Marquench Hardening

ThermTech is proud to offer marquench hardening for tool and die parts. This process is usually used for parts that are prone to excessive distortion or cracking and made from a salt hardenable grade of steel.  Instead of lower temperature oil or polymer, components are quenched in molten salt, which greatly reduces the risk of distortion and cracking while still providing an equivalent microstructure on many parts.

Capability & Process

ThermTech primarily utilizes two methods when it comes to marquench hardening operations for tool and die parts.  

The first is an atmosphere furnace-to-salt operation in which parts are heated (austenitized) in a batch atmosphere furnace with internal temperatures ranging from 1500-1600°F, then automatically transferred to the molten salt quench and run at a temperatures anywhere between 375°F and 500°F depending on the steel grade. Parts are then tempered down to the specified hardness range. The maximum capacity for this operation is 36”W x 72”L x 48”H with maximum weight of 7000lbs.

The second marquench hardening method we employ is a salt-to-salt process in which parts are austenitized in a high-heat salt bath, then transferred into another bath run at lower temperature for the quench. This process can be especially beneficial for products with distortion issues since it’ll spend less time at the higher temperature. The maximum dimensions the equipment used in this process allow for are 20”OD x 30”H.  

We also have an automated salt line with a working envelope of 12” W x 24” L x 30” H that can be used for this salt to salt process.

We can run both high volume parts and low volume parts by either method.  


ThermTech offers the marquench hardening processes for many alloy grades including:

  • Marquench Hardening O-1 Steel
  • Marquench Hardening 52100
  • Marquench Hardening 1075 & 1095
  • Marquench Hardening 6150
  • Marquench hardening 4140

Please note that once the tool and die materials reach a certain thickness, equivalent core properties to oil or polymer quenching may no longer be achievable with marquench hardening as the thermal driving force to provide adequate quench rates in the core of thicker parts is reduced during the high heat salt quench used in marquenching.  

The marquench process tends to be used most commonly for thin-walled materials or those made from high carbon and/or high alloy grades that are prone to cracking in any liquid quenchant process. If the parts in question have heavier sections that require core properties, oil or polymer quenching may be required to meet the specification. Please contact a technical representative at ThermTech and they will work to develop a process that will meet all part requirements with minimum distortion.

For components that are extremely prone to distortion or cracking, an austempering process may be the best option. In addition to further reducing risk of distortion and cracking, this process is also ideal for producing superior ductility properties in parts of all geometries.

Contact a sales representative today to discuss the benefits of marquench hardening for your tool and die products!