follows local heating to develop the required hardened layer.
Hardened depth depends not only on frequency or flame temperature, but also on material, heating power and time, travel speed, equipment and cooling. The same process name can cover different configurations and control capabilities.
Select quenchant and spray conditions separately
Correct heating does not guarantee a uniform hardened layer. Record spray coverage and direction, nozzle condition, fluid temperature and concentration, and relative workpiece motion during process review.
Insufficient local cooling can create soft spots; differences between locations also affect results. Fluid adjustment does not replace checks of heating uniformity and spray shielding.
Verify the required result
Define hardness, hardened depth, microstructure, crack and dimensional checks from the drawing and process requirements. Depth requires a hardness profile or specified method; a single surface HRC value is not a substitute.
GB/T 5617-2025 covers determination of surface-hardened depth in steel parts and took effect on 1 March 2026. Use the method and edition required by the project.
Discuss Anran products
Start with AR-GP for conventional water-based requirements. If cooling is insufficient, discuss AR-UHS suitability. Use in a specific induction or flame-hardening spray system requires confirmation against product and site conditions, not an assumption from this article’s title.
SYQ-2 compares working-fluid performance. If actual workpiece cooling needs investigation, agree a practical temperature measurement arrangement.
AR-HCCI for high-chromium cast iron and AR-SAG for large Cr–Mo steel liners retain their specialised applications; this surface-hardening discussion does not change their positioning.
What to tell us before a quote
Tell us the material, area to harden, heating method and observed insufficient hardness or uneven cooling. Add equipment details if available; complete documentation is not required to begin.