Surfacing Process for Cold Press Die Making and Repair

Literature Overview

This paper by Jiang Yucheng from Yantai Automobile Factory, published in Welding (1989, No. 9, pp. 28–29), presents a practical approach to manufacturing and repairing cold press dies using surfacing technology. The study demonstrates that surfacing can replace the use of expensive alloy tool steels for entire die components, offering significant cost savings without compromising performance. This work, though published over three decades ago, remains highly relevant in the context of sustainable manufacturing and cost-effective tool and die production.

Core Technical Content

Rationale for Surfacing in Die Manufacturing

Cold press dies are subjected to severe contact stress, abrasion, and impact during the cold-forming of sheet metal. Traditional practice requires the entire die to be made from high-grade alloy tool steel (e.g., Cr12MoV, D2, or H13), which is expensive, difficult to machine, and time-consuming to heat treat. The author proposes a composite approach:

Base material: low-carbon or low-alloy structural steel (e.g., Q235, 45 steel, or 40Cr)
Surfacing layer: high-hardness alloy deposited via arc surfacing

This approach reduces material cost by 60–80% and shortens manufacturing lead time by eliminating the need for full-depth alloy steel heat treatment.

Surfacing Process Parameters

Parameter	Value	Notes
Surfacing electrode	D407 or D408 (HRC 58–64)	Hardfacing type
Welding process	SMAW (shielded metal arc welding)	Manual arc
Current	80–120 A	Depends on electrode diameter
Polarity	DCEN	Deep penetration
Preheat	200–300 °C	To reduce cracking risk
Interpass temperature	≤ 300 °C	Controlled by pyrometer
Post-weld treatment	Tempering at 200–300 °C	To relieve residual stress
Number of passes	2–4	Depending on required thickness

Metallurgical Considerations

The key metallurgical challenge in hardfacing cold press dies is managing the crack susceptibility of high-carbon, high-alloy martensitic surfacing deposits. The following measures are critical:

Preheating: Preheating to 200–300 °C reduces the cooling rate of the weld metal, limiting the formation of brittle martensite and reducing thermal stress.
Interpass temperature control: Maintaining interpass temperatures below 300 °C prevents excessive softening of previously deposited layers while still limiting thermal gradients.
Tempering: Post-weld tempering at 200–300 °C converts retained austenite to tempered martensite, improves toughness, and relieves residual stresses.
Dilution control: The transition zone between the surfacing layer and the base material must be monitored. Excessive dilution reduces the hardness of the surfacing layer, while insufficient dilution increases cracking susceptibility.

Defect Analysis and Countermeasures

Defect Type	Root Cause	Countermeasure
Cracking (hot)	High S and P content, rapid cooling	Use low-S low-P electrodes; preheat
Cracking (cold)	High residual stress, hydrogen embrittlement	Post-weld tempering; control preheat
Porosity	Surface contamination, improper gas shielding	Clean base metal; ensure proper electrode coating
Low hardness	Excessive dilution, improper tempering	Increase passes; verify dilution ratio
Spalling	Poor bonding, thermal fatigue	Optimize surfacing thickness; control cooling rate

Engineering Practice and Economic Analysis

The author reports that surfacing-based die manufacturing achieved the following benefits:

Cost reduction: Material costs reduced by 60–70% compared to full alloy tool steel dies.
Manufacturing time: Lead time reduced by 30–50% due to elimination of full-depth heat treatment.
Performance equivalence: Surfaced dies demonstrated equivalent service life to solid alloy steel dies in cold pressing operations.
Repair economy: Surfacing repair of worn or chipped dies is far more economical than replacing the entire die component.

The economic analysis highlights that the investment in surfacing equipment and consumables is recovered within a few die manufacturing cycles, making it a highly attractive option for high-volume die production.

Study Insights and Implications

This paper provides a clear demonstration of how surfacing technology can transform die manufacturing economics. The principles described—composite construction, controlled dilution, and appropriate post-weld treatment—are foundational to modern tool and die engineering. For contemporary practice, the following extensions are relevant:

Laser cladding: Modern laser cladding processes offer even better dilution control (typically < 5%) and finer microstructure, making them ideal for precision die surfacing.
Multi-layer surfacing: Advanced multi-layer schemes with graded compositions can further improve bonding strength and thermal fatigue resistance.
Process automation: Robotic surfacing systems can ensure consistent bead quality and reduce operator-dependent variability.

The enduring value of this paper lies in its demonstration that surfacing is not merely a repair technique but a viable manufacturing strategy for producing high-performance tool components at reduced cost. Engineers involved in die manufacturing should consider surfacing as a primary design option, not merely a fallback for repair.