Abstract: In an example implementation, a sintering system includes a detection gas line to enable gas to flow into a sintering furnace from an external gas supply. The system includes a detection gas port inside the furnace through which gas from the detection gas line is to flow into the furnace, and a registration feature inside the furnace to enable positioning of a token green object proximate the gas detection port. The system includes a gas flow monitor to detect changes in gas flow through the detection gas line when the token green object shrinks during a sintering process in the furnace.

Abstract: In an example implementation, a method of operating a sintering furnace includes receiving information about a green object load to be sintered in a sintering furnace, determining a sintering profile based on the information, and performing a sintering process according to the sintering profile. During the sintering process, a sensor reading that indicates a degree of densification of a green object in the load is accessed from a densification sensor. The method includes initiating a cool down phase of the sintering process if the sensor reading has reached a target sensor reading.

Abstract: A three-dimensional printing kit can include a binding agent and a particulate build material. The binding agent can include a binder in a liquid vehicle. The particulate build material can include from about 80 wt % to 100 wt % gas-atomized stainless steel particles. The gas-atomized stainless steel particles can include from about 3 wt % to about 15 wt % nickel and from about 10 wt % to about 20 wt % chromium and can have an average oxygen content of from about 1200 ppm to about 2200 ppm by weight.

Abstract: Three-dimensional printing can include iteratively applying build material layers including stainless steel particles, iteratively applying a binding agent to individual build material layers to define individually patterned object layers that become adhered to one another to form a layered green body object, and sintering the layered green body object in a sintering oven. The stainless steel particles can include from about (2) wt % to about (6) wt % nickel, from about (14) wt % to about (19) wt % chromium, from about (2) wt % to about (6) wt % copper, and up to about (700) ppm carbon. Sintering can include ramping up the temperature to about (1240)° C. to about (1320)° C., pausing for about (30) minutes to about (12) hours, and ramping up the temperature to about (1350)° C. to about (1400)° C. for (10) minutes to about (6) hours.

Abstract: A three-dimensional printing kit can include a binding agent including a binder in a liquid vehicle and a particulate build material including from about 80 wt % to 100 wt % stainless steel particles having a D50 particle size from about 5 ?m to about 125 ?m. From about 75 wt % to 100 wt % of the stainless steel particles can be austenitic stainless steel particles including from about 10 wt % to about 12.3 wt % nickel, from about 10 wt % to about 20 wt % chromium, from about 1.5 wt % to about 4 wt % molybdenum, and up to about 0.08 wt % carbon. The austenitic stainless steel particles can have an equivalent nickel content from about 10 wt % to about 15.5 wt %.

Abstract: A three-dimensional printing kit can include a binding agent and a particulate build material. The binding agent can include a binder in an aqueous liquid vehicle. The particulate build material can include from about 80 wt % to 100 wt % metal particles that can have a D50 particle size from about 5 ?m to about 200 ?m. Individual metal particles can include an iron-containing core and can have an oxidation barrier formed thereon. The iron-containing core can include from about 90 wt % to 100 wt % iron. The oxidation barrier can have a stable average thickness from about 0.5% to about 10% of a D50 particle size of the metal particles.

Abstract: In an example implementation, a sintering system includes a detection gas line to enable gas to flow into a sintering furnace from an external gas supply. The system includes a detection gas port inside the furnace through which gas from the detection gas line is to flow into the furnace, and a registration feature inside the furnace to enable positioning of a token green object proximate the gas detection port. The system includes a gas flow monitor to detect changes in gas flow through the detection gas line when the token green object shrinks during a sintering process in the furnace.

Abstract: In an example implementation, a method of determining a sintering process endpoint includes monitoring gas flow through a detection gas line routed into a sintering furnace and through a furnace shelf on which a token green object is positioned. The method includes detecting a change in the gas flow when the token green object shrinks during a sintering process in the furnace, and determining that green objects being sintered in the furnace have reached a sintering endpoint when the change in the gas flow reaches a predetermined target.

Abstract: In an example implementation, a method of operating a sintering furnace includes receiving information about a green object load to be sintered in a sintering furnace, determining a sintering profile based on the information, and performing a sintering process according to the sintering profile. During the sintering process, a sensor reading that indicates a degree of densification of a green object in the load is accessed from a densification sensor. The method includes initiating a cool down phase of the sintering process if the sensor reading has reached a target sensor reading.